[Contribution of the IGF (insulin-like growth factors or somatomedins) competitive binding assay in the study of growth disorders in children (results for 124 observations) (author's transl)].

A competitive binding assay for IGF (insulin-like growth factors) employing a specific carrier protein produced by rat liver in culture has been used in a study of a variety of growth disorders in children. In 34 subjects with a total somatotropic deficiency, serum IGF levels were significantly (p < 0.001) lower than those in normal children for whom the means were 0.57 +/- 0.05 (SEM) U/ml between the ages of 1 and 5, and 1.01 +/- 0.11 U/ml between the ages of 5 and 15. Within this group of patients, there was also a significant difference in IGF levels depending on whether the deficiency was idiopathic (0.16 +/- 0.03 U/ml) or caused by a tumour (0.49 +/- 0.06 U/ml). IGF levels were particularly low in 2 cases of Laron's syndrome (0.08 and 0.03 U/ml) and 6 cases of coeliac disease (0.19-0.27 U/ml). In the later group, a gluten-free diet resulted in a rise in IGF levels. However, the stunted growth observed in 10 cases of Cushing's syndrome was found to be independent of IGF levels which fell within the normal range (1.02 +/- 0.11 U/ml). For 34 children investigated because of idiopathic retarded growth varying from --2 to --4 SD, the mean IGF levels (0.68 +/- 0.04 U/ml) were significantly lower than controls (p < 0.001). By contrast, abnormally high IGF levels were found in children with tall stature (> 3 SD). In 7 children aged between 1 and 5, the mean was 0.94 +/- 0.05 U/ml and in 17 older patients, 1.47 +/- 0.11 U/ml, with some cases reaching levels similar to those of untreated acromegalics. In both age groups the means were significantly higher than control levels (p < 0.001). Oestrogen treatment led to a progressive drop in IGF levels accompanied by slower growth, and normal levels were reached by the time ossification was established.