Oxford Handbook of Paediatrics (2 edn)
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Polyuria and frequency 350
Abdominal/renal mass 351
Haematuria 352
Proteinuria 354
Urinary tract infection 356
Vesicoureteric reflux 360
Acute kidney injury 362
Acute kidney injury: diagnosis and treatment 364
Chronic kidney disease 366
Chronic kidney disease: treatment 368
Congenital urinary tract anomalies 370
Inherited renal disease 372
Glomerulonephritis 374
Haemolytic–uraemic syndrome 376
Nephrotic syndrome 378
Nephrotic syndrome: complications and follow-up 380
Renal tubular disorders 382
Proximal renal tubular acidosis 384
Bartter’s syndrome 386
Renal calculi 388
Hypertension: definition 390
Hypertension: causes and features 394
Hypertension: management 396
Polyuria and frequency
This is often subjective and difficult to assess, particularly in small children. Frequency can be considered to be the inappropriate and frequent passage of small amounts of urine. Polyuria can be quantitatively defined as the passage of greater than 2000mL/1.73m2 per 24hr period.
Assessment of polyuria and frequency requires a detailed history of urinary frequency habit.
Causes of polyuria
Metabolic/endocrine disorders:
Excess and inappropriate water intake: psychogenic polydipsia (see 
p.450).
Causes of urinary frequency
Urinary tract infection (see p.356).
Bladder irritability and instability.
All causes of polyuria.
Small bladder capacity.
Investigations
Baseline screening investigations should include the following.
Urine
Urinalysis by urine dipstick testing.
Urine culture.
Urine osmolality.
Blood
Urea and electrolytes.
Plasma osmolality.
Blood glucose (random or fasting).
Abdominal/renal mass
A rare presentation of urinary tract problems, which needs to be differentiated from other causes of abdominal mass and swelling.
Causes
Intrarenal
Wilms’ tumour (young child with rapidly growing mass). See p.668.
Renal venous thrombosis (newborn with haematuria).
Benign nephroma (rare neonatal problem).
Horseshoe kidney.
Pyelonephritis (renal abscess).
Other renal
Hydronephrosis associated with the following.
Pelviureteric junction (PUJ) obstruction.
Vescioureteric junction (VUJ) obstruction.
Large bladder and bladder outlet obstruction: e.g.
posterior urethral valves (PUV);
prune belly syndrome;
neurogenic bladder.
Urinoma: i.e. an encapsulated extrapelvicalyceal collection of urine that forms from urine leakage through a tear in the collecting system or the proximal ureter.
Single cyst (benign renal cyst).
Multicystic dysplastic kidney—usually newborn.
Polycystic disease:
autosomal recessive;
autosomal dominant—rare in children.
Haematoma (trauma).
Extrarenal
Adrenal mass (e.g. neuroblastoma). See p.666.
Investigation
US will distinguish between most of the above.
Further investigation, depending on likely causes and discussion with radiology and urology colleagues, e.g. CT, MRI.
Haematuria
Blood in the urine (haematuria) may be visible to the naked eye or it may be microscopic and detected only by dipstick testing or by microscopy. The presence on microscopy of 10 or more RBCs per high-power field is abnormal. Urinary dipsticks are very sensitive and can be positive at <5 RBCs per high-power field. Asymptomatic haematuria is found in about 0.5–2% of children.
Presentation
Episode of macroscopic haematuria (causes alarm to child/family).
Incidental finding of microscopic haematuria.
Family screening and routine urinalysis.
Other causes of ‘red urine’
The following can usually be distinguished from haematuria by taking a careful history, and with urine dipstick testing and microscopy:
Haemoglobinuria/myoglobinuria.
Foods—colouring (e.g. beetroot).
Drugs (e.g. rifampicin).
Urate crystals (in young infants, usually ‘pink’ nappies).
External source (e.g. menstrual blood losses).
Fictitious—consider if no cause found.
Causes of haematuria
Urinary tract infections:
bacterial;
viral (e.g. adenovirus in outbreaks);
schistosomiasis (history of foreign travel);
tuberculosis.
Glomerular:
post-infectious glomerulonephritis;
Henoch–Schönlein purpura IgA nephropathy, SLE;
hereditary—thin basement membrane, Alport’s syndrome.
Urinary tract stones: e.g. due to hypercalciuria.
Trauma.
Other renal tract pathology:
renal tract tumour;
polycystic kidney disease.
Vascular:
renal vein thrombosis;
arteritis.
Haematological: coagulopathy/sickle cell disease.
Drugs: cyclophosphamide.
Exercise-induced.
History
UTI: fever/frequency/dysuria.
Renal stones: colicky abdominal pain.
Glomerular: sore throat/rashes.
Coagulopathy: easy bruising.
Trauma.
Family history: haematuria, deafness (Alport’s), sickle cell disease.
Examination
BP.
Abdomen: palpable masses.
Skin: rashes.
Joints: pain/swelling.
Investigations
It is important to identify serious, treatable, and progressive conditions. During an acute illness, exclude UTI by urine culture. Asymptomatic or ‘benign haematuria’ in children without growth failure, hypertension, oedema, proteinuria, urinary casts, or renal impairment is a frequent finding. Many such children require no immediate investigation but need to be checked in the outpatient clinic to see if the problem persists.
Urine:
microscopy (look for casts—suggestive of nephritis) and culture;
protein:creatinine ratio (normal, <20mg/mmol);
calcium:creatinine ratio (normal, <0.7mmol/mmol).
Bloods:
U&E/creatinine/albumin;
FBC/clotting;
complement—C3/C4, ASOT titres;
ANA/anti-dsDNA.
US urinary tract.
Urinalysis of parents (hereditary causes).
Cystoscopy: rarely indicated in children.
Treatment
If obvious cause (e.g. UTI), treat.
If complex diagnosis (impaired renal function, proteinuria, or family
history) refer to paediatric nephrology unit.
If no cause found and normal renal function, BP, and no proteinuria,
monitor until resolves.
If no resolution after 6mths or change in any of above parameters
refer to paediatric nephrology unit.
Proteinuria
This is defined as excessive urinary protein excretion. Protein may be found in the urine of healthy children, and does not exceed 0.15g/24hr.
Detection of proteinuria
Urinalysis
Performed by dipstick testing (Table 11.1), this is a cheap, practicable, sensitive method that primarily detects albumin in the urine. It is less sensitive for other forms of proteinuria.
| Test result | Equivalent protein estimate (g/L) |
|---|---|
+ | 0.2 |
++ | 1.0 |
+++ | 3.0 |
++++ | ≥20 |
| Test result | Equivalent protein estimate (g/L) |
|---|---|
+ | 0.2 |
++ | 1.0 |
+++ | 3.0 |
++++ | ≥20 |
Urinary protein:creatinine ratio (UP:UCr)
Collection of an early morning urine (EMU) specimen for measurement of the urinary protein to creatinine ratio. Normal <20mg/mmol
24hr urinary protein excretion
This is the gold standard test and requires a 24hr collection of urine to estimate urinary protein excretion.
Normal: <30mg/24hr.
Microalbuminuria: 30–300mg/24hr.
Proteinuria: >300mg/24hr.
