Usefulness of the measurement of insulin-like growth factor 1 (IGF-I) and IGF-1 binding protein-3 (IGFBP-3) for the diagnosis of growth hormone (GH) deficiency in children

Background: The diagnosis of GH deficiency (GHD) is based upon the results of GH stimulation tests, which have several drawbacks. Aim: To evaluate the usefulness of IGF-1 and IGFBP-3 for the diagnosis of GHD in prepuberal chi ldren. Material and methods: We measured IGF-1 and IGFBP-3 in three group o f subjects: I. GHD (n:24), height <-2SD for age (Z score, average +/- SD: - 4.2 +/- 1.2), growth velocity <p10 (3.4 +/- 1,0 cm/year) and peak GH level on two GH stimulation tests <7 ng/ml (1.2 +/- 0.6 ng/ml); II. Short non-GHD (NGHD, n:32), height of - 2.7 +/- 0.9 SD for age, growth velocity <p 25 (3 .9 +/- 1.2 cm/year), and peak GH level on two GH stimulation tests >7 ng/ml (15.3 +/- 6.9 ng/ml), y III. Normal school children (n:35) with normal hei ghts (-0.17 +/- 0.12 SD) were studied as controls. Results: IGF-1 and IGFBP -3 were significantly lower in GHD than in NGHD and controls (p <0.001), an d in NGHD than in C (p <0.001). We defined the normal range of both protein s as +/- 2 SD of the mean of the control group. Using this criteria, IGF-I was low in 21/24 GHD, and in 12/32 NGHD. IGFBP-3 was low in 22/24 GHD, and ill 6/32 NGHD. Only 2 GHD patient had both exams ill the normal range, sugg esting that he is probably NGHD. 4/32 of the NGHD had both exams below norm al range, suggesting that they are probably GHD. Conclusions: IGF-1 and IGF BP-3 are important tools for the diagnosis of GHD.