Objectives: The long pentraxin PTX3 is a promising marker of disease severity in severely ill patients. In order to identify patients warranting critical care as quickly as possible, we investigated the value of PTX3 as a biomarker for disease severity in patients presenting with fever at the emergency department. Methods: Levels of PTX3 were measured in 211 febrile patients at the emergency and the levels were linked to markers of disease severity including admittance to a special care unit, bloodstream infection and congestive heart failure. Results: In comparison to median baseline levels of 2.30 ng/ml (interquartile range 1.66-3.67 ng/ml), levels of PTX3 were significantly elevated in patients admitted to the intensive/medium care unit ...