Effects of cardiovascular drugs on TSH serum levels in patients on replacement therapy after thyroidectomy.

OBJECTIVE Hypothyroidism is one of most common endocrine disorders resulting from deficiency of thyroid hormones. The aim of our study was to investigate whether cardiovascular drugs as well as gender, age, body-mass index, and habits, like smoking or drinking coffee affect thyroid-stimulating hormone (TSH) level in hypothyroid patients with thyroxine replacement therapy who suffer from cardiovascular disease. MATERIALS The study was conducted on 150 hypothyroid patients who underwent total thyroidectomy for benign reasons; they were divided into five treatment groups: levothyroxine only group and, according to the drugs they had in therapy alongside levothyroxine, the angiotensinconverting enzyme inhibitors group, the selective β-blockers group, the calcium antagonists group, as well as the nitrates group. A retrospective cohort study was conducted in the Clinical Center Kragujevac, Serbia, during the period of January 2012 to October 2014. All patients' data were collected both from participants' health records and questionnaires that patients completed, including data about habits, like smoking or drinking coffee. RESULTS TSH values were significantly higher in the group of patients with selective β-blockers in therapy alongside levothyroxine, compared to all the other study groups. The values of TSH level did not significantly differ among the other therapy groups. On the other hand, cigarette smoking was a risk factor that decreased TSH levels in patients on thyroid replacement therapy. CONCLUSIONS Our study shows that selective β-1 blockers can increase, while cigarette smoking can decrease TSH serum levels in hypothyroid patients on thyroid-replacement therapy.