Plasma fT3 levels are considered to be a reliable indicator of the severity of disease in patients with acute respiratory failure in COPD (8), and low serum fT3 and fT4 concentrations increase the morbidity and mortality of patients with respiratory failure on invasive mechanical ventilation, suggesting that thyroid hormone levels may influence the prognosis of AECOPD (9). The gene discussed is TG; the disease is respiratory failure.