Long-term follow-up of patients with hypoparathyroidism.

CONTEXT: Despite tremendous interest in hypoparathyroidism, large cohort studies describing typical treatment patterns, laboratory parameters, and rates of complications are lacking.

OBJECTIVE: Our objective was to characterize the course of disease in a large cohort of hypoparathyroid patients.

DESIGN AND SETTING: We conducted a chart review of patients with permanent hypoparathyroidism identified via a clinical patient data registry. Patients were seen at a Boston tertiary-care hospital system between 1988 and 2009.

PATIENTS: We identified 120 patients. Diagnosis was confirmed by documented hypocalcemia with a simultaneous low or inappropriately normal PTH level for at least 1 yr. Mean age at the end of the observation period was 52 ± 19 (range 2-87) yr, and the cohort was 73% female.

MAIN OUTCOME MEASURE: We evaluated serum and urine laboratory results and renal and brain imaging.

RESULTS: We calculated time-weighted average serum calcium measurements for all patients. The time-weighted average for calcium was between 7.5 and 9.5 mg/dl for the majority (88%) of patients. Using linear interpolation, we estimated the proportion of time within the target calcium range for each patient with a median of 86% (interquartile range 67-98%). Of those with a 24-h urine collection for calcium (n = 53), 38% had at least one measurement over 300 mg/d. Of those with renal imaging (n = 54), 31% had renal calcifications, and 52% of those with head imaging (n = 31) had basal ganglia calcifications. Rates of chronic kidney disease stage 3 or higher were 2- to 17-fold greater than age-appropriate norms.

CONCLUSIONS: Hypoparathyroidism and its treatment carry a large burden of disease. Renal abnormalities are particularly common.