2nd-order laboratory parameters – depending on the results of the history, physical examination, and obligatory laboratory parameters – for differential diagnostic clarification.
- Small blood count
- Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
- Renal parameters – urea, creatinine, if necessary cystatin C or creatinine clearance.
- Uric acid
- Joint punctate
- Rheumatoid diagnostics – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate); rheumatoid factor (RF), CCP-AK (cyclic citrulline peptide antibodies), ANA (antinuclear antibodies).
- Blood culture or blood cultures – if bacteremia is suspected.
