OBJECTIVES: During the 2009 influenza A H1N1 pandemic, it became difficult to differentiate viral infections from other conditions in patients admitted to the intensive care unit. We sought to evaluate the behavior and diagnostic utility of procalcitonin, C-reactive protein and four other molecules in patients with suspected 2009 Influenza A H1N1 infection. METHODS: The serum levels of procalcitonin, C-reactive protein, tumor necrosis factor α, interferon γ, interleukin 1β, and interleukin 10 were tested on admission and on days 3, 5, […]