Received on March 14, 2006
Accepted on October 3, 2006

Endocrinology and Metabolism

University of Virginia Case Conference: Persistent Hypercalcemia After Parathyroidectomy in an Adolescent and Effect of Treatment With Cinacalcet HCl

¹ Department of Pathology, University of Virginia Medical School, Charlottesville, VA
² Department of Pediatrics, University of Virginia Medical School, Charlottesville, VA
³ Centre de recherché du CHUM, Hôpital Saint-Luc, Montréal, Québec
⁴ Department of Pediatric Endocrinology, Division of Pediatrics, The Children's Hospital at the Cleveland Clinic, Cleveland, OH
⁵ Department of Surgery, University of Virginia Medical School, Charlottesville, VA

^* To whom correspondence should be addressed. E-mail: lmh5p{at}virginia.edu.

Background: Hyperparathyroidism is uncommon in adolescence and is more likely to persist after parathyroidectomy than in adults. Cinacalcet HCl is a new calcimimetic that has been used successfully for the treatment of primary and secondary hyperparathyroidism in adults, but its use in adolescents has not been reported.

Case: A 16 year-old male presented with hypercalcemia that had persisted for 1.5 years after parathyroidectomy for primary hyperparathyroidism. Parathyroid hormone (PTH) concentrations were nonsupressed despite a mean (SD) serum calcium concentration of 2.82 (0.06) mmol/L. Treatment with cinacalcet HCl was initiated and a pharmacodynamic profile was obtained for serum calcium, phosphorus, and PTH. Cinacalcet HCl normalized serum calcium. The changes in PTH were assay dependent.

Issues: We use this case conference to review the evaluation of hypercalcemia in adolescents, examine the changes in relevant laboratory results during treatment with cinacalcet HCl, and discuss differences among assays for PTH.

Conclusions: Interpretation of PTH results in patients treated with cinacalcet HCl requires consideration of the pharmacodynamic effects of the drug and the nature of the PTH assay.