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. Laboratory findings revealed
calcium 15.8 mg/dL (8.4-10.2), albumin 4.1 g/dL (3.8-4.8), and parathyroid
hormone 62 pg/mL (14-64). Serum calcium improved after intravenous hydration
with normal saline. Prior to this hospitalization, over-the-counter medications
were significant for calcium (600 mg daily), vitamin A (11 000 IU daily), and
vitamin D (800 IU daily).The patient’s prescription medications were significant
for hydrochlorothiazide (12.5 mg daily). Twenty-four-hour urine calcium was
subsequently found to be 146 mg (35-250). Myeloma, lymphoma, and sarcoidosis
were ruled out as the etiology for hypercalcemia. The diagnosis of primary
hyperparathyroidism was confirmed. She was treated surgically for primary
hyperparathyroidism. The right and left superior parathyroid showed
hypercellular parathyroid on pathology. The patient was normocalcemic after
surgery. Conclusion. Previous reports suggest that very high
doses of vitamin A is required to cause hypercalcemia. This case suggests that
in a setting of primary hyperparathyroidism and hydrochlorothiazide therapy,
vitamin A may contribute to the development of severe hypercalcemia in patients
who are on calcium and vitamin D supplements. Given their biologic effects,
public awareness needs to be created regarding the injudicious use of
vitamins.