Endocrine Abstracts

Introduction: Familial hypocalciuric hypercalcemia (FHH) is a benign disorder, with inappropriately elevated parathyroid hormone, without the complications of hypercalcemia (1). It is important to discriminate FHH from primary hyperparathyroidism (PHPT), because of the consequences on symptomatic disease and therapeutic approach. Ca/Cr clearance ratio will be <0.01 in FHH and most often >0.02 in PHPT (2). In patients with PHPT and vitamin D deficiency, low urinary calcium will increase after vitamin D repletion, thereby differentiating it from FHH.

Case reports: Five female patients, mean age 54.4 years, without specific clinical symptoms had elevated PTH (mean value 89.2 pg/ml), elevated or at the upper limit of normal serum calcium (10.3 mg/dl) and low urine calcium (mean value 80.5 mg/24 h). Their Ca/Cr clearance ratio was <0.01 (mean value 0.006). Vitamin D 25 OH deficiency coexisted in 2 patients was supplied without substantial increase in calcium urine values. The lack of symptoms and Ca/Cr clearance ratio <0.01 confirmed the diagnosis of FHH. No further evaluations and treatment was necessary.

Conclusion: In clinical practice, frequently we see elevated levels of PTH and serum calcium, which can lead to unnecessary evaluation and unsuccessful treatment if not FHH is considered.