Growth hormone and insulin-like growth factor I axis and growth of children with different sickle cell anemia haplotypes

Background: The purpose of this study was to examine the relationships betw een growth in children with sickle cell anemia and the different beta -glob in haplotypes, as well as components of the insulin-like growth factor (IGF )/insulin-like growth factor binding protein (IGFBP) axis. Patients and Methods: Growth parameters and plasma concentrations of growth hormone (GH), LGF-1, and IGFBP-3 were studied in 41 children with sickle c ell anemia whose haplotypes were defined. Results: Plasma concentrations of IGF-I (total, free, and free/total fracti on) and IGFBP-3 were significantly reduced in all patients with sickle cell anemia compared with the healthy children. Patients with the CAR/CAR haplo type had significantly lower mean growth velocity compared with those with Ben/Ben. When the GH/IGF axis elements were compared in relation with the d ifferent haplotypes, total IGF-I levels in CAR/CAR patients were significan tly lower compared with levels in patients with Ben/Ben. A positive correla tion was found between hematocrit and total IGF-I and between fetal hemoglo bin percentages and the z-scores for total IGF-I and IGFBP-3. There was a p ositive correlation between age, weight, height, bone age, and the various elements of the GH/IGF-I axis when all groups were considered, although the correlation was lost when the auxologic data were expressed as standard de viation score for age. Growth velocity and the z-score for growth velocity were not correlated with any element of the axis. Conclusions: The positive relationship between hematocrit and fetal hemoglo bin percentages with total IGF-I, free/total IGF-I, and IGFBP-3 in patients with sickle cell anemia could show that the delayed growth of these patien ts may be linked to intrinsic factors of the disease, which also determine the low circulating concentrations of the various elements of the GH/IGF-I axis. It is reasonable to assume that decrease of total IGF-I concentration s in patients with CAR/CAR haplotype is secondary to the severity of the di sease.