Determination of urinary lysozyme for potential detection of tubular dysfunction in diabetic nephropathy.
Seeking to study whether measurement of lysozyme (EC 3.2.1.17) in urine by a reliable radioimmunoassay can provide a suitable index of renal tubular function and how lysozymuria develops in temporal relation to proteinuria in diabetic nephropathy, we have compared the urinary excretion of lysozyme and beta 2-microglobulin with the 15-min excretion rate of phenolsulfonphthalein in 39 patients with Type 2 (non-insulin-dependent) diabetes and investigated the temporal relation between the onset of lysozymuria and proteinuria in 15 patients with Type 1 (insulin-dependent) diabetes. The concentrations of lysozyme and beta 2-microglobulin in urine increased in proportion to the decrease in the rate of excretion of phenolsulfonphthalein in these patients. The coefficient of correlation between lysozyme concentration and the 15-min excretion rate of phenolsulfonphthalein (r = -0.70) was higher than that between beta 2-microglobulin concentration and the 15-min excretion rate of phenolsulfonphthalein (r = -0.46). Abnormally high lysozymuria, suggesting the existence of tubular dysfunction, was demonstrated in six of the patients with Type 1 diabetes who showed no proteinuria or only a slight increase in urinary protein excretion. Lysozymuria may thus be added to a list of the indicators for diabetic nephropathy.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology; D003928:Diabetic Nephropathies / Q000201:enzymology* / Q000503:physiopathology; D006801:Humans; D007684:Kidney Tubules / Q000503:physiopathology*; D008875:Middle Aged; D009113:Muramidase / Q000097:blood*; D010637:Phenolsulfonphthalein; D011507:Proteinuria / Q000201:enzymology; D001613:beta 2-Microglobulin / Q000652:urine
D001613:beta 2-Microglobulin; D009113:Muramidase; D010637:Phenolsulfonphthalein