Hypercalcemia of Malignancy

Abstract

Hypercalcemia is frequently associated with malignant disease (Stewart et al, 1980, Mundy et al, 1984). The primary underlying cause is an increase in osteoclastic bone resorption but the mechanisms which lead to this increase are still the focus of current research. A number of investigators have utilized different approaches to identify factors which are secreted from tumors associated with hypercalcemia and which are responsible for increased bone resorption. It is now apparent that different classes of protein factors are responsible for the hypercalcemia observed in different types of malignancies. For example, in patients with myeloma the lymphokine, osteoclast-activating factor, is most likely the humoral factor secreted from myeloma cells and causing bone resorption (Mundy et al, 1974). Hypercalcemia can also occur in patients who have solid tumors without bone metastases and bone resorption in this type of hypercalcemia is often associated with hypophosphatemia and an increase in nephrogenous cyclic AMP excretion (Stewart et al, 1980).