Gout: diagnosis and initial tests

• Fever, impaired general condition or doubt about septic arthritis: opinion or emergency department without waiting for the tests.

Laboratory tests

• Serum urate (if normal during the flare, recheck it at least 2 weeks later)
• Joint fluid examination: crystals, cytology, bacteriology (if aspiration feasible)if needednon-French guidelineAs soon as a tap is possible: testing for urate crystals is recommended in anyone with suspected gout and in any patient with undiagnosed inflammatory arthritis ^[1]; failing that, at least when the diagnosis remains uncertain ^[2].

Fasting laboratory tests, away from the attack

• Serum urate (baseline value)
• Serum creatinine with eGFR
• Fasting plasma glucose
• Lipid profile
• ASTif neededBefore starting febuxostat: the SmPC recommends liver function tests before initiation then periodically ^[5].
• ALTif neededBefore starting febuxostat: the SmPC recommends liver function tests before initiation then periodically ^[5].
• HLA-B*5801 allele testing (before allopurinol, if South-East Asian or African-American origin)if needednon-French guidelinePatients of South-East Asian (Han Chinese, Korean, Thai) or African American origin, in whom the allele, associated with severe hypersensitivity reactions to allopurinol, is more frequent ^[6].