False-positive synovial fluid alpha-defensin test in a patient with acute gout affecting a prosthetic knee

The alpha-defensin test has demonstrated promising results in studies evaluating it for the diagnosis of prosthetic joint infection. There are limited data in the literature regarding its use in patients with other inflammatory joint conditions, but a high specificity for infection has been reported. We describe a patient with a prosthetic knee joint, who had a positive alpha-defensin lateral flow assay but in whom subsequent results confirmed a diagnosis of acute gout with no evidence of infection.