Causes
Proteinuria may be due to benign or pathological causes.
Non-pathological proteinuria
Transient.
Fever.
Exercise.
Urinary tract infection (UTI).
Orthostatic proteinuria (postural proteinuria). This is a common cause of referral in older children. There is usually no history of significance and a normal examination. Investigations reveal a normal UP:UCr ratio in early morning urine with elevated level in afternoon specimen (may require two 12hr collections). This is regarded as a benign finding and requires no treatment.
Pathological (persistent) proteinuria
This may be seen in a number of renal disorders including:
Investigations
Proteinuria detected on dipstick testing should be confirmed using EMU UP:Ucr ratio. If the proteinuria is combined with haematuria, investigations should be directed at causes of haematuria and nephritis.
A renal US scan should also be performed.
Patients with persistent proteinuria detected over a period of 6–12mths should be referred to a paediatric nephrology centre for consideration for biopsy.
Urinary tract infection
Up to 3% of girls and 1% of boys suffer from UTI during childhood. A UTI may be defined in terms of the presence of symptoms (dysuria, frequency, loin pain) plus the detection of a significant culture of organisms in the urine:
Any growth on culture of suprapubic aspirate.
>105 Organisms/mL in pure growth from a carefully collected urine sample (midstream urine, clean catch urine, or bag urine). Ideally 2 consecutive growths of the same organism with identical sensitivities, but this is not always practical.
Note: Bacteriuria in the absence of symptoms does not necessarily need treatment, but needs to be considered in the clinical context (e.g. previous UTI, predisposing urinary tract abnormalities).
Guidance on the investigation, treatment and management of UTIs have been published.1
Clinical features
Presentation varies; symptoms in infants may be non-specific:
vomiting/diarrhoea;
poor feeding/failure to thrive;
prolonged neonatal jaundice.
Examination
Height and weight: plot on growth chart.
BP.
Examination for abdominal masses.
Examine genitalia and spine for congenital abnormalities.
Examine lower limbs for evidence of neuropathic bladder.
Diagnosis
Try to distinguish between upper (fever, vomiting, loin pain) vs. lower urinary tract symptoms (dysuria, frequency, mild abdominal pain, enuresis). Differentiation is often not possible in the younger child.
UTI is a major cause of sepsis in a young infant.
Ask about urinary stream in boys and family history of vesicoureteric reflux (VUR) or other urinary tract abnormality.
Dipstick test in the urine. ‘Leucocytes’ and ‘nitrites’ strongly suggests UTI. Urine should be sent for microscopy, culture, and sensitivity.
Acute treatment
Antibiotics should be started after urine collection (see Table 11.2).
| If child is younger than 3mths of age | Treat with parenteral antibiotics |
|---|---|
If child 3mths or older with acute pyelonephritis/upper UTI | Treat with oral antibiotics for 7–10 days or IV antibiotics for 2–4 days followed by oral antibiotics for a total duration of 10 days |
If child 3mths or older with cystitis/lower UTI | Treat with oral antibiotics for 3 days. If the child is still unwell after 24–48hr, reassess |
| If child is younger than 3mths of age | Treat with parenteral antibiotics |
|---|---|
If child 3mths or older with acute pyelonephritis/upper UTI | Treat with oral antibiotics for 7–10 days or IV antibiotics for 2–4 days followed by oral antibiotics for a total duration of 10 days |
If child 3mths or older with cystitis/lower UTI | Treat with oral antibiotics for 3 days. If the child is still unwell after 24–48hr, reassess |
Chose antibiotic from:
Trimethoprim 4mg/kg twice daily.
Cefradine 25mg/kg twice daily.
Cefalexin 25mg/kg twice daily.
Co-amoxiclav 125/31 (1–6yrs), 5mL 3 times a day.
Co-amoxiclav 250/62 (7–12yrs) 5mL 3 times a day.
IV cefuroxime 25mg/kg 8-hourly; or
IV gentamicin 2.5mg/kg/dose 8-hourly.
A repeat urine culture should be obtained on completion of antibiotics.
Follow-up and investigations
All children presenting with UTI should be investigated for any renal scarring and predisposing urinary tract abnormalities. Pyelonephritis or recurrent pyrexial UTIs need more comprehensive investigation than those at low risk (single, uncomplicated UTI with lower tract symptoms). Oral antibiotic prophylaxis (see p.358) may need to be started and continued until investigations are complete.
Recommended imaging tests (Tables 11.3–11.5)
| Test | Responds well to treatment with 48hr | Atypical UTI or recurrent UTI |
|---|---|---|
US during the acute infection | NO | YES |
US within 6wks | YES | NO |
DMSA 4–6mths after acute infection | NO | YES |
Micturating cystourethrography (MCUG) | NO | YES |
| Test | Responds well to treatment with 48hr | Atypical UTI or recurrent UTI |
|---|---|---|
US during the acute infection | NO | YES |
US within 6wks | YES | NO |
DMSA 4–6mths after acute infection | NO | YES |
Micturating cystourethrography (MCUG) | NO | YES |
| Test | Responds well to treatment with 48hr | Atypical UTI | Recurrent UTI |
|---|---|---|---|
US during the acute infection | NO | YES | NO |
US within 6wks | NO | NO | YES |
DMSA 4–6mths after acute infection | NO | YES | YES |
MCUG | NO | NO | YES |
| Test | Responds well to treatment with 48hr | Atypical UTI | Recurrent UTI |
|---|---|---|---|
US during the acute infection | NO | YES | NO |
US within 6wks | NO | NO | YES |
DMSA 4–6mths after acute infection | NO | YES | YES |
MCUG | NO | NO | YES |
| Test | Responds well to treatment with 48hr | Atypical UTI | Recurrent UTI |
|---|---|---|---|
US during the acute infection | NO | YES | NO |
US within 6wks | NO | NO | YES |
DMSA 4–6mths after acute infection | NO | NO | YES |
MCUG | NO | NO | YES |
| Test | Responds well to treatment with 48hr | Atypical UTI | Recurrent UTI |
|---|---|---|---|
US during the acute infection | NO | YES | NO |
US within 6wks | NO | NO | YES |
DMSA 4–6mths after acute infection | NO | NO | YES |
MCUG | NO | NO | YES |
UTI prevention
Predisposing factors to recurrent UTIs should be avoided:
Treat and prevent constipation.
Hygiene: clean perineum front to back.
Avoid nylon underwear and bubble baths.
Encourage fluid intake and regular toileting with double micturition.
Do not routinely use antibiotic prophylaxis after first-time UTI, but consider it after recurrent UTI.
Oral antibiotic prophylaxis (trimethoprim 2mg/kg at night or nitrofurantoin 1mg/kg) is required if:
VUR.
Recurrent UTIs (more than 2–3 episodes).
Reference
www.nice.org.uk/nicemedia/pdf/CG54fullguideline.pdf
Vesicoureteric reflux
This is the retrograde flow of urine from the bladder into the upper urinary tract. VUR is usually congenital in origin, but may be acquired (e.g. post-surgery). VUR combined with UTI leads to progressive renal scarring. Such reflux nephropathy may progress to end-stage renal failure if untreated. Incidence of VUR is ˜1% in newborn infants. It is observed in 30–45% of young children (<5yrs) presenting with UTI. There is often a strong family history with a 35% incidence rate among siblings of affected children. So called ‘congenital reflux’ is also now recognized as result of routine antenatal scanning. This can result in small, smooth underdeveloped kidneys in otherwise asymptomatic children.
