B-type natriuretic peptide in patients with clinical hyperthyroidism

Aims: To investigate the level and clinical significance of plasma B-type natriuretic peptide (BNP) in patients with hyperthyroidism. Methods: Plasma BNP was measured in 32 healthy subjects and 67 patients with clinical hyperthyroidism. Left ventricular anatomy and function was assessed with echocardiography. Results: The average BNP in hyperthyroid patients was higher than that in healthy subjects (186±140 vs 34±17 ng/l, p =0.001). The increase in BNP was mainly found in hyperthyroid patients who had clinical and echocardiographic evidence of left ventricular dysfunction (250±190 ng/l). The BNP level in patients with hyperthyroidism, but with normal left ventricular function, was similar to that of the controls (37±17 vs 34±17, ng/l, p > 0.05). Multi-regression analysis showed that left atrial diameter and left ventricular ejection fraction were independently associated with the plasma levels of BNP. Conclusions: there is a significant elevation in plasma BNP in patients with hyperthyroidism; the increase is largely due to hyperthyroidism-induced left ventricular dysfunction. Measurements of plasma BNP may help to detect heart failure in patients with clinical hyperthyroidism.