Do thyroid function tests independently predict survival in the critically ill?

We studied the ability of thyroid function tests to predict hospital survival in 116 critically ill patients and compared the results with independent predictions of survival made by critical care physicians. Eleven patients (9.5%) had clinically unsuspected hypothyroidism and were less likely to survive (p = 0.03). In patients critically ill with nonthyroidal disease, low T3, low FT3I, low T4, low FT4I, high TSH, and high T3U levels each showed significant correlation with nonsurvival (all p less than 0.02). Of these, however, only low T3 (p less than 0.001) and high TSH (p = 0.016) showed significant independent prediction of nonsurvival, and only low T3 (p = 0.011) added any significant independent prediction of nonsurvival beyond that made clinically by the group of critical care physicians.