Low 24-hour Urine Calcium Levels in Patients with Sporadic Primary Hyperparathyroidism: Is Further Evaluation Warranted Prior to Parathyroidectomy?

Abstract Background Low 24-hour urine calcium (uCa) levels in patients with primary hyperparathyroidism (pHPT) raise concern for familial hypocalciuric hypercalcemia. This study evaluated patients with a low 24-hour uCa level for potential differences that may guide the extent of preoperative evaluation needed. Methods A retrospective review was conducted of 1,139 sporadic pHPT patients who underwent parathyroidectomy between December 1999 and May 2011. Results Of the 54 (5%) patients with greater than or equal to one low 24-hour uCa ( P = .0011) and glomerular filtration rate ( P = .0007). Conclusion This study suggests that sporadic pHPT patients with low 24-hour uCa levels may not require further evaluation with genetic testing for familial hypocalciuric hypercalcemia, especially if previous eucalcemia is documented.