Early manifestations of "sick euthyroid" syndrome in patients with compensated chronic heart failure

Background: A "sick euthyroid" syndrome occurs in patients with severe deco mpensated chronic heart failure (CHF) and other chronic illnesses and is re lated to adverse prognosis, but it has not been described in patients with compensated CHF. The aim of this study was to determine whether manifestati ons of the sick euthyroid syndrome occur in patients with compensated CHF c aused by ischemic heart disease. Methods and Results: Thyroid hormonal responses to thyrotropin-releasing ho rmone (TRH) stimulation were compared in 8 patients with New York Heart Ass ociation class I/II CHF considered secondary to ischemic heart disease and 7 control patients after serial 10-minute blood sampling over 3-hour period s. Secretory dynamics of TRH-induced thyroid-stimulating hormone (TSH) rele ase were compared by using deconvolution analysis. Changes in serum thyroxi ne (T-4), triiodothyronine (T-3), reverse T3 (rT(3)), and rT(3)/T-4 concent ration ratios were compared. Patients with CHF had lower baseline serum T-3 concentrations (P < .001), with lower maximum serum T-3 (P < .01) and high er maximum serum rT(3) (P < .05) concentrations after TRH stimulation but s imilar estimated TRH-induced TSH secretory burst amplitude, mass, and 3-hou r production rates, compared with control patients, Conclusions: Patients with compensated CHF display the derangements in thyr oid hormone metabolism of impaired peripheral conversion of T-4 and T-3 and increased production of rT(3) in the presence of normal dynamic function o f the hypothalamic-pituitary-thyroid axis, which are consistent with early manifestations of a sick euthyroid state.