Effects of Cardiopulmonary Bypass on Thyroid Function and Need of Prophylactic Low-Dose Thyroxine for Post-operative

ABSTRACT

Introduction: Cardiopulmonary bypass (CPB) is associated with well-described changes in thyroid hormone levels, consistentwith what is described as the euthyroid sick syndrome.Aim: This study aims to evaluate thyroid hormone changes and their association with post-operative care in low-risk patientsundergoing cardiac surgery with CPB.Materials and Methods: Fifty patients with euthyroid were included; no one received drugs with a known influence on thyroidstatus at the time of the operation. Eighteen of the patients had coronary artery bypass surgery, 29 had a single valve replaced,and 3 had both valve replacement. Blood samples were collected 6 h after surgery and on the 3rd postoperative days (POD).Results: Thyroid-stimulating hormone (TSH) levels were raised in 10 patients and free T3 level reduced in 14 patients in theearly post-operative period and TSH raised in 4 patients and free T3 reduced in 6 patients during the 3rd POD. Number of thecases with normal TSH is 36, free thyroxine [T4] remained within the normal range in all patients throughout the study.Conclusion: There is an advantage of prophylactic administration low dose of thyroxine to all cardiac patients, especially femalepatient who undergoes surgery to improve the general condition of the post-cardiac surgery patients.