Fever can be a symptom of a cold, or the warning sign of a serious illness. If the fever lasts longer than three weeks or recurs repeatedly with no apparent cause, medical practitioners refer to it as ‘fever of unknown origin’. Increased inflammation levels can also have an unknown origin. In both cases one thing is clear: the cause must be identified. Since these symptoms could have more serious causes, such as autoimmune diseases, infections or even tumours, time is of the essence in their diagnosis. An interdisciplinary team of physicians from the Department of Medicine 3 – Rheumatology and Immunology and the Department of Nuclear Medicine at Universitätsklinikum Erlangen has now developed a strategy for faster diagnosis. This new procedure has been published in the specialist international journal “Annals of the Rheumatic Diseases” (2016; 75: 158-159).