How to investigate new-onset polyarthritis

Area of Science:

• Rheumatology
• Clinical Immunology
• Diagnostic Medicine

Background:

• Polyarthritis encompasses diverse conditions, including rheumatoid arthritis and metabolic disorders.
• Initial diagnosis involves differentiating inflammatory from non-inflammatory causes using inflammation markers.
• Laboratory tests are vital for diagnosing and prognosing rheumatic diseases, but results can be influenced by disease stage.

Purpose of the Study:

• To emphasize the importance of clinical differential diagnosis in selecting appropriate serological tests for polyarthritis.
• To discuss the role and limitations of various diagnostic tools in early polyarthritis detection.
• To highlight the impact of testing timing on diagnostic accuracy.

Main Methods:

• Review of laboratory markers for inflammation.
• Evaluation of serological tests, including anti-citrullinated protein antibody (ACPA), rheumatoid factor, and human leucocyte antigen (HLA) B27.
• Assessment of advanced imaging modalities: ultrasonography (USG), magnetic resonance imaging (MRI), and dual-energy computed tomography (DECT).

Main Results:

• Inflammation markers are useful but can be misleading.
• Test selection should be guided by clinical diagnosis, not broad 'arthritis panels'.
• Timing of testing significantly impacts results; synovial fluid analysis has limited utility in new-onset polyarthritis.

Conclusions:

• Strategic selection of diagnostic tests, guided by clinical presentation, is essential for accurate polyarthritis diagnosis.
• While advanced imaging shows promise, its definitive role in rheumatology requires further definition.
• Judicious use of laboratory and imaging tools improves diagnostic and prognostic accuracy in rheumatic diseases.