Pyrexia, or fever of unknown origin (PUO) is a syndrome that challenges the diagnostic skills of every physician. It is defined by frequent fevers over 38.3 degrees Celsius, persisting for 3 weeks, which have eluded diagnosis by standard baseline tests.

Dr Rohan Beresford, Advanced Trainee in infectious diseases and microbiology and Professor Iain Gosbell of the University of Western Sydney, review the condition in September's issue of the RACP's Internal Medicine Journal. In a recent case series, they write, 22% of PUO cases were auto-inflammatory, 16% were attributed to infection, 7% were neoplastic, and 4% were due to drugs or other miscellaneous causes. But over 51% of patients with PUO were left with no diagnosis at all.

On this this episode, Dr Beresford explains how to rationally investigate patients with persistent fevers and manage their anxiety through the process. He is joined by paediatrician and infectious diseases specialist Dr Philip Britton FRACP (Children's Hospital Westmead), describing some of the conditions that more likely explain PUO in children, and Dr David Spriggs FRACP (Auckland City Hospital), who provides examples of the complexity of PUO in geriatric patients.

This episode was produced by Mic Cavazzini with recording assistance from Justin Gregory. Music from Chris Zabriskie ('I Am Running with Temporary Success from a Monstrous Vacuum in Pursuit'), Jahzaar ('Gramaphone', 'Aisles') and Scott Holmes ('Close to the Distance'); photo courtesy Armle. The production manager was Anne Fredrickson.

Editorial feedback was provided by RACP Fellows Dr Bruce Foggo, Prof David Gordon, Dr Michael Herd, Dr Marion Leighton and Dr Christian Lueck.

Please visit the RACP website for a transcript embedded with citations. Fellows of the College can claim CPD credits for listening and additional reading.