Serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels in children with zinc deficiency and the effect of zinc supplementation on these parameters.

AIM: To determine the effect of zinc (Zn) therapy on serum insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) levels in children with Zn deficiency and growth retardation, but without systemic disease, and to investigate the effect of Zn supplementation on these parameters.
METHODS: Twenty-nine children (11 girls and 18 boys) were included. Blood samples were obtained for serum IGF-I and IGFBP-3 determination before and after 50 mg/day Zn supplementation for two months.
RESULTS: The mean age of the children was 11.0 +/- 3.1 years (range 3.7-16.2 years). Serum IGF-I and IGFBP-3 levels were below the mean values in 28 (96.6%) and all children, respectively. After Zn therapy, serum IGF-I levels were increased in 62% of the children; this increase was statistically significant in 48.3% of the children. Serum IGFBP-3 levels were significantly increased in 10 children. There was a positive correlation between serum Zn level and bone age, and serum IGF-I and IGFBP-3 levels. A positive correlation was present between BMI (r = 0.485, p < 0.001) and serum IGF-I levels before therapy.
CONCLUSION: Serum IGF-I and IGFBP-3 levels were decreased in children with Zn deficiency, and were increased after Zn supplementation. In addition, after Zn supplementation, increment of serum IGF-I levels was found to be higher in children with low BMI than those with normal BMI; therefore, the nutritional status of children may also be important, as well as Zn supplementation. Additionally, the determination of higher variation percentile of serum IGF-I level in prepubertal children compared to pubertal children was an interesting finding and necessitates further investigation.