Does Treatment of Either Hypothyroidy or Hyperthyroidy Affect Diurnal Blood Pressure

Thyroid hormone has well recognized effects on the cardiovascular system. The purpose of this study was to define the influence of treatment of either hypothyroidism and hyperthyroidism on the values and circadial variations of arterial blood pressure measured by ambulatory blood pressure monitoring.

The study was carried out on 30 hypothyroidic and 30 hyperthyroidic patients without hypertension and 46 healthy participants. First, all the parameters of the groups, then blood pressure values obtained by ambulatory blood pressure monitoring before and after treatment (thyroid hormone replacement with levothyroxine and antithyroid treatment either with propylthyrouracil or metimazole) were compared. For statistical examinations, Shapiro-Wilk, one-way analysis of variance, Kruskal Wallis, post-hoc Tukey, and Wilcoxon Sign tests were used.

In the hypothyroid group, 24-hour mean and diastolic blood pressure, daytime diastolic blood pressure, nighttime mean, systolic and diastolic blood pressures were higher than the control group (P < 0.05). After treatment, 24-hour, daytime and nighttime systolic and diastolic blood pressures diminished. Mean blood pressures diminished only in daytime and nighttime. In the hyperthyroid group, 24-hour average and daytime systolic, mean blood pressures, and all nighttime blood pressure values were higher than the control group (P < 0.05). After treatment, 24-hour and daytime systolic, mean blood pressures, all nighttime pressures diminished (P < 0.05).

Throughout 24 hours, in hypothyroidic patients especially higher diastolic and in hyperthyroidics especially higher systolic blood pressures were exhibited than euthyroid subjects. After treatment of these diseases, ambulatory blood pressure values decreased. Early control of thyroid dysfunctions may help to protect cardiovascular system from hazardous effects of thyroid dysfunctions and lower mortality and morbidity in these patients.