Association Of Pharmacological Tests And Study Of 24-Hour Growth-Hormone Secretion In The Investigation Of Growth-Retardation In Children - Analysis Of 257 Cases

Growth hormone (GH) secretion can presently be investigated by several methods: pharmacological provocative tests, study of 24-h GH secretion, measurement of somatomedin-C (Sm-C)/insulin-like growth factor (IGF) I and the growth hormone-releasing hormone (GHRH) test. In order to compare the results obtained, these methods were used in 257 children with growth retardation (169 boys, 88 girls). Their height SD was -2.7 +/- 0.2, chronological age 11 3/12 +/- 1 6/12 years, and bone age 8 4/12 +/- 1 4/12 years. Mean growth velocity was 4.5 +/-1.5 cm/year. One hundred and thirty-eight boys and 80 girls were prepubertal, and 31 boys and 8 girls were pubertal (B2 G2). All children underwent the study of 24-h GH secretion (n = 257) and pharmacological provocative tests (two tests, n = 213; one test n = 44). Sm-C/IGF I was measured in prepubertal children (n = 13 1), and a GHRH test was carried out (n = 153). In addition, the mean integrated concentration of growth hormone secretion (IC-GH) was assessed in a control group of 23 children and was found to be 5.4 +/- 1.2 ng/ml/min. The IC-GH in the group as a whole was 2.6 ng/ml/min. The mean maximum peak during pharmacological tests varied considerably according to the test used, ranging from 7.8 ng/ml for the arginine test to 17.1 ng/ml for the glucagon and betaxolol test. The maximum peak and the 24-h IC-GH were not significantly correlated. Moreover, conflicting results were found in the various groups which were defined by the values of the maximum peak during pharmacological tests and by their IC-GH levels. In view of these results, it would seem preferable to use the different methods of investigation in association, rather than to compare them. When these methods are associated, the following types of GH deficiencies can be identified: concordant or double deficiencies, with low responses to tests and low IC-GH (severe GH deficiencies and some partial and dissociated GH deficiencies); discordant or single GH deficiencies, with either low 24-h secretion (children with neurosecretory dysfunction or poor endogenous secretion) or low responses to pharmacological tests (poor pharmacological responders); and lastly, a group of short children who nevertheless have normal responses to pharmacological tests and normal 24-h GH secretion.