Early Detection of Abnormal Growth Associated with Juvenile Acquired Hypothyroidism

Context Development of the typical growth phenotype in juvenile acquired hypothyroidism (JHT), the faltering linear growth with increasing weight, has not been thoroughly characterized. Objective To describe longitudinal growth pattern in children developing JHT and investigate how their growth differs from the general population in systematic growth monitoring. Design Retrospective case-control study. Setting JHT cases from 3 Finnish University Hospitals and healthy matched controls from primary health care. Patients A total of 109 JHT patients aged 1.2 to 15.6 years (born 1983-2010) with 554 height and weight measurements obtained for 5 years preceding JHT diagnosis. Each patient was paired with 100 healthy controls (born 1983-2008) by sex and age. Longitudinal growth pattern was evaluated in mixed linear models. Growth monitoring parameters were evaluated using receiver operating characteristics analysis. Results At diagnosis, JHT patients were heavier (mean adjusted body mass index-for-age [BMISDS] difference, 0.65 [95% CI, 0.46-0.84]) and shorter (mean adjusted height-for-age deviation from the target height [(THSDS)-S-DEV] difference, -0.34 [95% CI, -0.57 to -0.10]) than healthy controls. However, 5 years before diagnosis, patients were heavier (mean BMISDS difference, 0.33 [95% CI, 0.12-0.54]) and taller (mean (THSDS)-S-DEV difference, 0.29 [95% CI, 0.06-0.52]) than controls. JHT could be detected with good accuracy when several growth parameters were used simultaneously in screening (area under the curve, 0.83 [95% CI, 0.78-0.89]). Conclusions Abnormal growth pattern of patients with JHT evolves years before diagnosis. Systematic growth monitoring would detect abnormal growth at an early phase of JHT and facilitate timely diagnosis of JHT.