Diagnosis and treatment of low T3 syndrome in neurocritical patients

What is known and objective: Low levels of serum triiodothyronine (T3) are a strong predictor of mortality and poor prognosis in critical care patients. Few reports, however, have focused on neurocritical patients. The application of hormone replacement therapy (HRT) in the treatment of neurocritical patients with low T3 syndrome remains controversial. We studied the role of low T3 state as a predictor of outcomes in neurocritical patients and examined the effect of HRT on prognosis.

Methods: A retrospective analysis was performed on the data of 32 neurocritical patients with low T3 syndrome who were admitted to the neuro-intensive care unit of Peking Union Medical College Hospital between January 2012 and October 2018. While 18/32 (56.25%) patients received HRT (HRT group; n = 18), 14/32 (43.75%) patients did not receive HRT (non-HRT group; n = 14). Patients were followed up for periods ranging from 3 months to 72 months. Baseline clinical and laboratory data were compared between the two groups using Mann-Whitney U tests or the t tests. Overall survival was assessed by Kaplan-Meier curve and compared by log-rank tests. Univariate and multivariate regression analyses were performed to identify the factors associated with prognosis and estimate the effect of HRT. We also assessed the influence of HRT on final neurological function, using the Glasgow Coma Scale (GCS) and the Glasgow Outcome Scale (GOS) scores.

Results and discussion: The neurocritical events in our cohort included post-operative complications (n = 18), traumatic brain injury (n = 8) and spontaneous intracerebral haemorrhage (n = 6). Mean GCS score in the cohort was 6.41 (6.44 ± 3.14 in HRT group vs 6.36 ± 2.06 in non-HRT group). A total of 15/32 (46.87%) deaths were recorded (7 in the HRT group, 8 in the non-HRT group). In the HRT group, 15 patients underwent repeat thyroid function tests after completion of HRT; the low T3 situation was corrected in only 5/15 (33.3%) patients. Overall survival was significantly shorter in the non-HRT group than in the HRT group (16.45 months vs 47.47 months; P = .034). In univariate regression analysis, the HRT group has the lower mortality risk than the non-HRT group (HR = 0.301, 95% Cl: 0.094-0.964; P = .043). However, multivariate regression analysis showed no significant difference in mortality risk between the two groups (HR = 0.340 95% CI: 0.099-1.172; P = .087). There was no significant difference in effects of HRT on the short- and long-term neurological function between the groups.

What is new and conclusion: Low T3 syndrome may influence the prognosis of neurocritical patients, attention should be paid to the changes in serum T3 levels during treatment. Although it is unclear to what extent HRT can improve the short or long-term outcomes of neurological function, it can significantly improve the survival rates of neurocritical patients.