Knowledge of the metabolism of calcium and phosphorus is of considerable importance to the internist. An understanding of the metabolic turnover of these ions is necessary in the consideration of bone diseases. Abnormalities of calcium and phosphorus metabolism are common in acute and chronic renal failure. Disturbances in neuromuscular function are frequently related to alterations in the concentration of ionized calcium in the extracellular fluid. Phosphorus is an important intracellular anion, which enters into numerous biochemical reactions.
Alterations in calcium and phosphorus metabolism are often reflected in abnormalities of urinary excretion. It is pertinent, therefore, to examine the renal mechanisms concerned with the excretion of these ions. Although the metabolism of calcium and phosphorus are commonly considered together, it will be more convenient to examine the renal excretion of these substances separately, as the mechanisms involved are very different.
Renal Excretion of Phosphorus
Normally most of the phosphorus lost from