Urinary excretion of the carboxy terminal domain of type IV collagen is associated with kidney size and function in IDDM

We evaluated whether urinary excretion of the carboxy terminal domain (NC1) of Type IV collagen is associated with glomerular filtration rate and kidney size in Type I (insulin-dependent) diabetes mellitus (IDDM). Urinary excretion rate of NC1, glomerular filtration rate (GFR), and kidney size were measured in 16 men with Type I diabetes. Their mean age was 33.3 ± 6.1 years with a duration of diabetes of 14.9 ± 3.7 years (mean ± SD). The urinary excretion rate of NC1 was higher in the diabetic patients than in 18 healthy control subjects. Urinary excretion of NC1 was associated with both kidney size, parenchymal width, and GFR (r = 0.73, p = 0.001; r = 0.63, p = 0.009; r = 0.53, p = 0.04, respectively). The exact relationship between these factors and basement membrane turnover/synthesis remains to be elucidated.