Study of Thyroid Functions in critically ill Patients admitted in Medical Intensive Care Unit and its Correlation with Critical Care Scoring Acute Physiology and Chronic Health Evaluation III

ABSTRACT

Background: Thyroid hormones have a crucial role in adapting the metabolic functions during stress and critical illness. Patients who are critically ill may have profound changes in thyroid hormone metabolism. Non-thyroidal Illness Syndrome (NTIS) is one among them, in which there is marked abnormality seen in the thyroid hormone levels. Hence this study is to understand the alterations of the thyroid function tests (TFTs) encountered in critically ill patients admitted in medical intensive care unit (MICU) without primary thyroid disease and to correlate with the severity of Acute Physiology and Chronic Health Evaluation (APACHE III) scoring. Methods: The study was conducted on 100 critically ill patients with no previous thyroid disorders, admitted in MICU in the Department of General Medicine in a tertiary care hospital between September 2017 and August 2019 who fulfilled the inclusion and exclusion criteria. Results: Out of 100 critically ill patients the abnormal thyroid function prevalence was seen in 78% patients. The most common abnormality seen in our study was low total triiodothyronine (TT3) (61%) followed by low free triiodothyronine (FT3) (36%), low total thyroxine (TT4) (29%), high thyroid-stimulating hormone (TSH) (18%), and low free thyroxine (FT4) (12%). Low TT3, TT4, and FT3 values had a significant correlation with increasing critical severity score of APACHE III with a p value which was statistically significant (p < 0.05). Conclusions: With increase in severity of critical illness assessed by APACHE III, TFT, that is, TT3, TT4, and FT3 levels were decreasing, suggestive of increasing non-thyroidal illness in critically ill patients.