Prospective observational study of effects of cardiopulmonary bypass in cardiac surgery on thyroid function tests in euthyroid patients and in patients on thyroid medications

Cardiopulmonary bypass used in various cardiac surgeries has effects on various organ systems. This study intends to observe effects of cardiopulmonary bypass on thyroid function tests. Patients posted for cardiac surgery with cardiopulmonary bypass will be recruited in the study. After thorough pre-operative assessment, their pre-operative Thyroid function values (Serum Free T3, Serum Free T4 and Serum TSH) will be recorded. Presence or absence of any previous thyroid disorder will be recorded along with thyroid medications. Surgery will be conducted under standard protocol. Total cardiopulmonary bypass duration, aortic cross clamp duration, temperature and perfusion pressure during bypass duration will be recorded. Thyroid functions tests (Serum Free T3, Serum Free T4 and Serum TSH) will be repeated 24 hours after surgery. Difference in Thyroid function will be analyzed for statistical significance. At the same time, correlation of the difference in Thyroid function tests with post operative ICU course will be observed and analyzed for statistical significance.