Vitamin A and Hydrochlorothiazide Causing Severe Hypercalcemia in a Patient With Primary Hyperparathyroidism.

Objective: To report a case of severe hypercalcemia, exacerbated by vitamin A supplementation and hydrochlorothiazide, in a patient with primary hyperparathyroidism.

Methods: Clinical and laboratory findings are presented along with response to therapy.

Results: A 68-year-old white female presented to the emergency department complaining of nausea, vomiting, and altered mental status.