Acute Coronary Syndrome is one of the leading causes of morbidity and mortality in India and in worldwide. The thyroid hormonal changes could result in the functional derangement of the cellular metabolism and affecting almost all the organs, the heart in particular. The thyroidal hormonal change occurring in the setting of acute stress condition like sepsis, acute coronary syndrome etc., is termed as Sick Euthyroid Syndrome. This condition is characterized by low T3, raised rT3 and normal levels of T4, FT3, FT4 and TSH. This change in thyroid function is thought to be associated with the mechanism involved in maintaining energy in face of altered systemic homeostasis caused by the acute ischemic event or directly related to inflammatory cytokines, acting as an inflammatory marker or both. This study assessed the prevalence of Sick Euthyroid Syndrome (SES) in patients with Acute Coronary Syndrome (ACS). This study also assessed the distribution of SES in ACS and the correlation between thyroid hormone profiles with the outcome. The prevalence of the Sick Euthyroid Syndrome (SES) is as high as 25% i.e. one quarter of ACS patients had SES. The prevalence of SES in old age group was low as compared to younger population. Sick Euthyroid state significantly associated with High BMI, CRP positivity and this condition associated with worst outcome. Sick Euthyroid state not correlated significantly with sex, diabetic state, hypertension, dyslipidemia and smoking. The T3 and rT3 levels well correlated with the poor outcome among Sick Euthyroid Syndrome patients. Also, the Sick Euthyroid state significantly associated with poor outcome. Hence the Sick Euthyroid State serves as an important predictor of worst prognosis in patients with Acute Coronary Syndrome
