2nd order laboratory parameters – depending on the results of the history, physical examination, and obligatory laboratory parameters – for differential diagnostic clarification.
- Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
- Microbiological examination – if infectious diseases are suspected.
- Uric acid – if gout/hyperuricemia is suspected.
- Parathyroid hormone (PTH) – if hyperparathyroidism is suspected.
- Cyclic citrulline peptide antibodies (CCP-AK) – for suspected rheumatoid arthritis (chronic polyarthritis).