Renal excretion of magnesium in chronic renal failure.

In 42 patients with chronic renal insufficiency the 24-hour magnesium excretion decreased with the progress of renal failure and was independent of the total and intrafiltrable magnesium concentration in the plasma. At the same time the fractional excretion of this ion increased progressively probably as a result of increased osmotic load acting on individual nephrons and/or the action of the natriuretic factor. The high correlation between fractional excretion of magnesium and sodium, and magnesium and calcium may suggest an interrelationship between the transport mechanisms of these ions in the nephron.