IGF-I, IGFBP-3 and ALS generation test in Turner syndrome

Abstract

Objectives The pathophysiology of the short stature in girls with Turner syndrome (TS) is not well understood. The “IGF-I generation test” is used to assess the sensitivity to growth hormone. We compared the biochemical response to four days of growth hormone of TS and controls. Study design Pre-pubertal TS were recruited to participate in the study. Their siblings served as controls. IGF-I, IGFBP-3 and ALS were measured before and 5 days after using hGH (0.05 mg/kg/day). Student- t test was used to compare the differences in their responses. Results Eleven TS (mean age of 8.5 ± 2.4) and 11 siblings (6 females and 5 males) (mean age of 7.0 ± 2.0) participated in the study. The basal serum levels of IGF-I, IGFBP-3 and ALS were normal and not different between groups ( p = 0.62 for IGF-I, p = 0.91 for IGFBP-3 and p = 0.51 for ALS). The IGF-I generation test was positive in all controls and in 10/11 TS. The IGFBP-3 generation test was positive in 6/11 controls and 4/11 TS. After hGH the mean IGFBP-3 was lower in TS than in controls ( p = 0.08). The ALS response to hGH was not uniform between groups. Conclusions The IGF-I and ALS generation test results were not different between controls and TS. The IGFBP-3 results were higher in the control group but more than 50% of tested children did not pass. The IGF-I/IGFBP-3 generation tests, as presently done, did not help in the understanding of the short stature in TS. The use of different GH dosages and number of doses need to be investigated.