Insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) concentrations compared to stimulated growth hormone (GH) in the evaluation of children treated for malignancy

Objective: The aim of this investigation was to evaluate the utility of IGF -I and IGFBP-3 determinations in screening for GH deficiency (GHD) in child ren previously submitted to treatment for childhood malignancy, Patients and methods: We compared the GH responses to two pharmacological t ests (arginine and levo-dopa) with the IGF-I and IGFBP-3 levels in 48 patie nts (29 boys) who had undergone bone marrow transplantation (BMT) (36 patie nts) or treatment for a solid cranial tumor (12 patients). Results: 22 patients (45.8%) showed GHD (i.e. GH peak <8 ng/ml in both test s), and only three (13.6%) of the GHD patients had concomitant low IGF-I le vels (i.e. -2 SD below the normal mean) and only one (4.5%) an abnormal IGF BP-3 value (i.e. -2 SD below the normal mean). Among the 26 children with n ormal GH secretion, 21 (80.8%) also showed normal IGF-I and IGFBP-3 levels, three (11.5%) had a concomitant low IGF-I value and two (7.7%) a concomita nt low IGPBP-3 value. A significant correlation was found between GH secret ion and age at diagnosis (r=0.26, P<0.05), and between IGF-I and IGFBP-3 (r =0.52, P<0.0001), but not between GH and IGF-I or IGFBP-3. Comparing the gr owth pattern of these patients from diagnosis to the first year after thera py or BMT, we found that while individual height changes did not correlate with the GH peak, a significant correlation was found between height SDS de crease and IGF-I (r=0.31, P<0.05) or IGFBP-3 SDS (r=0.37, P<0.01). Conclusion: Our results indicate that the cut-off of -2 SD for IGF-I and IG FBP-3 was insensitive in screening for GHD. A normal value did not exclude a subnormal GH response to provocative tests and therefore although IGF-I a nd IGFBP-3 levels may be indicators of the growth pattern, they cannot be u sed alone as a tool for identifying GHD children after treatment for childh ood malignancy.