Grade of VUR
The extent of retrograde reflux from the bladder can be graded according to the International Reflux Study grading system:
I: into ureter only.
II: into ureter, pelvis, and calyces with no dilatation.
III: with mild/moderate dilatation, slight or no blunting of fornices.
IV: with moderate dilatation of ureter and/or renal pelvis and/or tortuosity of ureter, obliteration of sharp angle of fornices.
V: gross dilatation, tortuosity, no papillary impression visible in calyces.
Diagnosis
The diagnosis of VUR is established by radiological techniques.
Micturating cystourethrogram
This technique involves urinary catheterization and the administration of radiocontrast medium into the bladder. Reflux is detected on voiding.
Advantages: grade of reflux seen.
Disadvantages: requires bladder catheterization, radiation dose.
Indirect cystogram
A radionucleotide method. Includes mercaptoacetyltriglycine (MAG-3) and diethylenetriamine pentaacetic acid (DTPA) scans.
Advantages: no catheterization required; lower radiation dose.
Disadvantages: false negatives found; co-operation of child to void is needed.
Follow-up and treatment
The aims are to prevent progressive renal scarring. Prophylactic antibiotics may be used to prevent this and imaging by indirect cystogram (e.g. MAG-3) and DMSA are sometimes used for follow-up. Randomized controlled trials of medical versus surgical treatment show surgery can reduce the incidence of pyelonephritis, but there is no difference in scarring compared with medical treatment.
Medical therapy
Antibiotic prophylaxis therapy (as for UTI – see previous section).
Surgery
Not routinely recommended. Indications for surgery include failed medical therapy, or poor compliance.
‘STING’ procedure (subureteric Teflon injection): commonly used.
Endoscopic injection of materials behind ureter to provide a valve mechanism during bladder filling and emptying. Longevity and need for repeat treatments not fully known.
Open surgery: re-implantation of ureters.
Prognosis
Spontaneous resolution of VUR often occurs, especially with lower grades of reflux.
Bilateral reflux (grades IV and V) and reflux into duplex systems is associated with lower probability of resolution.
Acute kidney injury
Acute kidney injury (AKI) is a sudden reduction in glomerular filtration rate resulting in an increase in blood concentration of urea and creatinine and disturbed fluid and electrolyte homeostasis (see also p.94).
Classification
The causes of AKI (Box 11.1) can be divided into pre-renal, renal, and post-renal. A patient may have more than one cause for their AKI.
Hypovolaemia, e.g. 2° to gastroenteritis, haemorrhage, DKA,
nephrotic syndrome
Peripheral vasodilatation, e.g. sepsis
Impaired cardiac output, e.g. congestive cardiac failure
Drugs, e.g. ACE inhibitors
Acute tubular necrosis (usually following pre-renal)
Interstitial nephritis (usually drug-induced)
Glomerulonephritis
Haemolytic–uraemic syndrome (HUS; see p.376)
Cortical necrosis
Bilateral pyelonephritis
Nephrotoxic drugs, e.g. aminoglycoside, IV contrast, NSAIDs
Myoglobinuria, haemoglobinuria
Tumour lysis syndrome (see p.684)
Renal artery/vein thrombosis
Obstruction
Post-urethral valves (PUV)
Neurogenic bladder
Calculi
Tumours (rhabdomyosarcoma in infancy)
History
It is important to include the following points:
History of sore throat/rash (e.g. streptococcal glomerulonephritis).
Urinary symptoms of:
haematuria, frequency, dysuria (e.g. pyelonephritis);
poor stream (e.g. PUV).
Significant antenatal history.
Drugs.
Examination
It is important to assess and document the following.
Height and weight (compare with any recent/past measurements).
Fever.
Hydration status: any evidence of oedema/dehydration?
Haemodynamic status including BP.
Presence of any rashes/arthropathy.
Abdomen: tenderness or masses.
Neurology: exclude possible neuropathic bladder.
Investigations
Urine
Urinalysis with microscopy of fresh urine, e.g. evidence of casts.
Culture, e.g. pyelonephritis.
Osmolality, Na, creatinine, fractional excretion of sodium ( p.364).
Protein:creatinine ratio to document proteinuria if dipstick +ve.
Myoglobin if evidence of rhabdomyolysis.
Urine calcium/oxalate to creatinine ratios if renal calculi suspected.
Blood investigations
Urea, electrolytes, creatinine, Ca2+, PO43−, albumin, glucose, bicarbonate.
Plasma osmolality.
FBC and film.
Blood cultures, if clinically septic.
In suspected nephritis:
complement levels;
anti-streptolysin O titre (ASOT), antiDNAaseB;
antinuclear antigen (ANA), anti-dsDNA, anti-neutrophil cytoplasmic antibodies (ANCA).
Uric acid if tumour lysis suspected.
Creatinine kinase if possible myoglobinuria.
Clotting if septic or potential need for biopsy or dialysis access.
Drug levels if relevant (e.g. gentamicin).
Escherichia coli 0157 serology.
Cultures
Stool culture: E. coli 0157 (HUS).
Throat swab.
Radiology
US(+/− Doppler): kidneys and bladder.
CXR if evidence of fluid overload.
Acute kidney injury: diagnosis and treatment
Diagnosis
The following urinary indices may be helpful providing no diuretics have been given (Table 11.6).
| Test | Pre-renal | Renal | Post-renal |
|---|---|---|---|
Urine osmolality (mosmol/kg) | >400–500 | <350 | Variable |
Urine/plasma Cr ratio | >40 | <20 | <20 |
Urine Na (mmol/L) | <20 | >40 | Variable |
FENa | <1% | >2% | Variable |
| Test | Pre-renal | Renal | Post-renal |
|---|---|---|---|
Urine osmolality (mosmol/kg) | >400–500 | <350 | Variable |
Urine/plasma Cr ratio | >40 | <20 | <20 |
Urine Na (mmol/L) | <20 | >40 | Variable |
FENa | <1% | >2% | Variable |
To accurately interpret fractional excretion of sodium (FENa), patients should not have recently received diuretics. FENa is greater than 1% (and usually greater than 3%) with acute tubular necrosis and severe obstruction of the urinary drainage.
FENa = [(UNa × PCr)/(PNa × UCr)] × 100
where UNa and UCr are urinary Na and creatinine, respectively, and PNa and PCr are plasma Na and creatinine, respectively.
Treatment
Liaise with a paediatric nephrology centre early and treat the following.
Specific treatment depends on the underlying cause. However, the following general management principles apply:
Observations: daily weight, BP, strict fluid input and output monitoring.
Fluids management: Pre-renal—fluid bolus (10mL/kg of 0.9% saline) and furosemide. Otherwise, restrict to insensible losses (400mL/m2) + urine output. Consider adding diuretic therapy.
