Endocrine Abstracts

Introduction: Aminoterminal pro B type natriuretic peptide (NT-pro BNP) is the inactive degradation product of pro BNP. Thyroid diseases are known to have effect on NT-pro BNP levels. In this study, we aimed to determine possible changes in NT-pro BNP levels in patients with thyroid dysfunctions.

Material and method: Fifteen patients with hyperthyroidism, 8 with subclinical hyperthyroidism, 12 with hypothyroidism, 15 with subclinical hypothyroidism and 35 healthy controls were included in the study. The patients were evaluated for cardiac disease by physical examination, electrocardiography, and echocardiography. Those with systemic diseases were excluded from the study. Serum samples were taken for free triiodothyronine (fT₃), free thyroxine (fT₄), TSH, NT-pro BNP before and after achievement of euthyroidism in patients. Control subjects were tested for once.

Results: Basal mean NT-pro BNP level of hyperthyroid group was significantly higher than the control group (101.8±63.0 vs 41.40±23.66 pg/ml, P<0.001). In hypothyroid, subclinical hypothyroid, subclinical hyperthyroid and control groups mean NT-pro BNP levels were similar. Mean NT-pro BNP significantly decreased after achievement of euthyroidism in hyperthyroid group (49.0±20.0 pg/ml, P=0.002). In hypothyroid group, NT-pro BNP levels significantly increased after achievement of euthyroidism (52.75±37.99 vs 79.00±57.96, P=0.015). There was no significant change in NT-pro BNP levels after treatment in subclinical hypothyroidism and hyperthyroidism. Basal NT-pro BNP level was positively correlated with heart rate in hyperthyroid group (r: 0.569, P=0.027) and it was negatively correlated with heart rate in hypothyroid group (r: −0.616, P=0.033).

Conclusion: Studies to date suggest that thyroid hormone is one of the important factors that regulate serum NT-pro BNP level. In hyperthyroidism, NT-pro BNP levels reach the levels observed in severe heart failure. Thus, in patients without severe cardiac dysfunction, elevated NT-pro BNP level may be suggestive for hyperthyroidism.