Early Detection of Abnormal Growth Associated with Juvenile Acquired Hypothyroidism

Abstract

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 [THDEVSDS] 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 THDEVSDS 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.

Keywords: child; growth monitoring; hypothyroidism; screening; sensitivity and specificity.