Electrolytes: monitor at least 12-hourly until stable. K+ and PO4 restricted diet. Consider adding PO4 binder.
BP: treat hypertension (see p.396).
Medications: adjust drug doses according to level of renal impairment.
The patient may require transfer to a paediatric nephrology centre if dialysis looks likely or there is uncertainty about the diagnosis.
Indications for dialysis
The following are indications for urgent dialysis in ARF.
Severe hyperkalaemia.
Symptomatic uraemia with vomiting/encephalopathy (usually urea
>40mmol/L).
Rapidly rising urea and creatinine.
Symptomatic fluid overload, especially cardiac failure or pericardial
effusion.
Uncontrollable hypertension.
Symptomatic electrolyte problems or acidosis.
Encephalopathy or seizures.
Prolonged oliguria: conservative regimen controls ARF, but causes nutritional failure.
Removal exogenous toxins or metabolite (inborn error).
Note: Patients with haemolytic–uraemic syndrome should be referred as soon as the child becomes oliguric or if urea is raised as current practice is to dialyse early to reduce neurological complications and to allow transfusion.
Acute dialysis—methods
Peritoneal dialysis (abdominal catheter).
Haemodialysis (femoral or jugular access).
Haemofiltration (usually continuous veno-venous haemofiltration).
Chronic kidney disease
Most children with CKD are asymptomatic until approaching chronic renal disease stage 4 (see Table 11.7). CKD should be suspected if:
failure to thrive;
polyuria and polydipsia;
lethargy, lack of energy, poor school concentration;
other abnormalities such as rickets.
| Stage | Description | GFR* (mL/min/1.73m2) |
|---|---|---|
1 | Kidney damage with/without increased GFR | >90 |
2 | Kidney damage with mild decrease in GFR | 60–89 |
3 | Moderate decrease in GFR | 30–59 |
4 | evere decrease in GFR | 5–29 |
5 | Kidney failure | <15 (or dialysis) |
| Stage | Description | GFR* (mL/min/1.73m2) |
|---|---|---|
1 | Kidney damage with/without increased GFR | >90 |
2 | Kidney damage with mild decrease in GFR | 60–89 |
3 | Moderate decrease in GFR | 30–59 |
4 | evere decrease in GFR | 5–29 |
5 | Kidney failure | <15 (or dialysis) |
GFR, Glomerular filtration rate.
See Box 11.2 for summary of causes.
Renal dysplasia
Obstructive uropathies
Vesicoureteric reflux nephropathy
Hereditary (17%)
Polycystic kidney disease
Nephronophthisis
Hereditary nephritis
Cystinosis
Oxalosis
Focal segmental glomerulosclerosis
Multisystem disorders (9%)
Systemic lupus erythematosus
Henoch–Schönlein purpura
Haemolytic–uraemic syndrome
Wilms’ tumour
Renal vascular disease
Unknown
CKD: correcting common misconceptions
Plasma creatinine can remain normal until GFR reduced to <50%.
Urine flow rate may not mean a good GFR as many children with renal dysplasia have polyuria and nocturia.
Other urinary abnormalities such as proteinuria, glycosuria can be an indicator of tubular dysfunction.
The focus is on GFR and not plasma creatinine
GFR can be formally measured by the Iohexol method or alternatively by 51Cr EDTA or inulin methods clearance,
In ordinary clinical practice GFR (mL/min/1.73m2) may be estimated (note: less accurate in children <2yrs or >14yrs):
GFR (estimated) = 40 × height (cm)/creatinine (μmol/L).
Investigations
Urinalysis.
Blood:
FBC + iron studies if anaemic;
electrolytes/Ca/PO4/ALP/albumin;
pH/bicarbonate;
parathyroid hormone (PTH).
Renal tract US.
Left hand and wrist X-ray for bone age and renal osteodystrophy score.
ECG/echocardiography for signs of left ventricular hypertrophy if hypertensive.
Chronic kidney disease: treatment
There should be early liaison with and referral to a regional paediatric nephrology centre.
Urgent life-threatening abnormalities
High/low plasma K+.
Low plasma Na+/acidosis/low Ca2+/high. PO43−.
High/low BP.
Nutrition
Early involvement of the paediatric dietician is needed.
Estimated average requirement (EAR) should be worked out.
often require supplements to achieve this;
NG/gastrostomy feeds.
Minimum protein intake of EAR for age.
Vitamin supplements (but not vitamin A).
Fluid and electrolyte balance
Avoid high K+-containing foods (e.g. banana, chocolate).
Many causes of chronic renal failure (CRF) cause polyuria and Na+ wasting; therefore, Na+ supplements are needed.
If clinical fluid overload, Na+ restriction and diuretics.
Acid–base balance sodium bicarbonate supplements.
Renal osteodystrophy
Control of plasma PO4. Restrict dietary intake/PO4 binders.
Calcitriol (vitamin D) 15ng/kg/day.
Monitor PTH.
Anaemia
Assess iron status: oral iron supplements.
Subcutaneous erythropoietin.
Hypertension, see p.396.
Preservation of renal function
Control hypertension.
Reduce proteinuria: e.g. angiotensin-converting enzyme (ACE) inhibitor/angiotensin receptor blocker therapy.
‘Statin’ therapy: evidence of benefit from adult CRF trials.
Growth
Optimize nutrition, acid–base balance, electrolyte balance.
If failing height velocity (HV –2 SD or below) or short stature (Ht –2 SD or below) despite correction of above, treatment with recombinant human growth hormone is indicated.
Education and preparation for dialysis/transplantation
Information provision.
Meet team.
Meet other families.
Dialysis
Peritoneal dialysis (PD)
Preferred choice is automated peritoneal dialysis (APD) performed in
patient’s home (with mobile machines); therefore minimal disruption.
Main risks: peritonitis and catheter blockage.
Needs family and social support.
Haemodialysis (HD)
Extracorporeal circuit.
Vascular access by jugular venous catheter.
Increasingly, long-term vascular access is by AV fistula (wrist or elbow). Therefore, avoid non-dominant arm for venepuncture and IV.
Usually 4hr session, 3 times/wk in hospital.
Home HD possible if there is a family member to support this.
Renal transplantation
This is the ultimate goal in CRF.
Minimum 10kg (or when immunizations complete).
Deceased donor vs. living-related donor (LRD) source.
Pre-emptive transplantation before dialysis required is ideal.
LRD by laparoscopic donor nephrectomy is now standard.
Graft survival 85% after 2yrs.
Lifelong immunosuppression is required.
Psychosocial support
For patient and family this is crucial as CRF is lifelong treatment.
Focus on prevention of cardiovascular disease, which is a major cause
of mortality and morbidity in adult life.
Congenital urinary tract anomalies
Increasingly, urinary tract anomalies are being detected earlier by the use of routine antenatal ultrasound scans.
Renal anomalies account for about 20% of all significant abnormalities found on detailed scans at 18–20wks gestation.
Close liaison between obstetricians, paediatrician, and surgeon with regard to counselling the parents and follow-up is vital.
Centres should have a postnatal investigation protocol as the majority of infants will be asymptomatic.
Amniotic fluid volume
Oligohydramnios: low urine production or obstruction of urine excretion that may lead to pulmonary hypoplasia.
