Low T3 syndrome in patients with major trauma - Phenomenon or important pathogenic factor?

Backgroud: Many nonthyroidal illnesses, such as major trauma, severe burn i njury, sepsis or immune deficiency are associated with a reduced T3 concent ration without increased serum TSH secretion. The pathopysiologic meaning o f this phenomenon was controversely discussed since its investigation 20 ye ars ago. The identification of the Type I 5-iodthyronine-deiodinase as a se lenoenzyme brought many new aspects into this discussion. Patients and Methods: To investigate the correlation of T3 blood levels and the selenium concentrations in consideration of the severity of the nonthy roidal illness 20 patients with major trauma where included in this study. In all these patients frequently T3, T4, fT3, fT4, TSH, Se (whole blood), S e (plasma) and Glasgow-Coma-Scale (GCS), APACHE II and MOF-Score where meas ured until the 28th day of illness. Results: Five patients (20%) died during the study until the 8th day of mea surement. Survivors and nonsurvivors initial showed a low T3 and fT3 level in serum While the T3 serum concentrations of nonsurvivors remained on a lo w level the thyronine concentrations of survivors distinctly increased. The measured thyroid hormone concentrations were significantly correlated with MOF-score, APACHE IL and inversely with GCS. There was no significant corr elation between low T3/fT3 blood levels and low selenium concentrations in all observed patients. Conclusion: The selenium deficiency in all patients with major trauma seems to be not the single cause of the low T3 syndrome. The distinctly suppress ion of TSH could be caused by the action of various cytokines such as IL-6 and TNF-alpha. Further investigations should improve the effectivity of sub stitution of selenium and/or thyroid hormones in the therapy of patients wi th severe nonthyroidal illness.