Prevalence of congenital hypothyroidism and transient neonatal hyperthyrotropinemia in babies born to hypothyroid mothers at a tertiary care hospital

Abstract

Objectives: Transient neonatal hyperthyrotropinemia (TNH) is being increasingly recognized in the developed world as a risk factor for the development of permanent hypothyroidism. It is defined as transient elevation of serum thyroid-stimulating hormone (TSH) levels between 10 and 20 mIU/L after 48 h of life with normal free thyroxine levels, returning to normal after 2 weeks of life. Factors associated with TNH as well as its consequences on growth and development are lesser known at present. Maternal hypothyroidism, both overt and subclinical, is known to have adverse neurodevelopmental outcomes in children. Maternal hypothyroidism is also one of the risk factors for developing TNH. This study aimed to measure the prevalence of congenital hypothyroidism (CH) and TNH, and evaluate neurodevelopmental outcomes in children born to hypothyroid mothers. Material and Methods: Sixty-three consecutive neonates born to mothers diagnosed as hypothyroid during pregnancy were enrolled for the study. Fifty neonates underwent evaluation for thyroid functions and development till 6 months of age, after excluding preterm and sick babies requiring intensive care. Results: None of the babies had CH. The prevalence of TNH was found to be 6.0% (n = 3/50), with TSH values normalizing by 4 weeks of age. All babies with TNH were female. Development assessment done till 6 months of life was normal for all babies. Conclusion: Our study describes the prevalence of TNH and short-term development outcomes in babies born to hypothyroid mothers. The role of TNH in the development of permanent hypothyroidism is still a debatable topic, and larger studies are needed to assess its implications on linear growth, academic performance, as well as language and intellectual development.