Polyhydramnios: polyuria.
Renal size
Enlarged: cystic kidneys (any cause); hydronephrosis.
Small: dysplasia.
Hydronephrosis
Unilateral: pelviureteric junction (PUJ) or vescioureteric junction (VUJ) obstruction; vescioureteric reflux (VUR).
Bilateral: bladder outlet obstruction, e.g. PUV, VUR, prune belly syndrome.
Renal cysts
Multicystic dysplastic kidneys (MCDK).
Polycystic kidney disease (PCKD).
Cystic dysplasia.
Abnormal renal parenchyma
Echogenic:
cystic kidneys (any cause);
congenital nephrotic syndrome (may have polyhydramnios, large
placenta).
Investigations
If a major problem is suspected (e.g. PUV, bilateral severe hydronephrosis, palpable kidneys), a renal US should be performed after 24hr of age. Otherwise routine postnatal investigation with U/S (at 2–4wks), MCUG (at 4–8wks), and radionuclide scan (at 8–12wks of age).
Clinical management
In the postnatal period, ensure male infants have voided and that a good urinary stream is observed. The initial postnatal US finding guides further management.
MCUG only routine if strong suspicion of VUR (e.g. dilated ureters/intermittent dilatation of pelvis). Will need cover with antibiotics (e.g. oral trimethoprim) for the procedure.
Give antibiotic prophylaxis (e.g. oral trimethoprim) to all babies with suspicion of VUR.
Radionuclide scan depends upon lesion:
DMSA if function of kidney required (e.g. MCDK, VUR);
MAG-3 renogram if ‘obstruction’ being evaluated (e.g. PUJ, VUJ).
Most infants with hydronephrosis can be conservatively managed if they are asymptomatic.
Inherited renal disease
Many renal abnormalities are inherited. Recognition of these is important, not only in terms of diagnosis and treatment of the patient, but also for screening and genetic counselling for the whole family.
New therapies may become available as gene therapy is researched.
Ethical considerations are very important in this group in terms of family screening and counselling.
Databases such as Online Mendelian Inheritance in Man (OMIN) provide comprehensive lists. Below are a few of the more common conditions.
Autosomal dominant inheritance
Polycystic kidney disease (ADPKD). Commonest inherited renal disease (1/400 to 1/1000), which usually only manifests in adult life, but cysts can be seen on US scan in children. Multi-organ involvement (intracranial aneurysms, liver and pancreatic cysts, mitral valve prolapse), abdominal mass, haematuria, pain (rare presentation in neonatal period with abdominal masses and/or high or low BP, renal impairment).
Skin: ‘ash-leaf’ macule; adenoma sebaceum; shagreen patch.
Neurological: seizures.
Cardiac: rhabdomyoma.
Renal: cysts; angiomyolipomas; high or low BP; renal impairment.
Branchio-oto-renal syndrome Hearing loss, branchial arch defects, renal anomalies.
Autosomal recessive inheritance
Polycystic kidney disease (ARPKD)
Incidence 1:20 000 to 1:40,000.
Oligohydramnios and large echogenic kidneys.
Fusiform dilatation of collecting tubules.
Prognosis depends on degree of pulmonary involvement.
This usually presents at an earlier age than ADPKD and progresses to renal failure in a shorter time.
Liver involvement leads to portal hypertension in later life
Bardet–Biedl syndrome: obesity, polydactyly, mental retardation, retinitis pigmentosa, hypogenitalism, renal anomalies commonly found ( p.949).
Cystinosis (Fanconi’s syndrome): excess storage of cystine due to defect in transport system of cystine out of cell. Accumulates in various organs (cornea, thyroid, brain, leading to growth failure)—eventual renal failure.
Nephronophthisis: polyuria, polydipsia, tubulopathy and childhood onset renal failure.
Primary hyperoxaluria: see p.389 (renal calculi).
Cystinuria: recurrent calculi.
X-linked
Alport’s syndrome: sensorineural deafness with progressive nephritis.
Nephrogenic diabetes insipidus.
Fabry’s disease: deficiency of alpha-galactosidase A; now treatable ( p.968).
Sporadic
Glomerulonephritis
A combination of haematuria, oliguria, oedema, and hypertension with variable proteinuria.
Majority of cases post-infectious.
Usually presents 1–2wks after a URTI and sore throat.
Bacterial: streptococcal commonest, Staphylococcus aureus,
Mycoplasma pneumoniae, Salmonella
Virus: herpesviruses (EBV, varicella, CMV)
Fungi: candida, aspergillus
Parasites: toxoplasma, malaria, schistosomiasis
MPGN
IgA nephropathy
Systemic lupus erythematosis
Subacute bacterial endocarditis
Shunt nephritis
Investigations
Urine:
urinalysis by dipstick: haematuria +/− proteinuria;
microscopy—casts (mostly red cell casts).
Throat swab: culture.
Bloods:
FBC;
U&E, including creatinine, bicarbonate, calcium, phosphate, and
albumin;
ASOT/antiDNAase B;
complement (expect low C3, normal C4);
autoantibody screen (include ANA).
Renal US (urgent).
CXR (if fluid overload suspected).
Management
Most require admission because of fluid balance, worsening renal function, or hypertension. Treat life-threatening complications first:
Otherwise supportive treatment.
Fluid balance:
weigh daily;
no added/restricted salt diet;
if oliguric, fluid restrict to insensible losses (400mL/m2) + urine
output;
consider furosemide 1–2mg/kg bd if fluid overloaded.
Hypertension:
treat fluid overload;
α-blockers and calcium channel blocker usual first choice;
Note: Do not use ACE inhibitor (may worsen renal function).
Infection: 10-day course of penicillin (does not affect natural history, but limits spread of nephritogenic bacterial strains).
When to refer to paediatric nephrology unit
Patients with life-threatening complications (see Management).
Those with atypical features, including:
worsening renal function;
nephrotic state;
evidence of systemic vasculitis (e.g. rash);
normal C3 complement levels;
increased C4 complement levels;
+ve ANA;
persisting proteinuria at 6wks;
persisting low C3 at 3mths.
Prognosis
95% with post-streptococcal glomerular nephritis (GN) show complete recovery.
Microscopic haematuria may persist for 1–2yrs.
Discharge from follow-up once urinalysis, BP, and creatinine are normal.
Haemolytic–uraemic syndrome
This is the commonest cause of AKI in children in Europe and the USA. It typically has a seasonal variation with peaks in the summer and autumn months. It presents with a triad of:
microangiopathic haemolytic anaemia;
thrombocytopenia;
acute renal failure.
Two forms of HUS are recognized.
Atypical/sporadic:
not diarrhoea-associated (D− HUS);
often familial.
Epidemic form:
diarrhoea-associated (D+ HUS);
commonly associated with verocytotoxic producing E. coli 0157.H7 type, although other pathogens have also been implicated (e.g. Shigella, Streptococcus pneumoniae).
