Evaluation of ambulatory arterial stiffness index in hyperthyroidism

Background/aim: Hyperthyroidism causes hemodynamic changes that are associated with adverse cardiovascular outcomes. Twenty-four-hour ambulatory blood pressure monitoring recordings provide us with some essential data: BP variability and ambulatory arterial stiffness index (AASI). In this study, we aimed to investigate AASI and short-term BP variability in both overt and subclinical hyperthyroidism and their relationship with thyroid hormones. Materials and methods: We enrolled 36 patients with subclinical hyperthyroidism, 23 patients with overt hyperthyroidism, and 25 healthy euthyroid controls. ABPM recording was performed for 24 h for all patients. Results: There were no statistically significant differences among the 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 was significantly higher in patients with overt hyperthyroidism than in 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-h systolic and diastolic BP, variability of systolic and diastolic BP, and fT4 were independent predictors of AASI (r2 = 0.460, P < 0.001). Conclusion: Although AASI did not differ between overt and subclinical hyperthyroidism, there was a positive relationship between AASI and free thyroid hormone levels. Furthermore, short-term BP variability was higher in overt hyperthyroidism than in subclinical hyperthyroidism.