Non-thyroidal illness syndrome and cardiopulmonary bypass in children with congenital heart disease

The thyroid hormones (T4 and T3) affect all tissues and impact all metabolic pathways. After heart surgery using cardiac bypass, serum T3 decreases and remains low for at least 24 hours. Several studies on pediatric patients have reported a reduction in the thyroid hormones after heart surgery. This study aimed to investigate the status of thyroid function tests in children with cardiopulmonary bypass surgery. This study was carried out based on the available data on 132 children aged 1 to 1 month to 15 years suffering from congenital heart disease. The patients underwent open heart surgery in Rajaie Cardiovascular, Medical and Research Center in Tehran, Iran from January 2010 to November 2010.The thyroid hormone levels of the patients were measured shortly after admission, immediately postoperatively in the intensive care unit (ICU), and thereafter at 12, 24, and 48-hour intervals. The patients’ gender, age, weight, body mass index, heart disease details, previous cardiac surgeries, and cardiac surgery-related data such as pump time, aortic clamping time, hypothermia duration, postoperative hemodynamic status in the ICU, and postoperative use of inotropic drugs were recorded and statistically analyzed. All patients showed a decrease in T3, T4, and TSH and an increase in T3 resin uptake (T3RU) after surgery. Eventually, 3 (3.2%) patients died after surgery. Preoperatively, there was a significant association between the reduction in the thyroid hormone levels and inotropic drugs administered following surgery as well as the type of the heart disease (p<0.05). There is an important possibility to decrease the thyroid hormone levels of children with congenital heart disease undergoing cardiopulmonary bypass surgery; due to inotropic drugs administered following surgery and the type of heart disease. Therefore, it is recommended that thyroid hormone levels be measured pre-and postoperatively.