THYROID HORMONE LEVELS IN NEONATAL HYPERBILIRUBINEMIA

BACKGROUND Neonatal jaundice affects 60% of full-term infants and 80% of preterm infants in the first three days of life. Congenital Hypothyroidism (CH) is one of the most common preventable causes of mental retardation in children. Early diagnosis and treatment prevent the devastating outcome of mental retardation. Studies have stated that hypothyroidism is one of the aetiologies in severe hyperbilirubinemia. Prolonged jaundice is sometimes associated with congenital hypothyroidism, which appears to be associated due to delayed maturation of hepatic uridine diphosphate glucuronyl transferase enzyme activity. The purpose of this study was to investigate a relationship if any between neonatal thyroid-stimulating hormone (TSH), thyroxin (T4) and increased levels of total bilirubin levels in the blood. The aim of this study is to measure association between bilirubin levels and thyroid abnormality in new-borns. in mothers. Out of these, the neonates having serum total bilirubin < 15 mg/dL were considered as controls and neonates with serum total bilirubin > 15 mg/dL were considered as cases (i.e. neonates with severe hyperbilirubinemia are considered as cases). We have selected 35 cases and 35 controls. The sample size was taken for convenience during the study. We have performed thyroid profile in these neonates to see any association between hyperbilirubinemia and thyroid dysfunction, as thyroid dysfunction is one of the causes of pathological jaundice. We have taken cut-off of 15 mg/dL as less than 15 mg/dL of bilirubin is considered as physiological jaundice. The thyroid hormone levels in the present study were evaluated after 72 hours of postnatal age to avoid physiological changes in the hormonal levels during first 3 days of life. Bilirubin estimation was done by diazo method in fully automated analyser. Thyroid profile, i.e. T3, T4 and TSH were estimated in fully automated immunoassay analyser method by ECLIA (Electrochemiluminescence Immunoassay).