Circulating atrial natriuretic peptides in hyperthyroidism and hypothyroidism.

Plasma concentrations of atrial natriuretic peptides were measured in 32 normal control subjects, 25 patients with hyperthyroidism, and 18 patients with hypothyroidism. Atrial natriuretic peptide values were measured before and after successful therapy with methimazole or 1-thyroxine. Plasma atrial natriuretic peptide concentration was increased in patients with hyperthyroidism (48.0 +/- 19.5 pg/ml) but was decreased in patients with severe hypothyroidism (16.3 +/- 5.7 pg/ml) compared with values in normal control subjects (31.2 +/- 9.5 pg/ml). There was no significant difference between values in normal control subjects and mildly hypothyroid patients (35.0 +/- 12.2 pg/ml). The plasma atrial natriuretic peptide concentration was correlated with the serum thyroxine level and heart rate. The elevated atrial natriuretic peptide concentration in hyperthyroidism decreased, whereas the reduced atrial natriuretic peptide concentration in severe hypothyroidism increased, compared with the initial value after successful therapy. These results suggest that plasma atrial natriuretic peptide concentration is frequently increased in hyperthyroidism and is frequently decreased in severe hypothyroidism, and that thyroid hormone is one of the regulatory factors for circulating atrial natriuretic peptides.