The effect of thyroid dysfunction on N-terminal pro-B-type natriuretic peptide concentrations.

BACKGROUND

B-type natriuretic peptides and N-terminal pro-B-type natriuretic peptides (NT-proBNP) have been suggested as being useful for the diagnosis of congestive heart failure. We have shown previously that changes in thyroid function are associated with changes in concentrations of other low molecular weight molecules. Therefore, the aim of this study was to assess whether similar changes occurred with NT-proBNP concentrations following treatment of thyroid dysfunction.

METHODS

Seventeen patients (12 female, 5 male, age range 24-77 years) with newly diagnosed hypothyroidism and 21 patients (16 female, 5 male, age range 21-66 years) with newly diagnosed hyperthyroidism had NT-proBNP measured at baseline and when they subsequently became euthyroid.

RESULTS

NT-proBNP levels were not significantly different in the hyperthyroid group from the hypothyroid, either before (P = 0.706) or after treatment to euthyroidism (P = 0.170). The hypothyroid group showed a rise in NT-proBNP after treatment (P < 0.001). There was a marginally significant fall in the NT-proBNP levels in the hyperthyroid group (P = 0.05). However, these changes were within the expected wide range of biological variability of NT-proBNP shown in earlier studies.

CONCLUSIONS

Hypothyroidism alters NT-proBNP concentrations, but the magnitude of this effect may be lost in the wide biological variability of natriuretic peptides and this statistically significant finding is not likely to be of clinical relevance.