Background and aim: It was known that NT-proBNP levels increased in cardiac failure. But, NT-proBNP levels in different thyroid status still unclear. We aimed to evaluate serum NT-proBNP levels in both of hyperthyroid and hypothyroid patients without cardiac insufficiency.
Subjects and methods: Thirty nine patients with hyperthyroidism (43.0±16.5 yr), 25 patients with hypothyroidism (35.4±13.9 yr) and 34 ages matched euthyroid subjects (41.4±13.8 yr) were included to study. After all anthropometric evaluations, body fat analyses were determined with bioelectrical impedance. Electrocardiography and echocardiography were used in cardiac evaluations. Serum NT-proBNP was measured with immunoassay.
Results: Mean serum NT-proBNP levels in hyperthyroid patients was higher than both of control subjects (P=0.02) and hypothyroid patients (P=0.03). But, mean serum NT-proBNP levels in hypothyroid patients was not different from control subjects. There was a positive correlation between serum NT-proBNP and thyroid hormones (NT-proBNP and fT3: r=0.316, P=0.002; NT-proBNP and fT4: r=0.284, P=0.006, respectively). Serum NT-proBNP levels were positively correlated with left ventricle end-diastolic diameters (r=0.317, P=0.006), interventricular septum thickness (r=0.395, P=0.001), left ventricle posterior wall thickness (systolic) (r=0.301, P=0.01), left atrial dimension (r=0.609, P=0.0001) and negatively correlated with left ventricular ejection fraction (r=−0.338, P=0.003).
Conclusions: Hyperthyroidism may affect serum NT-pro-BNP levels independent of cardiac insufficiency. NT-proBNP values were increased in hyperthyroidism. Hyperthyroidism may lead to cardiac dysfunction undetermined with conventional echocardiography and these undetermined changes in cardiac functions may lead to elevation of NT-proBNP levels.