ABSTRACT
Disorders of calcium metabolism are common in clinical practice and may result in hypocalcaemia or hypercalcaemia as well as bone abnormalities. Intimately associated with calcium disorders are disorders involving phosphate and magnesium metabolism. Faecal calcium is derived from the diet and that portion of the large amount of intestinal secretions that has not been reabsorbed. Calcium in the intestine may form insoluble, poorly absorbed complexes with oxalate, phosphate or fatty acids. The consequences of most disturbances of calcium metabolism can be predicted from knowledge of the actions of Parathyroid hormone on bone and on renal tubular cells, and from plasma concentrations of calcium and phosphate. Treatment of the metabolic acidosis with bicarbonate is usually contraindicated because a rise in blood pH may cause precipitation of calcium phosphate in extraosseous sites. Without an adequate supply of calcium and phosphate, osteoid cannot be calcified despite marked osteoblastic proliferation.
