Endocrine Disorders with Parathyroid Hormone-Independent Hypercalcemia.

The most common causes of hypercalcemia are primary hyperparathyroidism and malignancy, constituting 80% to 90% of all cases. Although less common, several nonparathyroid endocrine disorders are associated with hypercalcemia. The most well described is hyperthyroidism, although the reported prevalence of hypercalcemia in hyperthyroid patients varies depending on applied method for measuring serum calcium levels. Also, adrenal insufficiency, pheochromocytoma, and vasoactive intestinal polypeptide are associated with hypercalcemia. These are differential diagnoses when assessing the hypercalcemic patient for whom common causes have been excluded. Further investigation is needed regarding hypothyroidism; acromegaly, hyperprolactinemia, gonadal dysfunction, and diabetes are not associated with hyperthyroidism.