SICK EUTHYROID SYNDROME IN PATIENTS WITH MODERATE-TO-SEVERE CHRONIC HEART-FAILURE

Background Changes in peripheral thyroid hormone concentration and met abolism can occur in euthyroid patients suffering from severe non-thyr oidal illnesses. Recently, sick euthyroid syndrome has been reported i n patients suffering from advanced heart failure. Aim This study was t o evaluate prospectively the presence and pathophysiological implicati ons of sick euthyroid syndrome in moderate-to-severe chronic heart fai lure patients. Methods The study population were 199 chronic heart fai lure patients admitted over a 2-year period to our heart failure unit for assessment of cardiac transplantation. They were closely followed up with clinical and instrumental examinations (including clinical, ho rmonal, nutritional and cardiac function evaluations). Sick euthyroid syndrome was defined as a serum total triiodothyronine value of less t han the lowest normal limit (<1.23 nmol . l(-1)) in the presence of a normal serum thyroid stimulating hormone concentration. Results Sick e uthyroid syndrome was found in 36/199 patients (18%). According to the New York Heart Association (NYHA) classification of severity of heart failure, sick euthyroid syndrome patients appear in higher NYHA class es (31% of classes III and IV, vs 7% of class I and II). Such patients also weigh less and are more frequently malnourished. Alterations in cardiac index, ventricular filling pressures, functional impairment, a nd the liver function parameters, were more significant in sick euthyr oid syndrome than in non-sick euthyroid syndrome patients. Serum norep inephrine and atrial natriuretic factor were significantly higher, and insulin significantly lower in the sick euthyroid syndrome group. Dur ing follow-up, deaths were significantly more frequent in sick euthyro id syndrome patients (13/27, 48%) than in non-sick euthyroid syndrome (30/141, 21%; P<0.005). In six sick euthyroid syndrome patients who un derwent heart transplantation, mean total triiodothyronine values incr eased from 0.9 +/- 0.1 before to 1.96 +/- 0.3 nmol.l(-1) post-transpla ntation (P<0.05). Conclusions In a large and representative population of patients with moderate-to-severe heart failure, sick euthyroid syn drome shows a prevalence of 18%. Its occurrence was related to the deg ree of functional cardiac impairment, but was not an independent negat ive prognostic factor. Preliminary results indicate that heart transpl antation is associated with reversibility of sick euthyroid syndrome.