Spontaneous rib fractures in a black woman with familial hypocalciuric hypercalcemia

Familial hypocalciuric hypercalcemia (FHH) is a rare but important consideration in the differential diagnosis of hypercalcemia. FHH results from an autosomal dominantly inherited inactivating mutation of the calcium sensing receptor (CaSR) gene and is typically associated with a benign clinical course and normal bone mineral density.

We describe the unusual case of a 57-year old African American woman with spontaneous rib fractures who was found to have FHH due to a novel set of polymorphisms of the CaSR gene. She also had hypertension, esophageal reflux disease treated with proton pump inhibitors, osteopenia by DEXA scanning, and a prior left ankle fracture in the absence of significant trauma. There was no suggestive family history and her only sibling had a normal serum calcium. The patient was evaluated extensively for potential causes of osteoporotic fractures.

It is imperative to screen for FHH using 24-hour urinary calcium and creatinine excretion in subjects with hypercalcemia irrespective of ethnicity and a history of non-traumatic rib fractures. This approach may prevent unnecessary neck exploration for parathyroidectomy which is unwarranted in FHH.