Insulin-like growth factor-binding protein-6 levels are elevated in serum of children with chronic renal failure: a report of the Southwest Pediatric Nephrology Study Group.

Previous studies suggest that growth retardation in children with chronic renal failure (CRF) results in part from inhibition of insulin-like growth factor (IGF) action by excess serum IGF-binding proteins (IGFBPs). Excess IGFBPs in CRF serum include IGFBP-1, -2, and -3 and a diffuse ∼24- to 28-kDa IGFBP band identified by[ 125I]IGF ligand blot. The present studies characterized this diffuse ∼24- to 28-kDa band. Initial studies identified this band as IGFBP-6, because it was immunoprecipitated by antiserum raised against a synthetic peptide of human IGFBP-6 (hIGFBP-6). Additional[ 125I]IGF ligand blots found that the immunoprecipitated band was 1) recognized by [125I]IGF-II but not[ 125I]IGF-I, 2) more abundant in CRF than in normal serum, and 3) more abundant in serum from dialyzed than nondialyzed prepubertal CRF children. Using the hIGFBP-6 antiserum in a specific and sensitive RIA, we found that serum IGFBP-6 levels were 4.7 ± 1.7 nmol/L in 10 normal prepubertal children, 21.4 ± 6.1 nmol/L in 44 nondi...