atrial-natriuretic-factor and Thyrotoxicosis

Serum BNP (brain naturiuretic peptide) and ANP (atrial natriuretic peptide) levels are reportedly elevated in patients with thyrotoxicosis. The increases may not be due to thyrotoxicosis itself but to secondary cardiovascular changes such as chronic heart failure (HF) or atrial fibrillation (AF) which frequently accompany thyrotoxicosis. We measured serum ANP and BNP levels in 130 patients with thyrotoxicosis and correlated them with HF severity and thyroid function. Thirty-seven normal subjects served as controls. Serum BNP levels in thyrotoxic patients were significantly higher than those in control subjects and significantly correlated with serum free T4, free T3 and ANP levels. In untreated Graves' disease serum BNP level was significantly elevated in patients with HF or AF. Multiple regression analysis revealed that HF, free T4, female gender and AF are independent contributing factors to the elevated BNP level, and that these four factors contributed about 40%. On the other hand, HF and AF were contributing variables for ANP level but the overall contribution of these factors was only 10%. After normalization of thyroid function, serum BNP levels were normalized in 70.5% of Graves' patients. BNP level in euthyroid state was dependent on the presence of HF and the BNP value before therapy, but not on thyroid hormone levels or AF. These data suggest that the cardiovascular condition is the major factor responsible for the elevated serum BNP and ANP levels in thyrotoxic patients, while thyrotoxicosis itself is an independent but minor contributing factor. Thus, the determination of serum BNP levels in thyrotoxic patients is useful for monitoring cardiovascular conditions of HF.

Topics: Adult; Aldosterone; Atrial Natriuretic Factor; Case-Control Studies; Female; Graves Disease; Heart Failure; Humans; Male; Middle Aged; Natriuretic Peptide, Brain; Osmolar Concentration; Renin; Renin-Angiotensin System; Thyroid Hormones; Thyrotoxicosis

Plasma immunoreactive atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP), serum thyroxine (T4), triiodothyronine (T3), and thyrotropin (TSH) concentrations were measured in 11 patients with thyrotoxicosis and atrial fibrillation (group 1), in 5 patients with thyrotoxicosis and sinus cardiac rhythm (group 2) and in 8 healthy subjects in comparable age. Patients with thyrotoxicosis were studied before and after treatment with methimazole (3 x 20 mg daily) during 10 days. During treatment sinus cardiac rhythm returned in 6 patients with initial fibrillation (group 1a) while 5 patients still presented atrial fibrillation at the end of the study (group 1b). All patients from group 2 maintained a sinus cardiac rhythm throughout the study. Median plasma concentrations of ANP and cGMP before treatment in patients from group 1 were higher: 43.8 pmol/l and 11.0 nmol/l, respectively than in patients from group 2: 20.0 pmol/l (p < 0.005) and 6.5 nmol/l (p < 0.01), respectively. In all groups of patients methimazole treatment resulted in a significant decrease of plasma ANP and cGMP concentrations in parallel to a reduction of serum T3 and T4 levels. After therapy, plasma ANP and cGMP levels in patients from group 1a were not significantly different from those in patients from group 2, while in patients from group 1b remained slightly elevated. Presented results suggest that atrial fibrillation in patients with thyrotoxicosis represents an important factor augmenting plasma ANP and cGMP levels, in addition to the stimulatory effect exerted by thyroid hormones. However, the marked reduction of serum thyroid hormones produced by short-term methimazole treatment in patients with thyrotoxicosis was associated with parallel decrease of plasma ANP and cGMP levels toward normal values. Therefore, the influence of thyroid hormones on plasma ANP and cGMP concentrations seems relatively more important than the effect of atrial fibrillation.

Topics: Adult; Atrial Fibrillation; Atrial Natriuretic Factor; Cyclic GMP; Female; Humans; Methimazole; Middle Aged; Thyroid Hormones; Thyrotoxicosis

We measured plasma atrial natriuretic peptide (ANP) levels in 17 patients with newly diagnosed thyrotoxicosis. ANP was elevated compared to a group of healthy controls and fell to normal after treatment. Plasma cyclic guanosine monophosphate was also raised in untreated patients. Elevated circulating levels of ANP may play a part in the haemodynamic changes of hyperthyroidism.

Topics: Adult; Atrial Natriuretic Factor; Carbimazole; Cyclic GMP; Humans; Hyperthyroidism; Middle Aged; Propylthiouracil; Thyrotoxicosis

Topics: Atrial Natriuretic Factor; Humans; Thyrotoxicosis