Department of Pediatric Disease, School of Medicine, Isfahan University of Medical Sciences and Health Services, Isfahan



Introduction. All neonates should be screened for congenital hypothyroidism in the first week of their lives. To evaluate the reliability of thyroid function tests in neonates who undergone exchange transfusion (ET), we studied the alteration of thyroid hormones after ET in neonates.
Methods. Eighteen full term neonates (gestation age> 37 weeks) undergoing ET due to heperbilirubinemia at neonatal wards of AI-Zahra and Shahid-Beheshti hospitals (affiliated to Isfahan University of Medical Sciences) were studied. All ETs were performed using a double volume exchange of adult donor blood. The age of subjects was five days or more. The patients had not Rh disease and seemed well. Thyroid function was evaluated before the exchange (pre-ET), at the conclusion of the ET (post-ET) and seven days later (by assessment of T3, T4, TSH).
Results. The mean pre-ET, T4 and TSH concentrations were significantly higher than in donor blood. The mean pre-ET, T3 concentration was not statistically different from donor blood. At the end of exchange (post-ET), the mean T4 and TSH concentrations dropped and statistically differed from pre-ET values, whereas the mean post-ET, T 4 and TSH were still significantly higher than the donor blood. The post-ET value was not significantly different from pre-ET, T3 and T3 of donor blood. After 7 days, T 4 and TSH concentrations increased and statistically reached to pre-ET, T 4 and TSH but at this time the mean T3 concentration was significantly higher than pre-ET value.
Discussion. There was significant decrease in concentrations of T 4 and TSH at the end of ET but no difference at seven days later. Therefore, we suggest that the screening of congenital hypothyroidism should be performed either before the ET or after one-week Post Exchange transfusion.


Blood Exchange Transfusion, Thyroid Function Test, Neonatal Medicine, TSH, T4,T3