14 Renal medicine and urology

Commonly ordered test to detect renal dysfunction. Rough guide to glomerular filtration rate (GFR) when corrected for age, gender, and weight—↓ in GFR is associated with ↑ in serum creatinine. Causes of an abnormal serum creatinine—see Table 14.1.

More sensitive measure than serum creatinine to assess renal function. Calculated from:

Changes in eGFR can be used to monitor changes in kidney function.

Commonly ordered test to detect renal dysfunction. While ↓ in GFR is associated with ↑ in serum urea, serum urea may also vary independently of the GFR. Causes of abnormal serum urea—see Table 14.1.

High serum potassium (>5mmol/L). Causes: See Table 14.2. Treat the cause.

Tall tented T-waves; small P-wave; wide QRS complex becoming sinusoidal VF.

Low serum potassium (<3.5mmol/L). Presents with muscle weakness, hypotonia, cardiac arrhythmias, cramps, and tetany. Causes: see Table 14.2. If K⁺ >2.5mmol/L and no symptoms, give oral potassium supplement. If the patient is taking a thiazide diuretic, hypokalaemia >3.0mmol/L rarely needs treating.

Small/inverted T-waves; prominent U-wave; prolonged P-R interval; depressed ST segment.

Low serum sodium (<135mmol/L). Rarely symptomatic in general practice. May present with signs of water excess— confusion, fits, ↑ BP, cardiac failure, oedema, anorexia, nausea, muscle weakness. Causes: see Table 14.2. Management: treat the cause. If unwell admit for investigation.

Excess serum sodium (>145mmol/L). Rare in general practice. Presentation: thirst, confusion, coma, fits, signs of dehydration—dry skin, ↓ skin turgor, postural hypotension, and oliguria if water deficient. Causes: see Table 14.2. Management: admit for investigation.

See Table 14.3. Renal disease may present with:

Normally detected with urine dipstick. If +ve, then repeat with another sample to exclude spurious results, and send sample for M,C&S to exclude UTI. Treat the cause where necessary. Causes:

Albuminuria in the range 30–200 mg/L. Not detectable with standard urine dipsticks. Special sticks are available for routine screening of high-risk groups, e.g. diabetics. Causes:

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Proteinuria, hypoalbuminaemia, and oedema. Often associated with ↑ cholesterol. Causes:

Swelling of eyelids and face; ascites, peripheral oedema; urine froth due to protein. Nephrotic crisis: unwell with oedema, anorexia, vomiting, pleural effusions, and muscle wasting.

Urine—total protein:creatinine ratio (TPCR) >200mg/mmol; microscopy for red cells, casts; Blood—U&E, creatinine, eGFR, albumin (<25g/L), cholesterol, FBC, ESR.

Refer all suspected cases of nephrotic syndrome to a renal physician. Complications include:

Central feature is blood and protein in the urine from glomerular inflammation.

Deposition of Ca²⁺ in the kidneys. X-ray— calcification. May cause symptoms of UTI or renal stones. Causes:

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Distressing desire to pass something per urethra that will not pass, e.g. stone.

Urine output <400mL/24h. Causes: dehydration, cardiac failure, ureteric obstruction, renal failure.

Also known as acute renal failure (ARF). ↓ renal function over hours/days ± oliguria/anuria. Refer immediately if acute ↑ in urea/creatinine or ↓ in eGFR (to <60mL/min/1.73m² if normal in last 3mo, or ↓ of >15% over 5d). Causes: acute tubular necrosis (80%—due to acute circulatory compromise); renal tract obstruction (5%); GN.

Also known as chronic renal failure (CRF). Slow ↓ renal function over months/years. Causes:

—see Table 14.4

If sudden ↓ in renal function (↓ eGFR of >15% between tests or >5mL/min/1.73m² in <1y or >10mL/min/1.73m² in <5y) suspect infection, dehydration, uncontrolled ↑ BP, metabolic disturbance (e.g. ↑ Ca²⁺), obstruction, nephrotoxins (e.g. drugs). If unable to find cause or treatment does not ↑ renal function, refer.

