COMPARISON OF THYROID-HORMONE AND CORTISOL MEASUREMENTS WITH APACHE-II AND TISS SCORING SYSTEMS AS PREDICTORS OF MORTALITY IN THE MEDICAL INTENSIVE-CARE UNIT

Thyroid and adrenal functions were evaluated in 49 consecutive critica lly ill, mechanically ventilated patients admitted to the medical inte nsive care unit (MICU) at Ben Taub General Hospital in Houston, TX. On admission, severity of illness was assessed by Acute Physiological As sessment and Chronic Health Evaluation II (APACHE II) and Therapeutic Intervention Scoring System (TISS) scores, Thyrotropin Stimulating hor mone (TSH) measured with a sensitive assay thyroxine (T4), tri-iodothy ronine (T3), T3 resin uptake, and cortisol levels were measured on the first MICU day at 8 AM, and results were assessed based on ability to predict mortality. It was shown that severe hypothyroxinemia (T4 < 3 mu g/dL) was associated with a 75% mortality as opposed to a mortality rate of 19% in patients with a T4 level of 3 mu g/dL or more (p < 0.0 1), and a high 8 AM cortisol level (> 30 mu g/mL) was associated with a 56% mortality versus 0% in patients with cortisol values less than 3 0 mu g/dL (p < 0.005), whereas a high APACHE II (> 25) score and a hig h TISS (> 25) score were only associated with a mortality of 47%, (p = 0.06) and 32% (NS), respectively, versus 21 and 20%, respectively; in patients with scores less than 25, Logistical regression analysis rev ealed that of all the variables. 8 AM cortisol level had the best pred ictive value of outcome, followed by T4 levels and T3 resin uptake lev els. Although high cortisol and low T4 levels used alone had a sensiti vity of 56 and 75% and a specificity of 100 and 80.5%, respectively, c ombined lon T4 and high cortisol levels had a sensitivity of 100% and a specificity of 81.5% in predicting mortality. Very low T4 levels, du e to severe illness, combined with high cortisol Levels (implying high physiological stress), are more sensitive predictors of mortality tha n APACHE II, TISS, cortisol levels, or T4 levels alone, or any other c ombination of predictors.