E. coli are common bacteria, normally found in the gut of warm-blooded animals. There are many types of E. coli, most of which are harmless. However, the enterohaemorrhagic E. coli (EHEC) produce toxins (poisons) that can cause gastroenteritis with blood in the stool. The toxins are called shiga toxins or verotoxins; hence, EHEC is also called STEC or VTEC. VTEC is found in the gut of cattle, and can also be found in the gut of humans without causing illness. The bacteria can be passed on to humans by:
Eating improperly cooked beef, in particular, ground or mince beef.
Drinking raw (unpasteurized) milk.
Close contact with a person who has the bacteria in their faeces.
Drinking contaminated water.
Swimming or playing in contaminated water.
Contact with farm animals.
Clinical features
Acute renal failure
Gut
Prodrome of bloody diarrhoea.
Rectal prolapse.
Haemorrhagic colitis.
Bowel wall necrosis and perforation.
Pancreas (occurs in <10%)
Glucose intolerance/insulin-dependent diabetes mellitus.
Pancreatitis.
Liver jaundice.
Neurological Irritability to frank encephalopathy.
Cardiac myocarditis (rare)
Investigations
FBC + film.
Blood cultures.
U&E.
LFTs.
E. coli polymerase chain reaction (PCR).
Stools: microscopy and culture.
Treatment
Early liaison with a paediatric nephrology unit is required, as early dialysis may be needed. Management is mainly supportive and directed at treating the clinical features of HUS. Antibiotics for underlying E. coli infection are not indicated.
Monitor electrolyte balance.
Monitor fluid balance.
Nutrition.
Blood transfusion (note risks/concerns regarding fluid overload and
hyperkalaemia).
Treat hypertension.
Outcome
Generally good.
Mortality <5%.
Long-term: up to 30% may develop mild impairment of GFR.
Nephrotic syndrome
This is defined as a combination of:
Heavy proteinuria (urinary protein to creatinine ratio >200mg/mmol).
Hypoalbuminaemia (albumin <25g/L).
Oedema.
Hyperlipidaemia.
The incidence is approximately 2/100,000 children with a peak age of onset in children aged <6yrs. Boys are more commonly affected than girls (2:1) and there is an increased frequency in certain ethnic groups, e.g. Indian subcontinent. Nephrotic syndrome can be either primary or secondary
Primary
Congenital.
Infantile.
Secondary
Minimal change disease (MCD): commonest (85%).
Focal segmental glomerulosclerosis (FSGS; 10%).
Membranoproliferative glomerulonephritis (MPGN; 5%).
Membranous glomerulonephritis (MGN).
Classification
Nephrotic syndrome can be clinically classified as being either steroid-sensitive (SS), steroid dependent or steroid-resistant (SR). The majority of MCD is SS.
MCD (SS), >95%.
FSGS (SS), 20%.
MPGN (SS), 55%.
Clinical features
Most children present with insidious onset of oedema, which is initially perorbital, but becoming generalized with pitting oedema. Perorbital oedema is often most noticeable in morning on rising. Ascites and pleural effusions may subsequently develop.
Examination
This should establish the extent of dependent oedema, e.g. facial, ankle, scrotal, etc. Assessment should also include:
Height and weight (compare with previous/recent measurements).
BP.
Peripheral perfusion.
Investigations
Urine
Urinalysis: protein +++.
Microscopy: haematuria/casts (suggest causes other than MCD).
Na+: If <10mmol/L suggests hypovolaemia. (Note: If patient has received diuretics this is not accurate.)
Culture.
Protein:creatinine ratio (early morning urine specimen).
Bloods
Serum albumin (reduced, <25g/L).
U&E/creatinine (decreased sodium and total calcium—with normal ionized calcium).
C3/C4 (if decreased suggests not MCD).
Consider ANF, ASOT, ANCA, immunoglobulins if mixed nephritic/nephrotic picture.
Lipids: total cholesterol/low density lipoprotein (LDL)/very low density lipoprotein (VLDL).
Haemoglobin may be increased or decreased depending on plasma volume.
Varicella zoster immunity status.
Management
Patients should be admitted, particularly if this is their first episode or if there are concerns regarding complications. Management is initially aimed at fluid restriction and prevention of hypovolaemia. A trial of oral steroid therapy to induce remission is also started. Prophylaxis against bacterial infection (particularly pneumococcal) is also required.
Treatment
Treat hypovolaemia if present but albumin infusion is not routine.
Fluid restriction to 800–1000mL/24hr.
Diuretics if very oedematous and no evidence of hypovolaemia. Furosemide/spironolactone.
Steroid therapy:
oral prednisolone 60mg/m2/day for 4wks;
followed by 40mg/m2/alternate days for 4wks; then
stop—slow wean over next 4mths with slow taper, but need to consider side-effects of steroids.
Other measures
Diet (no added salt and healthy eating—not high protein).
Prophylactic antibiotics (oral penicillin V) until oedema-free.
Immunize with pneumococcal vaccine.
Nephrotic syndrome: complications and follow-up
Complications
Complications are 2° to the relative hypovolaemic state and to impaired immunity.
Infection
Predisposition to infection is 2° to decreased IgG levels, and to impaired opsonization due to steroid immunosuppression. Bacterial peritonitis (especially Streptococcus pneumoniae) is an important complication and should be considered in any child with nephrotic syndrome who complains of abdominal pain. Urgent assessment, cultures, and IV antibiotic therapy are required.
Thrombosis
Nephrotic syndrome produces a hypercoagulable state and predisposition to both arterial and venous thrombosis is recognized.
Hypovolaemia
Suggested by development of oliguria and or presence of low BP. Patients may also complain of abdominal pain. If present, administration of an infusion of 20% human albumin solution 1g/kg over 2hr with furosemide (2mg/kg IV) should be given.
Acute renal failure
This is pre-renal and 2° to hypovolaemia.
Indications for renal biopsy
The majority of patients will have MCD and will respond to steroids. Biopsy is therefore reserved for those with atypical features:
Age <12mths or >12yrs.
Increased BP.
Macroscopic haematuria.
Impaired renal function.
Decreased C3/C4.
Failure to respond after 1mth of daily steroid therapy.
Follow-up
Prognosis
30% single relapse.
30% occasional relapses.
30% steroid dependence.
Relapse
Many patients with steroid-sensitive nephrotic syndrome will relapse. A relapse is defined as detection of urine dipstick ++ proteinuria for >3 days.
Frequent relapse is defined as >2 relapses within 6mths of initial response or 4 or more relapses in any 12mths.
Management of relapses
Each relapse is treated with oral steroids in a similar manner to above. Alternative strategies for frequent relapsers include a trial of therapy with other agents such as:
Cyclophosphamide.
Levamisole.
Ciclosporin A.
Other agents including the immunosuppressants tacrolimus, mycophenolate mofetil and anti-CD20 monoclonal antibody (rituximab) may be considered.
Renal tubular disorders
The renal tubules are responsible for the regulation of fluid, acid–base, and electrolyte balance. Abnormalities of renal function may occur at any point along the length of the renal tubule system and may lead to a disturbance in the equilibrium of any of the substances handled by it. It is essential to consider these disorders when there are any of the following:
Glycosuria, amino-aciduria, or impaired ability to concentrate or acidify urine shown on urinalysis.
Stones or nephrocalcinosis: distal tubular acidosis and oxalosis are major causes.
