Thyroid Hormone Abnormalities in Septic Neonates: A Prospective Study

摘要

Introduction: Thyroid abnormalities are common in neonates with sepsis and non-thyroidal critical illness. Alteration of thyroid function in septic neonates is mediated by various cytokines as a nonspecific response. Alteration of thyroid hormone abnormalities can adversely impact prognosis in children with critical illness. There is paucity of studies regarding thyroid hormone function in neonates with sepsis and relation between thyroid hormone abnormalities and risk of mortality. Aim: To compare mean serum levels of T3, T4, TSH, Free T3 and Free T4 levels between neonates with sepsis and gestational age matched normal controls and to assess severity of thyroid hormone abnormalities at admission between non-survivors and survivors among septic neonates. Materials and Methods: The prospective study was done in a level III neonatal intensive care unit. Neonates who were admitted with diagnosis of sepsis beyond day 3 of life were recruited as cases. Normal gestation matched neonates beyond day 3 were enrolled as control. Total 51 cases and 48 controls were enrolled in the study. Thyroid Function Tests (TFTs) were obtained at enrollment. Cases were divided into ‘survivors’ (86.3%) and ‘non-survivors’ (13.7%). Analysis was done using statistical software packages SPSS and Microsoft Excel. Comparison of mean levels of thyroid hormones between cases and controls was done by t-test or Mann-Whitney U test. Results: Serum T3, T4, Free T3 and Free T4 levels were significantly lower among cases as compared to gestational age matched control. {For both groups respectively T3: median (IQR) 69 (55,112) vs. 118 (81.5,142), p=0.002; for T4: 8.3 (5.9,11.7) vs. 12.7 (11.3,16.9) p0.001; Free T3: 2.1 (1.7,2.6) vs. 3.1 (2.4,3.4) p=0.002; Free T4: 1.18 (0.9,1.48) vs. 1.72 (1.46,2.05), p0.001}. TSH was not significantly different among the groups. The non-survivors among cases had significantly lesser T3,T4 and Free T4 levels as compared to survivors. {For both groups respectively T3:median (IQR) 38 (34,48) vs. 89 (61.2,112), p0.001; for T4: 6.2 (5.9,7.5) vs. 9 (6.4,12) p0.001; Free T4: 1.12 (0.87,1.18) vs. 1.2 (0.95,1.5) p=0.02}. Rest of the TFTs were similar in both the groups. Conclusion: Neonatal sepsis causes significant decrease of thyroid hormones. Non survivor group of Septic neonates had significant low levels of T3 and T4 at admission. Low T3 and T4 levels at admission may serve as prognostic indicator in neonatal sepsis.