Evaluation of IGF-I Levels in Subjects whose GH Secretion Status was Judged Mainly by Auxological Data

Abstract

Serum IGF-I levels are one of the important clinical parameters in the evaluation of GH secretion. Almost all previous reports on the clinical utility of serum IGF-I levels in the evaluation of GH secretion have been based on the comparison between IGF-I levels and GH peaks of the GH provocation test. GH provocation tests have limitations such as a relative lack of normal values. There has been no report on serum IGF-I levels in short children whose heights were monitored over a range of years and whose diagnosis was made not based on GH peaks of the GH provocation test. The purpose of this study was to evaluate the clinical utility of IGF-I levels based on clinical and auxological data without using GH peaks of the GH provocation test. Here, 125 subjects with short stature were seen at least twice for more than a year from 1985 to 2000 at our hospital. Four populations were selected from the 125 subjects without using GH peaks of the GH provocation tests. The first group (CGHD, N=15), complete GH deficiency, consisted of prepubertal patients with growth velocity less than -1.5 SD, invisible/thin stalk on MRI or CNS lesion such as brain tumor. The second group (HV-N, N=22), subjects of prepubertal and growing children with short stature (Ht < -2 SD), had normal height velocity for at least one year (height velocity > +0 SD). The third group (FH-N, N=8) subjects had short height (Ht < -2 SD) in childhood but normal final height (Ht > -2 SD). The fourth group subjects were prepubertal short children (Ht < -2 SD) with a decrease in height velocity (HV-D, N=10) who were diagnosed as familial short stature (FSS) or constitutional delay of growth and adolescence (CDGA). Measurements of serum IGF-I levels were carried out from the age of three to nine years in females, three to ten years in males in CGHD, HV-N and HV-D, and before reaching final height in FH-N. IGF-I levels of 13 out of 15 CGHD were low values under the cut-off line (< -2 SD). IGFBP-3 levels of CGHD were all low values under the cut-off line (< -2 SD). IGF-I levels of HV-N, FH-N and HV-D were all within the normal range (> -2 SD), except for one subject in group HV-D. In conclusion, IGF-I measurements are useful for screening patients who need GH treatment and probably for diagnosing GHD. Additional IGFBP-3 measurements are valuable in diagnosing GHD especially at the age of less than five years.