Polyhydramnios and failure to thrive in a newborn: e.g. Bartter syndrome associated with hypokalaemic alkalosis.
Failure to thrive with rickets: cystinosis is commonest cause of Fanconi syndrome.
Major rickets with low plasma phosphate levels: familial hypophosphataemic rickets.
Failure to thrive with low urine osmolality: nephrogenic diabetes insipidus.
Renal tubular acidosis
Renal tubular acidosis (RTA) is a state of systemic hyperchloraemia resulting from impaired urinary acidification. Three types of RTA exist:
Proximal renal tubular acidosis
25% of urinary bicarbonate is lost.
Plasma bicarbonate level falls until it reaches a threshold when urinary bicarbonate wasting ceases (approximately 15–18mmol/L).
Urinary acidification to pH values <5.5 is not possible.
Proximal RTA may occur as an isolated disorder with no other abnormalities of tubular function. This form may be transient and is occasionally inherited. Proximal RTA also occurs as a more generalized defect of proximal tubular transport characterized by:
RTA.
Excessive urinary loss of glucose, phosphate, amino acids, sodium, potassium, calcium, and uric acid. This generalized form is known as Fanconi syndrome, which may be 1° or 2° to several inherited and acquired disease states (see Box 11.3).
Isolated: sporadic or inherited
Primary Fanconi syndrome
Secondary Fanconi syndrome, inherited:
cystinosis;
galactosaemia;
Wilson’s disease;
Lowes syndrome.
Secondary Fanconi system, acquired: vitamin D deficient rickets.
Secondary Fanconi system: hypothyroidism
Isolated: sporadic or inherited.
Secondary to nephritis:
obstructive nephropathy
pyelonephritis
Secondary to toxins: amphotericin B
Lithium
Distal RTA See also p.385. This is due to deficiency in hydrogen ion secretion by the distal renal tubules and collecting ducts. Urine pH cannot be reduced 5.8. Hyperchloraemia and hypokalaemia are characteristic, but less severe than that found in proximal RTA. Nephrocalcinosis may be present. Distal RTA may be isolated or secondary (see Box 11.3).
Clinical features of RTA Children with isolated forms of proximal and distal RTA usually present with failure to thrive in infancy. Those with the 2° forms of RTA may present in a similar way.
Diagnosis
Other causes of systemic acidosis (e.g. chronic diarrhoea, lactic acidosis, diabetic ketoacidosis) should be excluded. Investigation to establish a diagnosis of RTA should include:
Blood: pH; bicarbonate (low); potassium (low); chloride (high).
Urine—early morning sample:
pH < 5.5 suggests proximal RTA;
pH ≥ 5.8 suggests distal RTA.
If proximal RTA is detected, blood and urinalysis to establish other tubular defects should be undertaken.
Treatment
The main aims are correction of acidosis and maintenance of normal bicarbonate and potassium. This can be achieved by alkali (citrate or bicarbonate)/potassium-containing solutions.
Bartter’s syndrome
This is a relatively rare form of renal tubular dysfunction. The condition is best described as a defect in chloride reabsorption in the ascending loop of Henlé, resulting in:
excessive potassium excretion;
increased prostaglandin synthesis;
stimulation of the renin–angiotensin–aldosterone system.
Clinical features
Young children present with:
failure to thrive;
poor growth;
muscle weakness;
constipation.
Polyuria and polydipsia due to excessive salt and water loss may be evident.
Diagnosis
Characteristic findings include:
hypokalaemia;
hypochloraemia;
raised plasma renin and aldosterone levels;
normal BP.
Urine potassium and chloride levels are high.
Treatment
Goals are to maintain serum potassium levels >3.5mmol/L and to ensure adequate nutrition. Therapy includes a combination of oral potassium supplement together with a potassium-sparing diuretic (e.g. spironolactone) and indomethacin (prostaglandin inhibitor).
Renal calculi
The incidence of renal calculi varies according to geography and socio-economic conditions around the world. In the UK it affects approximately 1.5/million child population.
Aetiology
Infective
Commonest cause in children in UK.
Associated with chronic UTI with Proteus—‘staghorn’ calculi.
Also UTI with Pseudomonas, Klebsiella, E. coli.
Associated with urinary stasis
Congenital malformations, e.g.:
pelviureteric junction obstruction;
megaureter.
Metabolic
Hypercalciuria: i.e. 24hr urinary Ca >0.1mmol/kg/day or urinary
Ca:creatinine ratio >0.74mmol/mmol:
primary hyperparathyrodism;
idiopathic infantile hypercalcaemia;
hypervitaminosis D;
prolonged immobilization.
Cystinuria (autosomal recessive condition): typically radiolucent stones.
Oxalosis: primary hyperoxaluria type I (PH1).
Uric acid stones:
myeloproliferative disorders following medication/chemotherapy
for patients with leukaemia, lymphoma;
Lesch–Nyhan syndrome.
Clinical features
Most children will present with either gross or microscopic haematuria. They may be otherwise asymptomatic. The classic symptoms of renal colic are uncommon, e.g. intense pain located in the abdomen or in the loins and back. Symptoms and signs of a UTI may also be present. Some children may describe a sensation of ‘having passed gravel’ on micturition.
Investigations
Urine
Dipstick analysis.
Microscopy (pH, cells, crystals).
Culture (exclude infection).
Calcium:creatinine ratio; oxalate:creatinine ratio.
Amino acid screen.
Blood
U&E, bicarbonate, creatinine.
Calcium, phosphate, PTH.
Liver function tests.
Uric acid.
Renal tract ultrasound
Other investigations
AXR:
radio-opaque stones: calcium/cysteine/infective;
radiolucent stones: uric acid/xanthine.
IV pyleogram or CT scan.
Renal stone analysis: composition.
Treatment
The acute treatment of renal colic secondary to renal stones is based on the provision of adequate analgesia and hydration. Treat any underlying UTI with antibiotics. If severe renal impairment and urinary tract obstruction is evident refer to the paediatric urology team for consideration for extracorporeal shock-wave lithotripsy. Surgery (e.g. percutaneous nephrolithotomy or open surgery) is now seldom indicated. Long-term management is aimed at preventing further obstruction and bouts of renal colic. The simplest and most effective measures to achieve this are to ensure adequate hydration and diuresis to maintain a good urinary flow and dilute urine. Treatment of any underlying urinary tract infection and metabolic disorder is also required.
Primary hyperoxaluria type 1
This is an autosomal recessive condition. Three forms are recognized.
Infantile form: early nephrocalcinosis and progression to CKD and end-stage renal failure (ESRF/Stage 5 CKD).
Child/adolescent form: recurrent urolithiasis and progression to ESRF.
Adult form: urolithiasis only.
Hypertension: definition
Defined by reference to sex, height centile charts (see Fig. 11.1).
Normal: systolic and diastolic <90th centile.
High normal: systolic or diastolic between 90th and 95th centile.
Hypertension: systolic or diastolic >95th centile.
Severe hypertension: systolic or diastolic >99th centile.
Blood pressure centile figures for girls and boys. Copyright Lisa Jackson and Nandu Thalange.
BP measurement should be part of routine examination.
