OBJECTIVES: Insulin-like growth factor-I (IGF-I) secretion is growth hormone (GH) dependent. However the data on using IGF-I assessment as a screening procedure in diagnosing GH deficiency are not consistent. The goal of the study was an analysis of the relations between GH secretion in stimulating tests and plasma IGF-I concentration.
PATIENTS & METHODS: The analysis comprised 540 children with short stature in whom two standard GH stimulating tests (GHST) were performed, together with an assessment of plasma IGF-I concentration. The relationships between GH peak in both tests and IGF-I secretion were analysed.
RESULTS: There was no correlation either between GH peaks in different tests or between GH and IGF-I secretion in particular patients. Moreover, both the mean IGF-I concentration was similar in the patients with normal and subnormal results of GHST and the mean GH peak in GHST presented similar in the groups of children with normal and decreased IGF-I secretion.
CONCLUSIONS: Assessment of IGF-I secretion fails to be a screening procedure for the results of GHST. The lack of correlation between the results of two GHST should be taken into account when evaluating the significance of GHST and IGF-I assessment in diagnosing GH deficiency.