Hypercalcemia and acromegaly--clarifying the connections. A case report and review of the literature.
OBJECTIVE
Hypercalcemia in patients with acromegaly is rare and usually due to co-existent primary hyperparathyroidism. The etiology of hypercalcemia directly related to acromegaly is debated.


METHODS
We present a case report of 1,25(OH)2D3-mediated hypercalcemia in a patient with acromegaly and discuss potential pathophysiological mechanisms contributing to the development of hypercalcemia late in the course of the disease.


RESULTS
A 67-year-old female presented with classical features of acromegaly. A review of her previous photographs suggested a disease duration of approximately 10 years, and her serum calcium (Ca) was normal during this period. A biochemical work up confirmed a combined growth hormone (GH-) and prolactin (PRL-) cosecreting tumor with a GH level of 92.03 ng/mL (normal 0-3.61), an insulin-like growth factor-1 (IGF-1) level of 1,498 ng/mL (59-225), and a PRL level of 223.3 ng/mL (2-17.4). Magnetic resonance imaging (MRI) of the pituitary showed a 1.9-cm macroadenoma. Her preoperative work up revealed new onset hypercalcemia with a corrected serum Ca level of 10.7 mg/dL (8.5-10.5), an ionized Ca level of 1.37 mmol/L (1.08-1.30), a parathyroid hormone (PTH) level of 13.0 pg/mL (10-60), and a high 1,25(OH)2D3 level of 72.6 pg/mL (15-60). She underwent resection of the pituitary adenoma with normalization of GH and PRL levels, and her IGF-1 level decreased to 304 ng/mL. Her serum Ca (9.3 mg/dL), ionized Ca(1.22) and 1,25(OH)2D3 levels (38.6 pg/mL) normalized after surgery.


CONCLUSIONS
While overt hypercalcemia in acromegaly is rare, it tends to occur late in the disease course. The hypercalcemia is mediated by elevated 1,25(OH)2D3 levels rather than PTH.
Department of Internal Medicine, Cleveland Clinic Foundation, Cleveland, Ohio.
Pooja
P
Manroa
Department of Endocrinology, Diabetes, and Metabolism, Cleveland Clinic Foundation, Cleveland, Ohio.
Subramanian
S
Kannan
Department of Endocrinology, Diabetes, and Metabolism, Cleveland Clinic Foundation, Cleveland, Ohio.
Betul
B
Hatipoglu
Department of Endocrinology, Diabetes, and Metabolism, Cleveland Clinic Foundation, Cleveland, Ohio.
Angelo
A
Licata