To a renal physician if:

80 new patients/million population/y. Irreversible. Dialysis starts when GFR is 10–15% normal. Dialysis is needed lifelong unless a kidney transplant becomes available. Refer back to the renal unit managing the patient if you have any problems.

Blood flows opposite dialysis fluid and substances are cleared along a concentration gradient across a semi-permeable membrane. Problems: pulmonary oedema; infection (HIV, hepatitis, bacteria); U&E imbalance; BP ↓ or ↑; problems with vascular access; dialysis arthropathy (especially shoulders and wrists); aluminium toxicity; time.

A permanent catheter is inserted into the peritoneum via a subcutaneous tunnel. ~2L dialysis fluid is introduced and kept in the peritoneum. This is changed for fresh fluid up to 5x/d at home. Does not tie the patient to a dialysis machine. Problems: peritonitis; catheter blockage (refer as an emergency); weight ↑; poor DM control; pleural effusion; leakage.

2° anaemia due to ↓ kidney erythropoietin production is universal amongst people with ESRD. Exclude other causes. Recombinant erythropoietin is given if Hb <10.5g/dL (75%).

Transplanted kidneys are usually sited in an iliac fossa. 5y graft survival is ~88% for adults. Closer genetic matches have better survival rates. Problems:

Important cause of renal failure. Associated with inflammatory cell infiltration of the renal interstitium/tubules. Causes:

Presents with AKI/CKD, raised temperature, arthralgia, eosinophilia. Patients with AKI have good prognosis. Those with CKD have gradual deterioration over time.

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Caused by prolonged heavy use of analgesics (including NSAIDs). Presents with an interstitial nephritis-like picture. Associated with ↑ incidence of UTI. Carcinoma of the renal pelvis is a rare complication. Investigate promptly if the patient develops haematuria.

Types and presentation—see Table 14.5. Refer all suspected cases urgently to a renal physician. Terminology:

Presents as CKD or one of its complications. Probably arises from UTIs, vesico-ureteric reflux and consequent renal scarring in childhood ( p. 878). Refer to a renal physician.

Autosomal dominant disease (1:1,000). Cysts develop in the kidney causing gradual ↓ in renal function. Common cause of CKD. Presents with haematuria, UTI, abdominal mass (30% have cysts in the liver/pancreas too), lumbar/abdominal pain, and/or ↑ BP. May be associated with mitral valve prolapse and SAH/berry aneurysms. USS shows large kidneys with multiple cysts. Refer to a renal physician if CKD 3–5. Treat infections and ↑ BP. Check family members (though cysts may not be seen <30y). 45% progress to ESRD by 60y.

Developmental abnormality of the medullary pyramids of the kidney, characterized by dilatation of the renal collecting tubules. ♂ > ♀. There may be a family history. Most are asymptomatic and the condition is an incidental finding. If symptomatic, presents with UTIs, renal stones, haematuria. Refer if symptomatic. Usually prognosis is very good and most require no treatment.

Causes: nephrotic syndrome (15–20% develop RVT); membranous GN (30%); acute dehydration. Presentation varies from no symptoms to severe pain and loin tenderness. Suspect in at-risk individuals if unexplained loss of renal function and RBCs in urine. Refer to a renal physician for further investigation.

Causes: atheroma, fibromuscular hyperplasia (in the young). Presents with ↑ BP (may be severe or drug-resistant); vascular disease elsewhere; abdominal bruit; ↑ Cr, ↓ eGFR, and proteinuria. If bilateral or extensive, renal failure may be precipitated by dehydration, ↓ BP, or drugs (ACE/ARB initiation; NSAIDs). Refer to a renal physician (if diagnosis is unsure) or vascular surgeon (if diagnosis is known).

X-linked or autosomal inherited disease. Congenital sensorineural deafness, haematuria, proteinuria, and renal failure. Associated with lens abnormalities, platelet dysfunction, and ↑ BP. Causes ESRD by third decade in ♂; ♀ rarely develop ESRD. Renal failure does not recur after transplantation. A.C. Alport (1880–1959)—South African physician.

12% of ♂ and 3% of ♀ will develop a renal stone at some point; peak age 20–50y. Symptoms are not dependent on size of the stone.

