Interní Med. 2011; 13(7): 314-317

Hypercalcemia - differential diagnosis and available medical therapy

prof.MUDr.Petr Broulík, DrSc.

III. interní klinika 1. LF UK Praha

Normal level of calcium for many physiological processes in the body is extremely important and under normal circumstances, it is remarkably

constant between 2.2 to 2.6 mmol/l. Approximately half of the total calcium in serum is bound to proteins, primarily albumin.

Hypercalcemia arises when the entry of calcium into the blood is greater than its loss. This occurs when excessive bone resorption, excessive

resorption of calcium from the gastrointestinal tract, and abnormal calcium binding to proteins leading to increased levels of calcium in the

blood that exceed the capacity of the kidneys to remove calcium in the urine. Constant level of calcium is controled by three calcitrophic

hormones, parathyroid hormone (PTH), active metabolite of vitamin D (calcitriol) and calcitonin. The clinical picture of hypercalcemia varies

from mild asymptomatic with just biochemical abnormalities determined by routine biochemical testing, to life-threatening hypercalcemia

requiring treatment in intensive care unit. The two most common causes of hypercalcemia are PHPT and cancer. PHPT is a disease caused

by increased production of PTH by adenoma of one or more of the parathyroid glands (85 %) or parathyroid hyperplasia (11 %). Hypercalcaemia

caused by tumors occurs in up to 30 % of patients with cancer. It is usually the result of increased bone resorption in patients

with bone metastases. Three main mechanisms leading to hypercalcemia are PTHrP (parathyroid hormone like peptide), local factors and

calcitriol. To a group of hypercalcemia caused by PTH beside PHPT belong chronic administration of lithium with an enlarged parathyroid

glands, tertiary hyperparathyroidism in chronic secondary hyperparathyroidism and ectopic production of PTH. Treatment depends on

the severity of hypercalcemia and the clinical picture. Most of therapeutic mechanisms is tending to decrease the resorption of calcium

from bone, increased calciuria and decrease gut absorption of calcium. In patients with PHPT and hypercalcemia is the drug of first choice

parathyroidektomie. Calciomimetics are substances that act on calcium sensing receptors in cells of the parathyroid glands and can be

successful in the treatment of PHPT. Hypercalcemia induced by excessive osteolytic resorption is sucessfully treated with bisphosphonates

which should be administered intravenously in saline.

Keywords: primary hyperparathyroidism, tumor induced hypercalcemia, diferential diagnosis of hypercalcemia, therapy

Published: October 1, 2011  Show citation