Measurement technique
Cuff size.
bladder width—70% of acromion olecranon distance or 40%
mid-arm circumference;
bladder length—should completely encircle arm.
Note: small cuff area is a common cause of false positive high BP!
After 5min rest (ideally!).
Sitting position with arm at level of heart (children).
Supine position in infants.
On auscultation: 1st and 5th (disappearance) Korotkoff sounds used for systolic and diastolic values, respectively.
Measurement devices
Manual oscillometric sphygmomanometer (mercury now withdrawn).
Doppler: infants (for systolic pressure).
Automatic oscillometry: not all devices suitable.
Ambulatory blood pressure monitoring (ABPM) for 24-hr profiles:
little normative data in paediatrics;
significant hypertension ≥30% readings above 95th centile.
Intra-arterial (in intensive therapy unit (ITU) setting).
Hypertension: causes and features
This is a diagnosis of exclusion. High body mass index, excessive salt intake, lack of exercise, and family history may be underlying predisposing factors
Renal (commonest cause in hospital referral practice):
chronic renal parenchymal disease (reflux/scarring)
polycystic kidney disease
obstructive uropathy
acute nephritis
chronic renal failure
Vascular:
umbilical arterial/venous catheters
renal artery stenosis
renal vein thrombosis
coarctation of aorta
vasculitis
Endocrine:
congenital adrenal hyperplasia
hyperthyroidism
increased steroids (iatrogenic or endogenous)
phaeochromocytoma (BP intermittently raised)
hyperaldosteronism
Trauma
Neurological:
2° to pain
raised intracranial hypertension
Tumours:
neuroblastoma
Wilms
Medication:
steroids
aminophylline/caffeine
oral contraceptive pill
erythropoietin
calcineurin inhibitors; decongestants
amphetamines; cocaine
Others:
bronchopulmonary dysplasia
ECMO
‘white-coat’ hypertension
Clinical features
Most are asymptomatic.
Infants
Vomiting.
Failure to thrive (rare).
Congestive cardiac failure/respiratory distress (in newborns).
Children
Headache/nausea and vomiting.
Visual symptoms.
Irritable/tired.
Bell’s palsy.
Epistaxis.
Growth failure.
Fits.
Altered consciousness.
Examination
Check fundi.
Feel abdomen for abdominal masses.
Listen for renal bruits.
Feel femoral pulses and compare to radial/brachial pulses (to exclude
coarctation) and check BP in all 4 limbs.
Examination of the heart.
Investigations
A 2° cause is more likely with severe hypertension. Treatment and investigations may need to proceed together.
Urine:
urinalysis, microscopy, and culture;
vanillylmandelic acid (VMA):creatinine ratio;
steroid profile and toxicology.
Blood tests:
FBC;
U&E and creatinine;
bicarbonate, calcium, phosphate, albumin;
plasma renin and aldosterone.
CXR and ECG.
ECG.
US of urinary tract + Doppler if renal artery stenosis suspected.
Further imaging will depend upon suspected cause and ultrasound
findings, e.g. DMSA, CT scan, arteriogram.
Specialized tests, e.g. for phaeochromocytoma (see p.675).
Hypertension: management
Hypertensive crises
Acute, severe hypertension will require careful monitoring in a paediatric ICU and treatment with drugs shown in Table 11.8.
| Drug | Administration | Onset of effect | Side-effects |
|---|---|---|---|
Nifedipine | Sublingual hourly prn 200–500micrograms/kg | Minutes | Headaches,tachycardia |
Sodium nitroprusside | 0.5–10micrograms/kg/min as infusion | Seconds to minutes | Very rapid effect; titrate dose; cyanide accumulates after 48hr of use |
Labetalol | 1–3mg/kg/hr | 10–30min | Postural hypotension |
Hydralazine | Slow IV 100–500micrograms/kg | 10–30min | Tachycardia, flushes, headache |
Phentolamine | 10–100micrograms/kg | Minutes | Use in catecholamine excess states |
| Drug | Administration | Onset of effect | Side-effects |
|---|---|---|---|
Nifedipine | Sublingual hourly prn 200–500micrograms/kg | Minutes | Headaches,tachycardia |
Sodium nitroprusside | 0.5–10micrograms/kg/min as infusion | Seconds to minutes | Very rapid effect; titrate dose; cyanide accumulates after 48hr of use |
Labetalol | 1–3mg/kg/hr | 10–30min | Postural hypotension |
Hydralazine | Slow IV 100–500micrograms/kg | 10–30min | Tachycardia, flushes, headache |
Phentolamine | 10–100micrograms/kg | Minutes | Use in catecholamine excess states |
*The aim is to reduce systolic and diastolic BP to <95th centile for age and sex but, if severely hypertensive, only one-third of desired BP reduction should occur in the first 6hr. Aim for controlled reduction in BP over 72hr.
Maintenance antihypertensive therapy
Dosing schedules of many hypertensive drugs have not been evaluated in children. The favoured combination is a beta-adrenergic blocker with a vasodilator. A diuretic can be used if BP is still not controlled. ACE inhibitors should be avoided if renal artery stenosis is suspected but are useful for renin-mediated hypertension. Phentolamine is used if catecholamine-induced hypertension is suspected, e.g. phaeochromocytoma.
Table 11.9 gives dosing schedules for various hypertensive drugs.
| Drug | Administration | Dose |
|---|---|---|
Vasodilators | ||
Nifedipine | 0.25–2mg/kg/24hr | 2 divided doses |
Hydralazine | 1–7.5mg/kg/24hr | 2–3 divided doses |
Prazosin | 50–500micrograms/kg/24hr | 2–3 divided doses |
Minoxidil | 200–1000micrograms/kg/24hr | Single dose |
Beta-blockers | ||
Propranolol | 1–6mg/kg/24hr | 2–3 divided doses |
Atenolol | 1–4mg/kg/24hr | Once a day if adequate renal function |
Diuretics | ||
Furosemide | 1–5mg/kg/24hr | 1–2 divided doses |
Spironolactone | 1–3mg/kg/24hr | 1–2 divided doses |
ACE inhibitors | ||
Captopril | 0. 3–6mg/kg/24hr | 2–3 divided doses |
Enalapril | 0.1–1mg/kg/24hr | Single dose |
| Drug | Administration | Dose |
|---|---|---|
Vasodilators | ||
Nifedipine | 0.25–2mg/kg/24hr | 2 divided doses |
Hydralazine | 1–7.5mg/kg/24hr | 2–3 divided doses |
Prazosin | 50–500micrograms/kg/24hr | 2–3 divided doses |
Minoxidil | 200–1000micrograms/kg/24hr | Single dose |
Beta-blockers | ||
Propranolol | 1–6mg/kg/24hr | 2–3 divided doses |
Atenolol | 1–4mg/kg/24hr | Once a day if adequate renal function |
Diuretics | ||
Furosemide | 1–5mg/kg/24hr | 1–2 divided doses |
Spironolactone | 1–3mg/kg/24hr | 1–2 divided doses |
ACE inhibitors | ||
Captopril | 0. 3–6mg/kg/24hr | 2–3 divided doses |
Enalapril | 0.1–1mg/kg/24hr | Single dose |
