How should we investigate CUO (C-Reactive Protein elevation of Unknown Origin)? A case-based discussion of infective endocarditis in an octogenarian

Infective endocarditis and other chronic infections may cause diagnostic difficulties, regardless of age. The likelihood of an atypical presentation of chronic infection probably increases with age. Serum CRP may be a useful guide to the presence of underlying infection and its resolution in older people. The term CUO (CRP elevation of unknown origin) may have a place in triggering further investigation for the presence of infection or other pathology.