Hypercalcemia in a Patient with Primary Hyperparathyroidism and Acromegaly: Distinct Roles of Growth Hormone and Parathyroid Hormone in the Development of Hypercalcemia

Abstract

We herein report a case of primary hyperparathyroidism associated with acromegaly. Although serum parathyroid hormone (PTH) levels increased after the resection of a pituitary adenoma, levels of serum 1á, 25-dihydroxyvitamin D [1, 25(OH)₂D] decreased but remained above the normal upper limit. After resection of a parathyroid adenoma, serum PTH, 1, 25(OH)₂D, calcium (Ca), and phosphate were all normalized. Since serum 1, 25(OH)₂D levels decreased in spite of the increase in serum PTH levels after normalization of levels of growth hormone (GH), GH may have contributed to the elevation of serum 1, 25(OH)₂D. It is therefore suggested that the mechanism by which elevation of serum 1, 25(OH)₂D occurred in the present case may involve an increase in serum GH distinct from the PTH-mediated pathway.