Thyroid Research Thyroid Research Archive Nonthyroidal Illness

Low serum triiodothyronine concentrations are predictor of mortality in patients with heart failure

(March 2005)

The background of the study. Serum triiodothyronine (T3) concentrations are low in many patients with nonthyroidal illness, due to a decrease in the conversion of thyroxine (T4) to T3 in many tissues. In this study, the prognostic value of measurements of serum T3 in patients with chronic heart failure was determined.

How the study was done. The study subjects were 281 patients hospitalized for treatment of chronic heart failure. All the patients had been treated for heart failure for at least one month; they were hospitalized because of increasing symptoms or decreasing cardiac function. Serum total and free T3 and total and free T4 were measured and echocardiography was performed to determine left ventricular ejection fraction soon after hospitalization. The mean duration of follow-up was 12 months. Follow-up information was obtained from the patient’s records and from death certificates.

The results of the study. During follow-up, 23 of the patients died. The patients who died were older, weighed less, had poorer cardiac function, and had lower serum total and free T3 concentrations, but similar serum total and free T4 concentrations, as compared with the patients who survived.

The mortality rate among the 127 patients with fairly good cardiac function (left ventricular ejection fraction, >20 percent) and a serum total T3 concentration >78 ng/dl (1.2 nmol/L) was 10 percent, and it was 39 percent in the 25 patients with poor cardiac function (ejection fraction, ≤20 percent) and a serum total T3 concentration ≤78 ng/dl (1.2 nmol/L). The rate was intermediate in the other 129 patients.

The conclusions of the study. A low serum total T3 concentration predicts mortality in patients with chronic heart failure.

The original article. Pingitore A, Landi P, Taddei MC, Ripoli A, L’Abbate A, Iervasi G. Triiodothyronine levels for risk stratification of patients with chronic heart failure. Am J Med 2005;118:132-6.