Citrate metabolism and the mechanism of renal calcification induced by magnesium depletion

Abstract

The effects of magnesium deficiency in rats on serum, bone, and urine citrate concentrations and the influence of concurrent vitamin D depletion were studied. Our findings are in agreement with the concept that a fall in serum magnesium stimulates parathyroid hormone output. Elevated serum calcium and citric acid levels, hypocalciuria, hypophosphatemia and hyperphosphaturia were found consistently in magnesium-deficient rats. The development of hypercalcemia and hypercitricemia was prevented by vitamin D deficiency which is in accord with the data indicating that full expression of parathyroid hormone activity does not occur in the absence of vitamin D. Citrate excretion was reduced in the magnesium-deficient rats. Whatever the mechanism involved in the reduction of urinary citrate by magnesium deficiency the sequence of events favors the precipitation of calcium phosphate in the renal tubules in a manner resembling that seen in acetazolamide administration. 13 Kidney calcinosis was prevented by vitamin D deficiency, by reduction of phosphorus excretion or by increasing urine citrate concentrations. Magnesium deficiency is an additional example of the association of hypocitricuria and nephrocalcinosis.