Cinacalcet-Associated Resolution of Primary Hyperparathyroidism in a Patient With Normal Kidney Function

Cinacalcet use is associated with risk of hypocalcemia; however, this risk has been mostly demonstrated in patients with chronic kidney disease. In this article, we describe a case of a 59-year-old male with primary hyperparathyroidism (PHPT), hypercalciuria, osteopenia, and normal kidney function who was started on cinacalcet for the management of recurrent hypercalcemia following prior unsuccessful parathyroidectomy. Within 6 months following cinacalcet commencement, he developed symptomatic and biochemical hypocalcemia requiring discontinuation of the medication and initiation of calcium supplementation. Over more than 3 years of follow-up, his calcium supplementation was gradually tapered off and then discontinued. He is presently eucalcemic and euparathyroid off calcium supplements while also demonstrating normalization of hypercalciuria and bone mineral density. These data indicate that our patient has experienced resolution of PHPT after brief exposure to cinacalcet. We recommend that low starting cinacalcet doses should be considered for treatment of hypercalcemia in patients with PHPT who underwent unsuccessful parathyroidectomy along with close clinical and biochemical follow-up.