Evaluation of catch-up growth in severe pediatric Hashimoto's hypothyroidism

BackgroundWe aimed to evaluate catch-up growth in children with severe Hashimoto's hypothyroidism (HH) after thyroid hormone replacement therapy (HRT).MethodsA multicenter retrospective study was conducted including children referred for growth slowdown that led to the diagnosis of HH between 1998 and 2017.ResultsA total of 29 patients were included, with a median age of 9.7 years (13–172 months). Median height at diagnosis was -2.7 [-4.6; -0.1] standard deviation score (SDS), with a height loss of 2.5 [0.7; 5.4] SDS compared to height before growth deflection (p<0.0001). At diagnosis, the median TSH level was 819.5 mIU/L [100; 1844], the median FT4 level was 0 pmol/L [undetectable; 5.4], and the median anti-thyroperoxidase antibody level was 1601 UI/L [47; 25,500].In the 20 patients treated only with HRT, there were significant differences between height at diagnosis and height at 1 year (n = 19, p<0.0001), 2 years (n = 13, p = 0.0005), 3 years (n = 9, p = 0.0039), 4 years (n = 10, p = 0.0078), and 5 years (n = 10, p = 0.0018) of treatment but not in the case of final height (n = 6, p = 0.0625). Median final height was -1.4 [-2.7; 1,5] SDS (n = 6), with a significant difference between height loss at diagnosis and total catch-up growth (p = 0.003).The other nine patients were also given growth hormone (GH). They were smaller at diagnosis (p = 0.01); however, there was no difference in final height between those two groups (p = 0.68).ConclusionSevere HH can lead to a major height deficit, and catch-up growth seems to be insufficient after treatment with HRT alone. In the most severe cases, administration of GH may enhance this catch-up.