Abstract
INTRODUCTION: The causes of congenital hypothyroidism (CHT) are thyroid dysgenesis (TD), dyshormonogenesis (TDH) or transient hypothyroidism (TH). METHODOLOGY: This is a cross-sectional study looking at data over a period of 16 years (2000-2016). Confirmed cases had thyroid scan at the age of 3-years-old and repeated TFT (after 6 weeks off medications). Relevant data was collected retrospectively. RESULTS: Forty (60% female) children with CHT were included in the study. Thirty (75%) children presented with high cord TSH. Nine (23%) presented after 2 weeks of life. Majority were diagnosed with TDH (42.5%) with TD and TH of 40% and 17.5% respectively. Median cord TSH of children with TD was significantly higher compared to TDH and TH (p=0.028 and p=0.001 respectively). L-thyroxine doses were not significantly different between TD, TDH and TH at diagnosis or at 3 years. CONCLUSIONS: TDH is highly prevalent in our population. TD may present after 2 weeks of life. One in five children treated for CHT had TH. Differentiating TD, TDH and TH before initiating treatment remains a challenge in Malaysia. This study provides clinicians practical information needed to understand the possible aetiologies from a patient's clinical presentation, biochemical markers and treatment regime. Reassessing TH cases may be warranted to prevent unnecessary treatment.