FREQUENCY OF ABNORMALITIES OF THYROID FUNCTION TESTS IN PATIENTS PRESENTING WITH ACUTE MEDICAL ILLNESS

Background: Euthyroid Sick Syndrome (ESS), also known as non-thyroidal illness syndrome, refers to transient alterations in thyroid hormone levels in patients with acute systemic illness, without intrinsic thyroid disease. It is commonly observed in critically ill individuals and is believed to be an adaptive physiological response to systemic stress. Accurate interpretation of thyroid function tests (TFTs) in such settings is crucial, as misinterpretation may lead to unnecessary interventions or misdiagnosis of true thyroid dysfunction. Objective: To determine the frequency of abnormalities in thyroid function tests, specifically the occurrence of Euthyroid Sick Syndrome, in patients presenting with acute medical illness. Methods: This comparative cross-sectional study was conducted at the Department of Medicine, Combined Military Hospital, Jhelum, from January to June 2024. A total of 220 patients admitted to the Medical Intensive Care Unit (ICU) for non-thyroidal illnesses were enrolled using non-probability consecutive sampling. Thyroid function was assessed by measuring serum T3, T4, and TSH levels. Patients with known thyroid disorders, pregnant or lactating women, and those with autoimmune diseases were excluded. Results were analyzed using SPSS version 24.0, with frequencies, percentages, medians, and interquartile ranges (IQRs) calculated for relevant variables. Results: Of the 220 patients, 140 (63.6%) were male and 80 (36.4%) female. The overall median age was 60 years (IQR 18). The median serum levels were: T3 – 1.8 nmol/L (IQR 1.1), T4 – 15 pmol/L (IQR 9), and TSH – 3.6 mIU/L (IQR 1.3). Based on the diagnostic criterion of low T3 with normal T4 and TSH, 60 patients (27.3%) were found to have ESS. Conclusion: Euthyroid Sick Syndrome is a frequent and clinically relevant cause of thyroid function test abnormalities in critically ill patients. Its recognition is essential for avoiding misdiagnosis and inappropriate treatment in ICU settings.