The goals of testing are to diagnose OA, to distinguish it from other forms of arthritis and causes of joint pain and stiffness, and to monitor the side effects of various Treatment.
There is no specific laboratory test to diagnose OA. It is diagnosed by a doctor using a person's medical history, a physical exam, X-rays, and in some cases with an examination of synovial fluid from an affected joint. Tests that may be ordered to rule out other conditions and to evaluate the person's health include:
- Rheumatoid factor (RF) and Cyclic Citrullinated Peptide Antibody (CCP) – to help diagnose rheumatoid arthritis (RA) and differentiate it from osteoarthritis.
- Synovial fluid analysis – to look for signs of joint infection and to detect monosodium urate (uric acid) crystals (that could indicate gout) or calcium pyrophosphate crystals that may contribute to joint damage in osteoarthritis.
- Erythrocyte sedimentation rate (sed rate or ESR) – to detect inflammation in the body; ESR will be increased in RA but not in osteoarthritis.
- C-reactive protein test (CRP) – to detect inflammation and test for the activity of the disease; it may be used to help differentiate osteoarthritis and RA. An increased level of CRP occurs in RA but not in osteoarthritis.
- Complete Blood Count (CBC) – to help evaluate the person's red and white blood cells and hemoglobin; it may be ordered to monitor the side effects of some OA treatments.
- Comprehensive Metabolic Panel (CMP) – to help evaluate and monitor the person's kidney and liver function.
- X-rays of the affected joints may show loss of cartilage, bone damage, bone spurs, and narrowing of the joint space but will frequently not show significant changes early in the disease.
- MRI (magnetic resonance imaging) – may also be used to examine affected joints.