αANP, AVP, and pituitary-thyroid axis in patients with congestive heart failure and acute respiratory failure

The pituitary-thyroid axis and neurohumoral activation indexes were simultaneously investigated in 16 in-patients hospitalized for cardiac heart failure (CHF), New York Heart Association (NYHA), class II-IV, and Killip clinical scale, class II-III, to evaluate their relationship with CHF morbidity and the relative prognostic value. At entry the patients were divided into two subgroups (A and B), according to the severity of CHF. Patients were further classified into two subgroups, according to the subsequent clinical course (C, poor outcome and D, improved clinical course). Blood samples were obtained every day for the radioimmunoassay measurement of plasma a-atrial natriuretic peptide (αANP), arginine vasopressin (AVP), and thyroid hormones, and the results were compared with those of 12 control subjects. At admission, αANP and 3,3′,5′-triiodothyronine (rT3) values were higher, while 3,3′,5-triiodothyronine (T3) to rT3 (T3/rT3) ratio was lower in subgroups A and B than in controls (p<0.001), respectively, and in C than in D (p<0.001), respectively, according to the prognosis. Conversely, no differences in other thyroid indexes, nor a significant correlation between αANP and either rT3 or T3/rT3 ratio were present in any of the subgroups. AVP plasma levels in subgroup A were not statistically different from those of controls, whereas they were significantly decreased in subgroups B and C (p<0.05) and D (p<0.001). In conclusion, these results indicate that in CHF the pituitary-thyroid axis is not altered, that αANP and T3/rT3 ratio are non-invasive and reliable predictors of severity and prognosis, while AVP might be affected by the different pathological processes leading to CHF or by the concomitant use of drugs.