A low level of the thyroid hormone triiodothyronine (T3) is a strong independent predictor of unfavorable clinical outcomes as well as preoperative depressive symptoms in patients undergoing neurosurgery for the treatment of brain tumors, indicated a recent study.

Low T3 syndrome describes the finding of low blood serum concentrations of T3, which can be accompanied by abnormal thyroxine (T4)-to-T3 conversion and high concentrations of reverse T3 without any obvious signs of thyroid disease, according to a statement issued by Journal of Neurosurgery Publishing Group. The study, published by Journal of Neurosurgery, was led by Adomas Bunevicius, MD, PhD, of both Lithuanian University of Health Sciences in Palanga, Lithuania, and the University of North Carolina at Chapel Hill.

Low T3 syndrome is highly prevalent and associated with a poor prognosis in critically ill patients. Bunevicius’s group sought to examine the association between perioperative low T3 syndrome and clinical outcomes as well as depression and anxiety symptoms in persons undergoing cancer-related brain surgery. 

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The evaluation of 90 patients (median age 55 years) demonstrated that free T3 concentrations fell postoperatively, and the proportion of persons with low T3 levels increased from 38% to 54%.

Lower preoperative and postoperative free T3 concentrations correlated with low scores on the Glasgow Outcome Scale (GOS) at discharge. Preoperative and postoperative low T3 syndrome both increased risk for unfavorable clinical outcomes (GOS scores lower than 5, with 5 representing good recovery, 1 representing death, and 4 representing moderate disability) after adjusting for several variables. Compared with patients with normal T3 concentrations, those with perioperative low T3 syndrome had a fivefold greater risk of unfavorable outcomes at discharge.

Preoperative low T3 syndrome did increase the risk for preoperative but not postoperative depressive symptoms independent of sociodemographic and clinical factors.

The researchers concluded that diagnosis and preoperative management of low T3 syndrome should be considered for persons undergoing neurosurgery for the treatment of brain tumors.