Radioimmunoassay of growth hormone-dependent insulinlike growth factor binding protein in human plasma.
A specific radioimmunoassay has been established for a growth hormone-dependent insulinlike growth factor (IGF) binding protein (BP) from human plasma. Although the assay was directed against a 53-kD, acid-stable BP subunit, the main immunoreactive BP in the circulation had an apparent molecular mass of approximately 125 kD. Only higher primate species showed cross-reactivity, and IGF-I, IGF-II, and other peptides were without effect. Circulating BP levels in healthy subjects rose threefold from early childhood to puberty. In 65 adults aged 18 to 65, the mean level (+/- SD) was 6.12 +/- 1.43 micrograms/ml, and declined with age. Strong growth hormone-dependence of BP was also seen; there was a 2.2-fold increase in active acromegaly and a 50-80% reduction in growth hormone deficiency. Poorly controlled diabetic subjects had BP levels 40% below normal, whereas in renal failure and third-term pregnancy a mild elevation was seen. Measurement of BP may provide a useful adjunct to IGF assays in growth disorders.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000653:Amniotic Fluid / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis* / Q000276:immunology; D002352:Carrier Proteins / Q000032:analysis* / Q000097:blood* / Q000276:immunology; D003429:Cross Reactions; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018969:Insulin-Like Growth Factor Binding Proteins; D007674:Kidney Diseases / Q000097:blood; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011863:Radioimmunoassay; D013002:Somatomedins / Q000378:metabolism*
D001798:Blood Proteins; D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins; D013006:Growth Hormone