Linear growth, growth-hormone secretion and IGF-I generation in children with neglected hypothyroidism before and after thyroxine replacement

Abstract

We studied growth hormone (GH) stimulation and insulin-like growth factor -I (IGF-I) generation tests in 15 children with neglected congenital hypothyroidism (CH) (age = 6.4 ± 4.2 years) and measured their growth parameters for > 1 years after starting thyroxine (T4) replacement. One year after treatment, height SDS (HtSDS) increased from -4.3 ± 2.5 to -2.7 ± 2.3. Peak GH response to clonidine increased from 3.2 ± 1.2 ng ml-1 to 7.62 ± 1.38 ng ml-1 after treatments. Basal and peak IGF-I response to GH increased from (34.66 ± 17.3 ng ml-1 and 58.4 ± 36.99 ng ml -1, respectively) before treatment to (130.6 ± 97.8 ng ml-1 and 193.75 ± 122.5 ng ml-1, respectively). HtSDS increments were correlated significantly with basal free T4 concentrations (r = 0.622, P < 0.01). In summary, after long period of hypothyroidism, T4 replacement produced significant, although incomplete, catch-up growth through a partial recovery of GH- IGF-I axis. © The Author [2008]. Published by Oxford University Press. All rights reserved.