Raised somatomedin activity in the serum of young boys with Perthes' disease revealed by bioassay. A disease of growth transition?

This paper reports a study of the serum somatomedin activity in 67 boys with Perthes' disease and in 43 control boys aged three to 11 years. It was undertaken to evaluate some abnormalities of growth in children with Perthes' disease that have been previously reported. A brief account is given of knowledge relating to somatomedins in postnatal and fetal life. Serum somatomedin activity was measured using a bioassay based on the principle that somatomedins stimulate the synthesis of both DNA and proteoglycans in porcine costal cartilage. In control boys, the serum somatomedin activity increased with age, which is consistent with previous reports for normal children. In affected boys, the normal increase in serum somatomedin activity with age did not occur. The somatomedin activity in affected boys is higher than in control boys at three to five years but not at six to 11 years of age. Findings support the hypothesis that some children with Perthes' disease have an abnormality of the growth hormone-dependent somatomedins. The serum findings together with those of both skeletal age delay and impaired skeletal growth distally in the limbs are consistent with the view that the general disorder of some children with Perthes' disease results from an imbalance in mechanisms that determine the postnatal transition from the "fetal" to the "basic" component of the normal human growth curve.