Acetazolamide, allopurinol, aspirin, steroids, indinavir, nelfinavir, loop diuretics, probenecid, quinolones, sulfonamides, theophylline, thiazides, triamterene, antacids, calcium/vitamin D supplements, high-dose vitamin C.

Usually presents with pain ± nausea/vomiting. Location and type of pain gives clues about the site of the stone:

UTI, haematuria, retention, renal failure (rare).

Pyelonephritis; ruptured AAA; cholecystitis; pancreatitis; appendicitis; diverticulitis; obstruction; strangulated hernia; testicular torsion; pethidine addiction.

Dipstick urine if possible. Absence of RBCs does not exclude renal colic but consider alternative diagnosis.

Stones usually pass spontaneously. Give pain relief (diclofenac 75mg IM/100mg PR) ± antiemetic. Consider admission to hospital if:

Encourage ↑ fluid intake; sieve urine for stones. Monitor/review pain relief and for complications.

Can wait until the next working day and include:

50% recur in 5–7y. Give general advice on prevention of stones (see Table 14.6). If investigations show any loss of renal function, renal obstruction, or remaining stones—refer to urology. Dependent on composition of stones, give dietary advice/refer to dietician (see Table 14.6).

May be 1° (autosomal recessive condition) or 2° to gut resection/malabsorption or dietary excess of spinach or vitamin C. Take specialist advice on management. There are two types of 1° hyperoxaluria:

Most common aminoaciduria. Usually presents with stones at age 10–30y. Urine: cystine ↑, ornithine ↑, arginine ↑, lysine ↑. Take specialist advice on management.

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Hypercalciuria may occur without hypercalcaemia and is found in ~ 80% of patients with calcium oxalate stones.

Blood in the urine. Causes—see Table 14.7.

Presence of white cells in the urine in the absence of UTI. Causes:

Initially repeat with clean-catch MSU. If finding persists refer to urology.

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Incidence: 10,540 cases/y in the UK; ♂:♀ ≈5:2. Transitional cell carcinoma (TCC) is most common in the UK—squamous cell carcinoma (SCC) is most common worldwide. Risk factors:

Haematuria—painless or painful. Less commonly:

MSU—excludes UTI and detects sterile pyuria and/or microscopic haematuria.

Refer urgently to urology to be seen in <2wk. Treatment depends on stage at diagnosis—see Table 14.8.

Clear cell adenocarcinoma of renal tubular epithelium. Incidence: 9,300 cases/y in the UK. Typical age: 50y. ♂:♀ ≈1.5:1. Spread can be local or haematogenous (bone, liver, lung—causes cannon ball metastases seen on CXR).

Urine: RBCs. Blood:↑ PCV (2%), anaemia, hypercalcaemia. Radiology: USS, CXR.

Refer to urology urgently to be seen in <2wk. Treatment includes surgery where possible ± chemotherapy, radiotherapy, and/or biological therapy. Overall 50% 5y survival.

Urinary tract infection (UTI) is one of the most common conditions seen in general practice, accounting for up to 6% of consultations (one case/average surgery). ♀ > ♂. 20% of women at any time have asymptomatic bacteriuria and 20–40% of women will have a UTI in their lifetime.

E. coli (>70%), Proteus spp., Pseudomonas spp., streptococci, staphylococci.

Painful micturition resulting from urethral or bladder inflammation. Causes: UTI, urethral syndrome, inflammation (e.g. interstitial cystitis, radiation-induced cystitis), intravesical lesion (tumour, stone), atrophy (menopause).

Passage of urine more often than usual. Causes:

If uncomplicated UTI in an otherwise healthy woman, test urine with a leucocyte and nitrite dipstick. If +ve, treat for UTI. Reasons to send MSU for M,C&S:

For women with severe or 3 or more symptoms of cystitis, start treatment without urine dipstick. Take MSUs prior to starting antibiotics—send to the laboratory fresh. Consider chlamydia infection in young men or women with symptoms of UTI.

