Many pathology tests are ordered unnecessarily in primary care and this can include testing for inflammatory markers. The most common examples of tests typically ordered are for erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels, with occasional requests for plasma viscosity (PV) too. Although such tests can be useful in giving some information as to a patient’s inflammatory response in certain conditions, their lack of specificity means that they are not perfect tests and interpretation is not always straightforward. In this podcast, Dr Roger Henderson looks at how inflammatory markers work, what may or may not constitute a normal reading and what to do with abnormal results.