Evaluation of Thyroid dysfunction in patients with chronic obstructive pulmonary disease in medical intensive care unit of Zagazig University Hospitals

Background: Thyroid abnormalities in some studies are frequent among patients with chronic obstructive pulmonary disease (COPD) admitted to intensive care unit with acute exacerbation especially with more severe cases. Other studies reported no significant thyroid dysfunction in those patients. Mortality was increased in COPD patients with exacerbation who got thyroid abnormalities. Aim of the work: To assess; the frequency and different patterns of thyroid dysfunction, risk factors and its correlation with thyroid abnormalities, and the impact of thyroid dysfunction on short term outcome of COPD patients with acute exacerbation admitted to Zagazig University Hospitals medical intensive care unit (MICU). Patients and Methods: This cohort study had been included 48 COPD patients with acute exacerbation determined by the Institutional Review Board (IRB); who were admitted to the MICU of Zagazig University during the period of 6 months; with exclusion of patients with known thyroid disease or under thyroxin therapy. All patients were subjected to thorough history and complete clinical examination, assessment of severity score system in the ICU unit using APACHE II score, routine laboratory investigations including complete blood count, liver function tests and kidney function tests, arterial blood gases (ABG) and Specific investigations that include assay of serum level of Thyroid Stimulating Hormone (TSH), free T3 (FT3), and free T4 (FT4). According to thyroid dysfunction, patients were classified into two groups; group I included patients with thyroid abnormalities & group II included patients with euthyroid function. Patients were followed and observed during their hospital stay until discharge (2 weeks). Results: The frequency of thyroid dysfunction in patients with COPD admitted with acute exacerbation was 25%. All patients with thyroid dysfunction in the study population had decreased FT3 level with normal FT4 and TSH (Sick euthyroid syndrome). Sick euthyroid group was characterized by significant increase in APACHE II score than the euthyroid group. FT3 and FT4 were negatively correlated with APACHE II score and partial pressure of carbon dioxide (PaCO2) while FT3 was positively correlated with partial pressure arterial oxygen (PaO2). In univariate and multivariate logistic regression analysis regarding the potential predictors of thyroid dysfunction; male sex, increased age, prolonged duration of the disease, increased hematocrit, increased blood urea, increased PaCO2, increased bicarbonate (HCO3) and decreased PaO2 were predictors of thyroid dysfunction. Relative risk of thyroid dysfunction was increased with; PaO2 < 60 mmHg, PaCO2 > 45 mmHg, HCO3 > 24 mEq/L, APACHE II score > 14; by 6.43 fold, 2.75 fold, 1.2 fold, 1.7 fold respectively. In univariate logistic regression analysis regarding the potential predictors of mortality; APACHE II score was the most independent predictors of mortality in sick euthyroid group. Relative risk of mortality in sick euthyroid group was increased by 2.1 fold than euthyroid group. Conclusion: Thyroid abnormalities are frequent among COPD patients with acute exacerbation admitted to MICU of Zagazig University Hospitals. Sick euthyroid syndrome was solely identified in those patients especially with more severe cases. Mortality was significantly increased in COPD patients with acute exacerbation who got thyroid abnormalities. Further studies are needed to assess the benefit from thyroid hormone replacement therapy on decreasing mortality in COPD patients with acute exacerbation.