The interrelationship between sodium, calcium, and magnesium excretion in advanced renal failure.

Abstract

Abstract The renal excretion and the interrelationships between the fractional excretion of sodium, calcium, and magnesium were evaluated in 50 patients with advanced renal failure. Hypocalciuria was found in 46 patients and hypomagnesuria in 35. The fractional excretions of sodium, calcium, and magnesium were high and equaled (mean ± S.D.) 0.09 ± 0.08, 0.09 ± 0.08, 0.37 ± 0.19, respectively. The relationship between the fractional excretion of sodium and calcium followed a regression slope of one and that between sodium and magnesium of 1.8. These relationships resembled those seen in experimental animals undergoing extracellular volume expansion by saline infusion. The infusion of calcium chloride caused an increase in the excretion of all 3 ions. Calcium infusion did not alter significantly the relation between the fractional excretion of sodium and calcium. The data are consistent with the concept that a common mechanism(s) underlies the high fractional excretion of all 3 ions observed in advanced renal failure.