ALTERAZIONI DEL TRASPORTO TUBULARE DELL’ACQUA E DEGLI ELETTROLITI DURANTE INFUSIONE SALINA NELLA GLOMERULOSCLEROSI FOCALE

Ten adult patients with histologically-proven (light and electron microscopy and IMF) focal glomercular sclerosis (FGS) were investigated. All patients had normal GFR and blood pressure value. Proteinuria ranged from 2 to 7 g/day without any biochemical or clinical evidence of nephrotic syndrome. After a preliminary investigation on electrolyte metabolism, all patients were loaded i.v. with 2,000 ml of isotonic saline over 3 hs under sustained water diuresis. Ten normal subjects underwent the same investigation. Urine output absolute and fractional Na+ excretion, Cosm and CH2O were significantly lower in patients with FGS than in controls, whereas fractional excretion of K+ was significantly higher in kidney patients. Fractional excretion of Ca++ either in absolute value or referred to Na+ excretion, was significantly reduced in patients with FGS. These results suggest that tubular handling of Na+ and K+ may be affected in patients with FGS even in the absence of the nephrotic syndrome, as a consequence of hemodynamic and hormonal changes (hyperaldosteronism). The reduced urinary calcium excretion may be mainly regarded as a consequence of early hyperparathyroidism secondary to an acquired deficiency of the active metabolite of vitamin D, peculiar to protein-losing kidney disease. Yet, plasma values of parathormone were slightly increased in our patients.