Diagnosis of gout flare*

CPP: calcium pyrophosphate.
* Refer to the UpToDate topic on the clinical manifestations and diagnosis of acute gout, which should be used together with this algorithm, for further information. Use of imaging for diagnosis requires particular expertise in the relevant imaging techniques and their interpretation, as well as ready availability of the technology.
¶ Synovial fluid analysis should include white cell count and differential, Gram stain and culture, and crystal search under compensating polarized light microscopy.
Δ Refer to UpToDate topic review on septic arthritis or septic bursitis, depending upon the affected region. Consultation with an expert on arthrocentesis (eg, a rheumatologist or orthopedist) or an interventional radiologist is required to obtain synovial fluid for analysis if there is clinical suspicion of septic arthritis.
◊ The sensitivity of the joint fluid analysis can be improved by examination of the sediment in a centrifuged specimen. Additional approaches to consider in the event of a negative (no urate crystals seen) study during the acute attack include aspiration of a concurrently inflamed joint or aspiration of an uninflamed but previously involved joint or of a tophus if either is present, although aspiration of an uninflamed joint or tophus is less helpful in excluding an accompanying cause for the acute event.
§ Coexisting infection should be excluded based upon the synovial fluid analysis, including Gram stain and culture.
¥ The evaluation and management of patients in this group is complex. Refer to the UpToDate topic on the clinical manifestations and diagnosis of gout for additional discussion.