9 - Disorders of calcium homeostasis

Abstract

This chapter focuses on disorders of calcium homeostasis. The normal steady-state regulation of calcium includes diet, physiochemical mechanisms and hormones. In addition to the requirements for the maintenance of the skeleton, there is the over-riding need to maintain a constant concentration of ionized calcium, which is essential for normal neuromuscular function and probably for other cell functions. Disturbances in diet, physiochemical mechanisms, and hormones control systems are associated with disorders of calcium homeostasis. The latter are usually manifested as either hypercalcemia or hypocalcaemia. The symptoms because of hypercalcemia are vague, nonspecific and the same irrespective of the causative mechanism. The symptoms and signs are proportional to the degree of elevation in the serum calcium concentration and offer no clue to the etiological mechanism. In many patients, the differential diagnosis of hypercalcaemia is based on evaluation of their biochemical criteria. The differentiation of the biochemical findings must be related to the mechanisms that cause the increases in plasma calcium concentration. The other disorder of calcium homeostasis is hypocalcemia, which involves tetany with carpopedal spasms in adults or laryngeal spasm in infants; some patients. Psychiatric symptoms may occur, the most common of which are anxiety and depression. Chronic hypocalcemia may be associated with progressive intellectual loss and cataract.