Nephrocalcinosis, Renal Dysfunction, and Calculi in Patients With Primary Hypoparathyroidism on Long-Term Conventional Therapy

Context: There are concerns about the long-term safety of conventional therapy on renal health in patients with hypoparathyroidism. Careful audit of these would help comparisons with upcoming parathyroid hormone therapy.

Objective: We investigated nephrocalcinosis, renal dysfunction, and calculi, their predictors and progression over long-term follow-up in patients with primary hypoparathyroidism (PH).

Design and setting: An observational study at a tertiary care center was conducted.

Participants and methods: A total of 165 PH patients receiving conventional therapy were evaluated by radiographs, ultrasonography, and computed tomography. Their glomerular filtration rate (GFR) was measured by Tc-99m-diethylenetriamine penta-acetic acid clearance. Clinical characteristics, serum total calcium, phosphorus, creatinine, hypercalciuria, and fractional excretion of phosphorus (FEPh) at presentation and during follow-up were analyzed as possible predictors of renal complications. Controls were 165 apparently healthy individuals.

Results: Nephrocalcinosis was present in 6.7% of PH patients but not in controls. Patients younger than 15 years at presentation and with higher serum calcium-phosphorus product were at higher risk. Nephrocalcinosis showed no significant association with cataract and intracranial calcification. Prevalence of renal calculi was comparable between hypoparathyroid patients and controls (5% vs 3.6%, P = .58). Fourteen percent of patients had a GFR less than 60 mL/min/1.73 m2. Increased FEPh during follow-up was the significant predictor of low GFR. Nephrocalcinosis developed in 9% of patients over 10 years of conventional therapy.

Conclusion: A total of 6.7% of PH patients had nephrocalcinosis, and 14% showed renal dysfunction. Prevalence of renal calculi was similar in patients and controls. Nine percent of patients developed nephrocalcinosis over 10 years of conventional therapy.