Endocrine Abstracts

Hyperthyroidism whether endogenous or exogenous in origin causes hemodynamic changes which associated with adverse cardiovascular outcomes. Ambulatory arterial Stiffness index (AASI) is a non invasive way of measuring arterial stiffness. Short term BP variability is derived from 24-hour ambulatory blood pressure monitoring (ABPM) recordings. BP variability and AASI are associtaed with increased cardiovascular risk.

We aimed to investigate AASI and short term BP variability in both overt and subclinical hyperthyroidism and their relationship with thyroid hormones.

We enrolled 59 patients with hyperthyroidism and 25 healthy euthyroid controls in the study. The hyperthyroid group included 36 patients with subclinical hyperthyroidism and 23 patients with overt hyperthyroidism. There were no statistically significant differences among overt hyperthyroidism, subclinical hyperthyroidism and control groups in terms of AASI (0.43±0.15, 0.38±0.12, 0.42±0.13, respectively; P=0.315). Variability of diastolic BP, as expressed by 24-hour diastolic CV, was significantly higher in patients with overt hyperthyroidism than patients with subclinical hyperthyroidism (14.8±2.6 vs 12.8±2.5%, P=0.023). There were significant positive correlations between AASI and fT3 (r=0.246, P=0.02) and fT4 (r=0.219, P=0.04) while TSH was not correlated with AASI (r=0.023, P=0.838). After adjusting for confounders, age, 24-hour systolic and diastolic BP, variability of systolic and diastolic BP (24-hour systolic and diastolic CV) and fT4 were independent predictors of AASI (r²=0.460, P<0.001). Our study showed that AASI did not differ between overt and subclinical hyperthyroidism whereas short term BP variability was higher in overt hyperthyroidism than subclinical hyperthyroidism. Also, there was a positive relationship between AASI and free thyroid hormones.