DIMINISHED KIDNEY-FUNCTION AND NEPHROCALCINOSIS IN RATS FED A MAGNESIUM-DEFICIENT DIET

The effect of a magnesium-deficient diet on kidney function was studie d in young male rats. The rats were fed a purified diet with a magnesi um content of either 20.5 (control diet) or 2.6 mmol/kg (magnesium-def icient diet) for 21 d. In rats fed the magnesium-deficient diet, kidne y wet and dry weights were significantly increased, and calcium and ph osphorus concentrations in the kidney were significantly higher than i n rats fed the control diet. Upon histological examination, an increas e in the mesangial matrix of the glomeruli and injury to the brush bor der of the proximal tubules were observed in rats fed the magnesium-de ficient diet. Also, a deposition of calcium was observed in the tubule s of the corticomedullary junction and medulla of these rats. Total pr otein and albumin concentrations in serum were significantly decreased in rats fed the magnesium-deficient diet. Urinary albumin excretion w as significantly higher, and N-acetyl-beta-D-glucosaminidase activity in the urine was significantly increased in rats fed the magnesium-def icient diet. These findings indicate diminished glomerular and proxima l tubular functions. We suggest that a magnesium-deficient diet not on ly induces nephrocalcinosis, but it also diminishes kidney function.