Consider further investigation with blood tests (U&E, Cr, eGFR, and/or PSA if >40y and ♂) and/or radiology (e.g. renal tract USS, KUB) if:

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— p. 812

— p. 878

Reinfection after successful treatment of infection (90%) or relapse after inadequate treatment.

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Symptoms of cystitis with −ve MSU. Unknown cause. Associated with cold, stress, nylon underwear, CHC, and intercourse. Advise fluids ++ and to wear cotton underwear. Consider changing/stopping CHC or trying topical oestrogen if post-menopausal. Tetracyclines (e.g doxycycline 100mg bd for 14d) or azithromycin (500mg od for 6d)^R are helpful in some. If not settling, refer to urology. Urethral dilatation/massage may be helpful.

Predominantly middle-aged women. Can cause fibrosis of the bladder wall. Main symptoms—frequency, urgency, and pelvic/suprapubic pain especially when the bladder is full. Often misdiagnosed as recurrent UTI. MSU—no bacteriuria. Refer to urologist for confirmation. There is no satisfactory treatment, though antispasmodics, amitriptyline, and bladder stretching under GA may help some patients.

Involuntary loss of urine which is objectively demonstrable and a social or hygienic problem. 1 in 3 with incontinence consult at outset, 1 in 3 consult later, 1 in 3 suffer in silence. Opportunistic questioning can identify sufferers.

Intake/output diary (at least 3d, including working and leisure days)—evaluates problem and benchmark for progress—record drinks and passage of urine; urine—RBCs, MC&S; consider blood for U&E, eGFR, FBC, FBG/HbA1c if renal impairment/DM is suspected.

Diuretics, antihistamines, anxiolytics, α-blockers, sedatives and hypnotics, anticholinergic drugs, TCAs.

30% have a mixed pattern. Treat according to dominant symptom. Try general measures before referring to urology/gynaecology or for further investigations (see Table 14.9).

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Detrusor instability or hyperreflexia cause the bladder to contract unintentionally

Constant dribbling loss day and night. Causes: BPH, prostate cancer, urethral stricture, faecal impaction, neurological (LMN lesions), side effect of medication. Treatment is aimed at relieving the obstruction ( p. 454).

Communication between bladder and the outside—normally through the vagina. Results in constant dribbling loss day and night. Refer to gynaecology/urology. Causes: congenital, malignancy, complication of surgery.

No urological problem. Caused by other factors, e.g. inaccessible toilets/immobility, behavioural problems, cognitive deficit. Treat the cause.

Many different types. DNs or continence advisors are best aware of those available via the NHS locally. They are not available on FP10 and supplied by local NHS Trusts on a ‘daily allowance’ basis. This varies across the country.

Absorb 1–4L of urine. Good laundry facilities are needed. If left wet can cause skin breakdown. Available via NHS Trusts.

Can be prescribed on NHS prescription. Approved appliances are listed in part IXB of the UK Drug Tariff. Used for men who have intractable incontinence and who are highly physically dependent, do not have urine retention and do not require an internal catheter. Assessment and fitting by a DN or continence adviser is essential.

Used in association with a drainage bag. Sheaths may be non-adhesive, self-adhesive or attached with adhesive strips. Adhesive sheaths can last several days but daily changing is recommended. Replace non-adhesive sheaths 2–3x/d (some are reusable).

Include ↑ susceptibility to UTI, sores on penis, and skin irritation due to the adhesive.

Can be prescribed on NHS prescription. Approved appliances are listed in part IXA of the UK Drug Tariff.

Only use catheters in patients who have:

Only long-term Foley catheters are suitable for use in primary care. They last 3–12wk.

Unless specified a 12 or 14Ch catheter is supplied. Use the smallest diameter of catheter that drains urine effectively. Catheters >16Ch are more likely to cause bypassing of urine around the catheter and urethral strictures.

Men require longer catheters than women. Specify ‘male’ or ‘female’ on the prescription.

10mL balloons are supplied unless specified otherwise. Pre-filled catheters contain sterile water which inflates the retaining balloon with water. They are more expensive but quicker to insert and there are no costs for syringes or sterile water.

