Successful Parathyroidectomy May Not Resolve Hypercalciuria in Patients With Primary Hyperparathyroidism

Background: Hypercalciuria, with twenty-four-hour urinary calcium of >400 mg/day, is one of the indications for parathyroidectomy in patients with primary hyperparathyroidism. We report five cases where hypercalciuria is not resolved following a successful parathyroidectomy (normalization of serum calcium) in such patients. Here resolution of hypercalciuria is defined as twenty-four-hour urinary calcium of less than 200 mg/day. Clinical Case: This is a case series of five patients who remained hypercalciuric at 6 to 19 months after successful parathyroidectomy. Pre-parathyroidectomy, average PTH was 95 pg/dL (Min 69 pg/dL, Max 120 pg/dL), average serum calcium was 11.0 mg/dL (min 10.3 mg/dL, max 12.0 mg/dL), and average twenty-four-hour urinary calcium was 455 mg/day (min 386 mg/day, max 551 mg/day). Calcium levels were corrected to normal range post-parathyroidectomy and remained in normal range. However, hypercalciuria did not resolve. Post-parathyroidectomy, average PTH was 44 pg/dL (min 25 pg/dL, max 69 pg/dL), average serum calcium was 9.6 mg/dL (min 9.3 mg/dL, max 9.8 mg/dL), and average twenty-four-hour urinary calcium was 284 mg/day (min 201 mg/day, max 376 mg/day). Two patients who had history of nephrolithiasis prior to parathyroidectomy continued to develop nephrolithiasis at six and sixteen months after successful parathyroidectomy. Conclusions: This case series showed that hypercalciuria may not resolve following a successful parathyroidectomy in patients with primary hyperparathyroidism and elevated twenty-four-hour urinary calcium at 6 to 19 months after surgery. Further observations to evaluate long term effects of parathyroidectomy on hypercalciuria is needed.