The effect of Na₂SO₄ on urinary acidification in chronic renal disease

The effects of Na₂SO₄ on the pattern of urinary acid excretion were studied in 6 normal subjects and 14 patients with chronic renal disease when the serum bicarbonate concentration was normal and reduced. The infusion of Na₂SO₄ into patients with renal disease resulted in a rise in urine pH and bicarbonate excretion when the serum bicarbonate was normal. In contrast, normal subjects consistently excreted a more acid urine in response to Na₂S0₄. During metabolic acidosis, the infusion of Na₂SO₄ in the patients resulted in urinary acidification. These findings suggest that in renal failure nephron overperfusion will flood the distal tubule with NaHCO₃ and impair urinary acidification even when a potent acidifying salt such as Na₂SO₄ is given. The inability of Na₂O₄ to acidify the urine of the diseased kidney indicates that this is not an expression of intrinsic tubular damage and this is seen in the effects of metabolic acidosis when Na₂SO₄ is able to elicit maximum urinary acidification. The findings permit a tentative reconstruction of some of the factors responsible for the metabolic acidosis of renal failure.