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Usually attached to a leg bag, although catheter valves are also available allowing the patient to use his/her bladder as a urine reservoir. The valve must be released every 3–4h to drain out the urine.

Patient inserts a catheter into his/her bladder 4–5x/d to drain urine. ↓ problems of infection and blockage. Useful for neurological bladder dysfunction. Types:

Can be prescribed on NHS prescription. Approved appliances are listed in part IXB of the UK Drug Tariff.

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(See Figure 14.1) Obstruction may be unilateral (kidney, pelvi-ureteric junction, or ureter) or bilateral (bladder, urethra, prostate). Unilateral obstruction may present late if the other kidney remains functioning. Suspect if loin ache worsened by drinking. Confirm with USS and refer to urology. Obstructing lesions may be in the lumen (e.g. stones) in the wall (e.g. tumours) or impinging from outside (e.g. retroperitoneal fibrosis).

Sudden inability to pass urine → lower abdominal discomfort with inability to keep still. Differentiate from AKI. ♂ > ♀. Risk factors: age >70y; symptoms of prostatism/poor urinary stream.

Prostatic obstruction (82%); constipation; alcohol; drugs (anticholinergics, diuretics); UTI; operation (e.g. hernia repair). Rarer causes: urethral stricture; clot retention; spinal cord compression; bladder stone.

Abdomen—palpable bladder; DRE—enlarged ± irregular prostate; perineal sensation to exclude neurological cause.

MSU to exclude infection. Blood for U&E, Cr, and eGFR. Only investigate if catheterizing in the community.

Catheterize (record initial volume drained) or refer to urology for catheterization—local policies vary. Treat infection. Refer to DN for instruction on management of the catheter. Refer to urology for further assessment and treatment.

Insidious onset. Causes: benign prostatic hypertrophy; pelvic malignancy; CNS disease. May present as:

As for acute retention. Bladder is enlarged (may contain >1.5L) but usually non-tender.

Refer to urology for further assessment and treatment. Refer urgently or acutely if pain, UTI or renal failure (eGFR <60mL/min/1.73m²). Do not catheterize in the community.

Ureters become embedded in dense fibrous plaques in the retroperitoneal space. Associations:

Typically middle-aged men presenting with fever, malaise, sweating, leg oedema, ↑ BP, palpable mass, and/or acute/chronic renal failure. Refer for specialist care. Options include steroids and nephrostomies.

Congenital abnormality. Kidneys are fused in the midline to form a horseshoe-shaped mass. The kidney may function normally or may present with obstructive nephropathy or UTIs.

10–30% of men in their early 70s have symptomatic benign prostatic hypertrophy (BPH). There is no relation between size of the prostate and symptoms. Assessment—see Table 14.10.

10% at presentation:

Symptoms can improve spontaneously but overall progress slowly. 1–2%/y develop urinary retention. Options:

Patients with mild to moderate symptoms at presentation, with no complications of BPH and who are not severely troubled by their symptoms. Self-help includes: ↓ evening fluid intake, ↓ caffeine intake, bladder retraining, and prevention of constipation.

Those with mild/moderate symptoms who are troubled by their symptoms. Consider:

Serenoa repens (saw palmetto) has no benefit over placebo^C.

E = Emergency admission; U = Urgent; S = Soon; R = Routine.

Consider in men presenting with suspected UTI. Other features: fever; arthralgia/myalgia; low back, perineal, penile ± rectal pain. DRE reveals swollen, tender prostate. If suspected, check MSU and treat with 4wk course of oral antibiotic which penetrates prostatic tissue, e.g. ciprofloxacin 500mg bd, ofloxacin 200mg bd. Refer for specialist advice if not settling. Complications include: acute retention of urine, chronic bacterial prostatitis, and prostate abscess.

2–14% lifetime prevalence. Cause is unknown. Presents with >3mo history of:

Diagnosis is based on history with exclusion of other causes. Suitable investigations include DRE, MSU, urine cytology, STI screen ( p. 739), PSA ± urodynamic studies. Treatment is difficult—provide information and support; try α-blockers (e.g. doxazosin 4mg od for 6mo). Spontaneous improvement/remission often occurs.