Normalized growth velocity in children with Down's syndrome during growth hormone therapy.

Between 6 months and 3 years of age, growth velocity in children with Down's syndrome (DS) is markedly reduced in comparison to that of healthy children. However, after 3 years of age, it is almost normal. Thus, growth retardation becomes pronounced during the period when growth hormone (GH) starts to regulate growth. The present authors report the long-term effects of GH-therapy in 16 children with DS, who are being treated for 3 years from the age of 6-9 months. The treatment, Genotropin, 0.1 U kg-1 BW day-1, was started at a mean age of 7.4 (6-9) months. The results after 12 (n = 16), 24 (n = 12) and 30 (n = 8) months are presented. The mean height standard deviation score, SDS (range; Swedish standard), before therapy was -1.8 (-0.5 to -3.1) and the mean head circumference was -1.2 (-0.4 to -3.5). After 12, 24 and 30 months, the mean height SDS were -1.1 (-0.8 to -1.9), -0.9 (0 to -1.5) and -0.9 (0.1 to -1.5) and the mean head circumference SDS were -1.1 (0 to -2.5), -1.1 (0 to -2.2) and -1.2 (-0.5 to -2.0), respectively. During hGH-treatment, the children with DS thus gained height during the first year, and then followed the growth rate of healthy Swedish children. When compared to growth charts for children with DS the mean height of these children started at the fiftieth centile and reached the ninety-fifth centile after 24 months of treatment. Head circumference only slightly increased during the therapy, and not to the same extent as height. This indicates that small head circumference in DS is not only an effect of growth retardation, but also due to microcephaly.