Insulin-like growth factor I, IGF binding protein 3, and IGFBP protease activity: relation to anthropometric indices in solid tumours or leukaemia

Objectives-To measure the serum concentrations of insulin-like growth facto r I (IGF-I) and IGF binding protein 3 (IGFBP-3), and the level of IGFBP-3 p rotease activity in 38 children presenting with malignancies, and to assess their relation with auxological parameters and nutritional status. Methods-Height, weight, skinfold thickness, and mid-upper arm circumference (MUAC) were recorded using standard techniques. IGF-I and IGFBP-3 were mea sured using specific radioimmunoassays. Serum IGFBPs were also visualised o n western ligand blot. IGFBP-3 protease activity was assessed by the extent of fragmentation of recombinant [I-125]-IGFBP-3, compared with that induce d by pregnancy serum. Anthropometric and radioimmunoassay data were express ed as standard deviation scores (SDS). Results-The median (range) IGF-I SDS was significantly reduced in all patie nts (-1.1 (-5.1 to 1.2)) and lower in children who were malnourished (-2.5 (-3.9 to 0.1)). IGFBP-3 SDS was within the normal range for 31 of 38 patien ts but IGFBP-3 protease activity was raised in all patients. Neither IGFBP- 3 concentration nor protease activity was affected by nutritional status. I GF-I correlated with MUAC (r = 0.41) and subscapular skinfold thickness SDS (r = 0.38),but not with weight, height, weight for height, or triceps skin fold thickness. Conclusions-IGF-I is low in children with malignancies, and even lower in t hose who are malnourished. IGFBP-3 concentrations were normal in most patie nts but interpretation is complicated by the presence of raised IGFBP-3 pro tease activity, which could lead to overestimating concentrations of intact peptide. IGF-I appears to relate to arm anthropometry as an index of nutri tional status but not height, weight, or weight for height, as would be exp ected in normal children.