The pathophysiology of the adrenal insufficiency of patients with critical diseases remains unclear. In a prior exploratory study investigating patients with exacerbation of chronic obstructive pulmonary disease (COPD), the investigators demonstrated a highly significant correlation between the expression level of Defensin-alpha 4 (DEFA4) mRNA in blood and the adrenal function assessed via low-dose ACTH tests. The aim of this prospective study is to demonstrate that DEFA4 measured both at the mRNA level (RT-PCR) and at the protein level (Western blot/Elisa) is a reliable biomarker for the prediction of adrenal insufficiency in inflammatory lung diseases (patients with COPD and pneumonia).