Abstract
Hypercalcemia is a frequent electrolyte disturbance, which is most commonly caused by cancer and parathyroid hormone (PTH) disturbances. The mechanisms by which cancer produces hypercalcemia are: direct bone involvement and the production of substances that may accelerate bone resorption. In addition to PTH-like material, 2 such substances are prostaglandins and the so-called osteoclast activating factor, which is a material isolated from malignant cell lines, particularly lymphomas and multiple myeloma. Besides the particular manifestations of the underlying disease, the clinical consequences [humans] of hypercalcemia are the same regardless of the origin.