Response to Letter to the Editor From Candemir and Çakal: “24-Hour Urine Calcium Predicts Reduced Fracture Incidence and Improved Bone Mineral Density After Surgery for Primary Hyperparathyroidism”

Dear Editor and valued readers,

We are most grateful for this opportunity to straighten out the issues pointed out by Candemir and Çakal (1).

In our setting, patients with suspected primary hyperparathyroidism (pHPT) are thoroughly evaluated at the Department of Endocrinology in their local or regional hospital. After the diagnosis has been established, including the exclusion of hereditary and malabsorptive disorders, patients are referred to our department for surgical consultation. Patients have been advised to undergo surgical treatment if they met the international guidelines that were in place at the given time (as described in Bilezikian et al 2022, Table 2) (2), but surgical treatment has also been provided according to the patient's choice after individual evaluation of potential benefits and risk. Any redo procedures have been carefully discussed with the patient.

The 24-hour urinary calcium levels are typically only measured during the diagnosis workup at the Department of Endocrinology and have likely not been reevaluated after vitamin D replacement therapy. However, vitamin D deficiency is relatively common in Sweden, especially in certain populations (obese and those with origin outside Europe) (3), so it cannot be excluded that vitamin D deficiency, untreated at the time 24-hour urinary calcium was measured, might confound its association with fracture incidence.

In a post hoc analysis in our cohort using Fracture Risk Assessment Tool (FRAX) with a Swedish nomogram (4), a female pHPT patient of mean age, height, and weight without previous fracture history experienced only a slightly reduced 10-year hip fracture risk from 2.0% to 1.9% one year postoperatively, given the mean bone mineral density improvement in the femoral neck and not taking into account any other risk factors. Similarly, a male patient without previous fracture history and other risk factors, experienced a moderate fracture risk reduction from 1.5% 10-year hip fracture risk to 1.2% one year postoperatively, and major osteoporotic fracture risk 6.6% before vs 6.2% after surgery. It should be noted that FRAX likely underestimates the fracture risk for pHPT patients, as the disease predominantly affects cortical bone.

Disclosures

None.

References

Abbreviation

 
• pHPT

  primary hyperparathyroidism