Renal excretion of magnesium in patients with hydronephrosis (author's transl)

Abstract

Magnesium concentration in serum was significantly lower in patients with bilateral hydronephrosis (1.52±0.15mEq/l, mean±S. D.) than in 74 healthy adults (1.82±0.17mEq/l) and 10 normal control subjects (1.65±0.15mEq/l) (p<0.05). There was no correlation between serum magnesium concentration and GFR.In regard to magnesium clearance (CMg) under water diuresis there existed no significant difference between patients with bilateral hydronepherosis and normal control subjects. No significant reduction of CMg was observed in hydronephrotic patients with lowered GFR.Excretion fraction of filtered magnesium (EFMg) in patients with bilateral hydronephrosis (13.58±9.76%) was significantly higher than that of normal control subjects (4.54±1.75%) (p<0.01), and tended to be higher as GFR became lower.Between EFMg and excretion fraction of filtered sodium (EFNa) in patients with bilateral hydronephrosis, a high correlation was noted: the regression line being EFMg=2.52×EFNa±2.61 (γ=0.786, p<0.01). Whereas no correlation was seen between EFMg and excretion fraction of filtered calcium.In 4 patients with unilateral hydronephrosis who underwent individual renal function test, EFMg of the lydronephrotic kidney was higher than that of the contralateral normal kidney. On the other hand, in 3 patients with unilateral renal arterial stenosis, EFMg of the stenotic kidney was lower than that of the normal kidney on the opposite side.EFMg observed in 4 patients with primary aldosteronism and in 3 patients with primary hyper-parathyroidism showed no significant difference from that of normal control subjects.EFMg estimated in 4 patients with unilateral hydronephrosis during infusion of Mg-aspartate and furosemide demonstrated a very sharp increase in both hydronephrotic and normal kidneys, and the difference between the two kidneys was reduced.The above-mentioned results indicate that there it a tendency of renal wasting of magnesium in hydronephrosis probably due to disturbances in magnesium reabsorption in the renal tubules.