STUDY OF THYROID FUNCTION TEST ABNORMALITIES IN PATIENTS WITH ACUTE CORONARY SYNDROME
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Aim of work: The aim of this work is to study thyroid function test abnormalities in patients with acute coronary syndrome to illustrate their possible role in the progression and the severity of the disease. Patients and methods: The study was performed on 80 patients (51 males and 29 females) selected from those admitted at Intensive Care Unit of Bertha University Hospitals with acute coronary syndrome after exclusion of diseases and drugs that affect the thyroid function tests. Their ages ranged from 47 to 72 years (with a mean age of 53 ± 3.3). They were classified into 2 groups: group I includes 30 patients with unstable angina (VA) and group II includes 50 patients with acute myocardial infarction (AMI). Twenty healthy subjects were selected as a control group and matched with other groups regarding age, sex, and residence. Results: The mean levels of total tri-iodothyronine (TT3) and free T3 (FT3) were significantly decreased while the mean levels of reverse triiodothyronine (rT3) were significantly increased in patients with VA and AMI in compare to the controls (P<0.05 respectively). However, there were no statistical significant difference in the mean levels of total tetra- iodothyronine (TT4), free Ty (FT4) and thyroid stimulating hormone (TSH) in UA and AMI in compare to the controls (P>0.05 respectively). According to the classification of patients with AMI into those with left ventricular ejection fraction (LVEF) <=50% (group-A) and those with LVEF >50% (group-B), the mean levels of total tri-iodothyronine (TT3) and free T3 (FT3) were significantly decreased with a concomitant significantly rise of reverse T3 (rT3) in group-A compared to group-B (P<0.05 respectively) while the mean levels of total thyroxine (TT4), free Ty (FT4) and TSH tended to be higher in group-A without a statistical significant difference (P>0.05 respectively). There were significant positive correlations between TT3, FT3 and LVEF (P<0.05 respectively). In patients with complicated infarctions, the decrease in the mean levels of TT3 and FT3 and the increase of the mean levels of rT3 were significantly greater compared to those with uncomplicated infarctions (P<0.05 respectively). Also, the mean levels of TT4, FT4 and TSH were significantly decreased in complicated infarctions (P<0.05 respectively). On follow up of cases with AMI, the decrease in the mean levels of 'both TT3 and FT3 and the increase in the mean levels of rT3, at the onset of their admission, were statistically significant in those who had died compare to those who had lived (P<0.05, respectively). Conclusion: It is concluded from this study that the thyroid function test abnormalities occur not only in AMI but also in VA. The degree of T3 decrease is proportional to the severity of cardiac damage and may have a possible prognostic value. Patients with a mild decrease in serum T3 may be of cardioprotective value. However, mortality was high among patients with the most pronounced thyroid level depression, indicating that down-regulation after AMI may be maladaptive. Recommendation: Large-scale studies of T3 therapy are required in the setting of haemodynamic instability following AMI.