Normal plasma levels of IGF binding protein in Perthes' disease. Follow-up of previous report.

Plasma levels of insulin-like growth factor binding protein-3 (IGFBP-3) were measured in 55 children with Perthes' disease and 55 age- and sex-matched controls. IGFBP-3 values did not differ between the 2 groups and corresponded well to normal values found by others. The IGF I/IGFBP-3 ratio was reduced during the first 2 years of Perthes' disease. Our findings indicate that low levels of circulating IGF I in Perthes' disease, as we have reported previously, are caused neither by altered concentrations of the principal IGF-binding protein, IGFBP-3, nor by an underlying growth hormone deficiency.