Low-molecular-mass proteinuria as a marker of proximal renal tubular dysfunction in normo- and microalbuminuric non-insulin-dependent diabetic subjects.
We determined the urinary excretion, expressed as the protein/creatinine ratio (morning urines), of albumin (a marker of glomerular dysfunction) and retinol-binding protein (RBP; a low-molecular-mass protein marker of tubular proteinuria) in 102 non-insulin-dependent diabetic patients. There was a statistically significant (P < 0.0001) correlation (rho = 0.38) between the urinary excretion values of the two proteins. The population could be divided into four subgroups: 32 with normal excretion values, 15 with above-normal urinary excretion of RBP, 24 with above-normal urinary excretion of albumin, and 31 patients with above-normal urinary excretion of both proteins. No patients had above-normal serum creatinine concentrations or above-normal serum RBP concentrations. This seems to exclude "tubular overflow proteinuria" as the cause of the increased urinary excretion of RBP seen in some patients with non-insulin-dependent diabetes. Our data suggest the presence of a state of proximal tubular dysfunction in these patients.
Holm
J
J
Department of Clinical Chemistry, Central Hospital Nykøbing Falster, Denmark.
Hemmingsen
L
L
Nielsen
N V
NV
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000419:Albuminuria / Q000378:metabolism*; D003404:Creatinine / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000652:urine*; D004797:Enzyme-Linked Immunosorbent Assay; D005198:Fanconi Syndrome / Q000150:complications / Q000652:urine*; D006801:Humans; D008875:Middle Aged; D012177:Retinol-Binding Proteins / Q000652:urine*
D012177:Retinol-Binding Proteins; D003404:Creatinine