Polyarticular Joint Pain – Lab findings & Conditions

This list is to be viewed only in the context of evaluation of patients with polyarticular joint pain.
| Laboratory or Imaging Tests | Condition(s) | |
| Complete Blood Count (CBC) | Anemia | Many inflammatory arthritides, especially SLE, RA, IBD and human parvovirus B19 infection |
| Polycythemia | Myeloproliferative disorder | |
| Thrombocytopenia | SLE, human parvovirus B19 infection | |
| Thrombocytosis | Acute-phase reaction, vasculitis, infection | |
| Leukopenia | SLE, RA, Felty’s syndrome, Sjogren’s syndrome, human parvovirus B19 infection Leukocytosis RA, vasculitis, reactive arthritis, infection | |
| Absolute Lymphocytosis | CLPD (polyarthritis can be one of the components of clinical manifestation) | |
| Eosinophilia | SLE, RA, IBD, sarcoidosis, dermatomyositis, scleroderma, Churg-Strauss syndrome, PAN, eosinophilic fasciitis, cholesterol emboli | |
| Chest X-Ray |
|
|
| Diffuse Fibrosis | RA, Scleroderma, Polymyositis | |
| Joint Aspiration | Growth on culture | Infection |
| Crystals | Gout, Pseudogout | |
| WBC Count | >2000/mm3 — Inflammation > 50000/mm3 — Probable infection | |
| Urinalysis | Hematuria | SLE, Wegener’s granulomatosis, PAN |
| Pyuria | Reactive polyarthritis (due to UTI) | |
| Proteinuria | SLE; Wegener’s granulomatosis, amyloidosis | |
| ECG | Atrioventricular Block | Lyme disease, neonatal lupus, ankylosing spondylitis |
| APTT/Lupus anticoagulant/APLA | Prolonged/Present | SLE, APLA Syndrome |
| Rheumatoid Factor | RA, SLE, Sjogren’s syndrome, sarcoidosis, reactive arthritis, PMR, polymyositis, psoriatic arthritis, endocarditis, chronic infections, cancer, chronic liver disease, many nonrheumatic causes | |
| Anti-CCP Antibody | RA | |
| Inflammatory markers | Infection, most inflammatory arthritides, advanced age, PMR, giant cell arteritis, cancer, anemia, pregnancy; menses | |
| Antinuclear Antibody | SLE, RA, scleroderma, Sjogren’s syndrome, vasculitis, polymyositis, medications, many nonrheumatic causes | |
| Elevated SGOT/SGPT | SLE, PAN, sarcoidosis, hemochromatosis, Sjogren’s syndrome, infectious hepatitis, polymyositis | |
| Elevated ALP | Bone metastases, Paget’s disease, osteomalacia, PMR, ankylosing spondylitis, hyperparathyroidism | |
| Elevated LDH | Autoimmune hemolytic anemia, myositis | |
| dsDNA | SLE, especially lupus nephritis | |
| Anti SS-A/Ro, Anti SS-B/La | Sjogren’s syndrome, SLE | |
| HLA-B27 | Spondyloarthropathies, reactive arthritis | |
| Elevated Uric Acid | Gout, psoriatic arthritis, Paget’s disease | |
| False-Positive VDRL | SLE, APLA Syndrome | |
| c-ANCA | Wegener’s granulomatosis | |
| Elevated Creatinine | SLE, Wegener’s granulomatosis, vasculitis | |
| Elevated Creatine Kinase (CPK) | Polymyositis, dermatomyositis, hypothyroidism | |
| Elevated Calcium | Hyperparathyroidism, cancer, sarcoidosis | |
RA: Rheumatoid Arthritis, SLE: Systemic Lupus Erythematosus, IBD: Inflammatory Bowel Disease, CLPD: Chronic Lymphoproliferative Disease, PAN: Polyarteritis Nodosa, UTI: Urinary Tract Infection, APLA: Anti Phospholipid Antibody
References:
- Alpay-Kanitez N, celik S, Bes C. Polyarthritis and its differential diagnosis. Eur J Rheumatol. 2019 Nov 11;6(4):167-73.
- Mies Richie A, Francis ML. Diagnostic approach to polyarticular joint pain. Am Fam Physician. 2003 Sep 15;68(6)1151-60.
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