Abstract

AIM: To determine the effects of dopamine infusion on thyroid hormones in patients who had undergone coronary bypass surgery. MATERIAL AND METHOD: Patients who had not had thyroid gland disease pre-operatively were enrolled in this observational study. The patients who were not administered dopamine infusion formed the control group (GROUP I, n=16), the patients who received dopamine infusion were categorized into three groups as follows: GROUP II (dopamine infusion of 2.5-7.5 µg/kg/min; n=11), GROUP III (dopamine infusion of 10-20 µg/kg/min; n=12), and GROUP IV (dopamine infusion of 20 µg/kg/min or more; n=10). Blood samples were collected pre-operatively and at 2, 8, 16, 24, 48, and 72 hours post-operatively from the patients who were administered dopamine infusions for at least 48 hours post-operatively, The serum T3, free T3, thyroxine, free thyroxine and TSH levels were detected. RESULTS: Twenty-six males and 23 females with a mean age of 62±11 years were included in the study. There were no significant differences between the groups in terms of acute myocardial infarction, left main coronary lesions, and number of grafts, while the left ventricular ejection fraction (LVEF) values were significantly lower in groups III and IV than the rest. While no deaths were observed in the patients in groups I and II, 2 patients (16.6%) from group III and 6 patients (60%) from group IV died during the study. Evaluation of the patients in terms of alterations in thyroid hormone homeostasis demonstrated that T3 and FT3 levels in patients in groups I and II decreased in the early post-operative period and reached the lowest levels 16 hours post-operatively. The T3 and FT3 levels initiated to rise again by the 24th hour and increased to pre-operative levels by 72 hours post-operatively. T4, FT4, and TSH levels were observed to drop significantly by 2 hours post-operatively, increasing to the pre-operative levels by 72 hours post-operatively. Thyroid hormone levels were noted to be low in all measurements performed post-operatively in groups III and IV and reached the lowest levels by 72 hours. CONCLUSION: In this study, thyroid hormone levels were affected significantly on the dose of 7.5 mg / kg / min infusion of dopamine, and this leads to inappropriate TSH response. This iatrogenic hypothyroidism is in parallel with dose of dopamine on and the severity of the situation. We believe that this factor is taken into account the selection of positive inotropic drugs.