Low plasma levels of insulin-like growth factor I in Perthes' disease. A controlled study of 59 consecutive children.

We studied Insulin-like Growth Factor I (IGF I) plasma levels, standing height, and weight in 59 consecutive children with Perthes' disease and 59 matched controls. The plasma-IGF I levels, measured by radioimmunoassay after acid ethanol extraction, were reduced in affected children during the first 2 years after the diagnosis of Perthes' disease. Partially paralleling the alterations in IGF I plasma levels, there was a tendency towards growth arrest and impaired weight-gain during early-stage disease, followed by catch-up growth and increased weight-gain. No relation was found between degree of femoral head involvement, according to Catterall (1971), and IGF I plasma-levels or body mass. Our data may reflect an impaired synthesis or release of IGF I relative to age in Perthes' disease, or changes in the affinity or metabolism of IGF binding proteins. The observed changes seem to be of a temporary nature.