Quantitative enzymuria following aorto-renal angiography.

Quantitative estimation of urinary enzymes has been advocated as a more sensitive marker than conventional renal function tests to assess radio-contrast media induced nephrotoxicity. We studied 27 subjects with normal renal functions who underwent abdominal aortography for varied indications. Among these, 8 also required selective renal arteriography and 3 underwent arch aortography in addition. Sodium iothalamate was used as a radio-contrast medium and the average amount injected was 73 ml (45 to 120 ml) per subject. Standard renal function assessment including urinalysis, 24 hour urinary protein excretion, creatinine clearance done both before and after aortography did not show any significant alteration. Urinary excretion of tubular enzymes including leucine aminopeptidase (LAP), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT) and maltase (MAL) was estimated before and 2, 24 and 48 hours after aortography. All enzymes showed a significant rise at 2 hours. Urinary excretion of LAP, ALP and GGT peaked at 24 hours after aortography without a further change in MAL levels. Enzymuria returned to baseline values 48 hours following the procedure. It is concluded that an increase in the urinary excretion of the brush-border enzymes within 24 hours of contrast media administration may suggest an early nephrotoxicity.

Nephrotoxicity of human Bence Jones protein in rats: proteinuria and enzymuria profile

The effect of intravenous administration of 80 mg purified human Bence Jones protein twice weekly for 5 weeks was investigated in male Wistar rats (N = 7; 2 months old). A state of immunological tolerance was demonstrated by the absence of a B-cell response (plaque-forming cells and hemagglutination titers) and by the absence of detectable antigen or antibody deposition in glomeruli, as indicated by light and electron microscopy. No rise in blood urea level was detected (33.9 +/- 4.3 vs 32.8 +/- 1.3 mg per cent ). There was an increase in proteinuria (5.3 +/- 0.9 vs 32.8 +/- 4.0 mg/day), mainly due to Bence Jones protein excretion (0 vs 29.2 +/- 5.2 mg/day), with a slight but significant increase in albuminuria (0.2 +/- 0.1 vs 1.0 +/- 0.2 mg/day). There was a significant increase of lysosomal N-acetyl-beta-D-glucosaminidase in the urine (6.1 +/- 1.3 vs 72.7 +/- 18.8 mU/mg in creatinine). Lysosomal accumulation of Bence Jones protein in proximal tubular cells was evidenced by immunoelectronmicroscopy with protein A-gold. These results clearly showed proximal tubular dysfunction induced by chronic Bence Jones protein administration, without interference of autologous immune response as demonstrated by immunological state of tolerance