Increased urinary beta-thromboglobulin excretion in diabetes assayed with a modified RIA kit-technique

A modification of the commercial radioimmunoassay (RIA) kit adapting to the assay of beta-thromboglobulin (beta-TG) in the urine, is described. The urine was concentrated by dialysis against dry Sepharose G 200. 131I-albumin was used as marker. Experiments in which 125I-beta-TG and 131I-albumin were added simultaneously showed a parallel recovery of both markers in the final sample. The sensitivity of the RIA was enhanced by incubation overnight of the urine sample with the antiserum. Increased urinary beta TG values were found in 20 patients with diabetes mellitus as compared to 20 young healthy normals. Increased urinary beta-TG values correlated with decreased creatinine clearance, but the difference between diabetics and normals was still observed when patients with a creatinine clearance of less than 100 ml/min were excluded. The urine beta TG level was correlated with the presence of neovascularization within the diabetic group.