Hypercalcemia Unmasking Several Underlying Disorders After Vitamin D Supplementation: A Case Report

Vitamin D intoxication is a common initial consideration when hypercalcemia develops in patients receiving vitamin D supplementation [2,7]. The differential diagnosis of hypercalcemia is broad and includes primary hyperparathyroidism and malignancy as the common causes [1,7]. Less commonly, granulomatous disorders such as sarcoidosis lead to hypercalcemia through dysregulated extrarenal synthesis of 1,25-dihydroxyvitamin D by activated macrophages within granulomas [3,7]. Measurement of parathyroid hormone (PTH) is central to etiologic classification: elevated PTH suggests primary hyperparathyroidism, whereas suppressed PTH indicates PTH-independent hypercalcemia, which may result from malignancy, granulomatous disease, vitamin D excess, or other less common causes [1,7].