Immunoradiometric assay of human intact proinsulin applied to patients with type 2 diabetes, impaired glucose tolerance, and hyperandrogenism.
We describe an immunoradiometric assay for human intact proinsulin in serum. In this method, one monoclonal antibody, coated onto polyacrylamide beads, cross-reacts with proinsulins and insulin. A sandwich is formed with intact proinsulin, split (65-66) proinsulin, and des (64-65) proinsulin binding with an 125I-labeled monoclonal antibody specific for an epitope at the intact B-C junction of proinsulin. Because split (65-66) and des (64-65) proinsulin concentrations are very low in serum, this assay essentially measures intact proinsulin. When we used 1-mL serum samples, the mean detection limit was 0.4 pmol/L. Mean proinsulin concentrations (pmol/L) were 3.4 (range 1-9.1) in healthy fasting subjects, 28.5 (9.7-101) in patients with type 2 diabetes (treated with metformin and sulfonylureas), 5.0 (1.6-9.3) in women with hyperandrogenism and normal insulinemia, 10.3 (2.6-36) in women with hyperandrogenism and hyperinsulinemia, and 8.5 (4.8-21.3) in patients with impaired glucose tolerance.
Chevenne
D
D
Hôpital Robert Debré, Laboratoire de Biochimie-Hormonologie, Paris, France.
Ruiz
J
J
Lohmann
L
L
Laudat
A
A
Leblanc
H
H
Gray
I P
IP
Passa
P
P
Porquet
D
D
D000328:Adult; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D017588:Hyperandrogenism / Q000097:blood*; D015592:Immunoradiometric Assay / Q000379:methods* / Q000706:statistics & numerical data; D007328:Insulin / Q000097:blood; D008297:Male; D051379:Mice; D008863:Microspheres; D008875:Middle Aged; D011384:Proinsulin / Q000097:blood*; D012016:Reference Values; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D007328:Insulin; D011384:Proinsulin