Thyroid hormones as a potential prognostic markers for neonates with hypoxic ischemic encephalopathy

BACKGROUND: Hypoxic ischemic encephalopathy (HIE) is one of the most important causes of mortality and morbidity in newborns. Few studies with conflicting results have been conducted on the effect of perinatal asphyxia and thyroid hormones METHODS: A total of 96 newborns (46 patients with HIE and 50 controls) were included in the study. Electroencephalography (EEG) results, cranial magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), Sarnat Stages, and the presence of seizures of the HIE group were recorded. Thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels of all cases were also measured between 5-10 days. Patients with HIE were separated into 3 groups according to the fT4 (≤1.52 ng / dL, 1.52-1.84 ng / dL, and ≥1.84 ng / dL), and TSH (≤2.56 IU / mL. 2.56-5.3 1IU / Ml, and ≥5.31 IU / mL) levels. RESULTS: All the newborns with seizures were in the 1st or 2nd tertiles of fT4, none of those with high fT4 (>1.84 ng/dL), and the difference was statistically significant (x2=6.61; p=0.036). A negative correlation was determined between fT4 level and duration of hospitalization (=-0.43; p=0.03), duration of respiratory support (r=-0.32; p=0.029), duration of intubation (r=-0.40; p=0.006), and time to full oral feeding (r=-0.40; p=0.006). The TSH level was only correlated with the duration of hospitalization (r=-0.34, p=0.02). CONCLUSIONS: Free T4 level may be used as a prognostic marker in newborns with HIE. Further multicenter, larger, and prospective studies are needed to support and confirm these findings.