Physical Examination
A physical exam is one of the first steps in diagnosing rheumatoid arthritis. During an exam, your doctor will inspect your joints for signs of swelling, warmth, tenderness, or limited range of motion. They may check your wrist, fingers, knees, and feet for abnormalities. Your doctor will also feel your lymph nodes for enlargement. The physical exam helps determine which joints may be affected.
Blood Tests
Several common blood tests are used to help diagnose rheumatoid arthritis and monitor its progression.
Rheumatoid Factor (RF) Test
The rheumatoid factor (RF) test detects antibodies that mistakenly attack proteins in your own body. Around 80% of people with established rheumatoid arthritis test positive for RF, though some RF-negative patients have the disease as well. An elevated RF level suggests rheumatoid arthritis but is not definitive on its own.
C-Reactive Protein (CRP) Test
The CRP test measures levels of C-reactive protein, a substance the liver produces in response to inflammation. CRP levels are often elevated in rheumatoid arthritis as joint inflammation rises and fall when treatment brings inflammation under control. A high CRP combined with joint symptoms may indicate rheumatoid arthritis.
Erythrocyte Sedimentation Rate (ESR) Test
The ESR test measures how fast your red blood cells settle in a tube of blood over an hour's time. Faster sedimentation may show higher levels of inflammation from conditions like rheumatoid arthritis. An elevated ESR combined with symptoms strengthens a possible diagnosis.
Anti-CCP Antibody Test
Anti-CCP stands for anti-cyclic citrullinated peptide antibody. These antibodies specifically attack modified proteins and are present in 60-80% of rheumatoid arthritis patients, sometimes even before clinical symptoms appear. The anti-CCP test is more specific to rheumatoid arthritis than the RF test.
Imaging Tests
When the physical exam and blood tests point to possible rheumatoid arthritis but are unclear, imaging scans can provide more details.
X-rays
Plain X-rays are often the first type of scan done. They can reveal signs of rheumatoid arthritis like joint space narrowing, bone erosions, subluxation (partial dislocation), and deformity changes consistent with long-standing disease. X-rays provide structural information but cannot detect early damage before bone changes appear.
Magnetic Resonance Imaging (MRI) Scans
MRI scans are more sensitive than X-rays and can detect inflammation, swelling, or damage in the soft tissues, cartilage, and bone marrow in the earliest stages before bone erosion occurs. They are helpful for assessing rheumatoid arthritis activity when blood tests are inconclusive or inconsistent with symptoms.
Ultrasound
Ultrasound uses sound waves to create images of joints and surrounding soft tissues. It can detect joint swelling, fluid buildup, thickened synovial membranes, and blood vessel proliferation associated with rheumatoid arthritis inflammation. Ultrasound is less expensive than MRI and has no radiation exposure, so it may be suitable for monitoring a patient's response to treatment over time.
Synovial Biopsy
When rheumatoid arthritis is suspected but not confirmed by other tests, a synovial biopsy of the tissue lining an affected joint may provide confirmation. During an arthroscopic procedure, a small sample of synovial membrane is taken and viewed microscopically for signs of inflammation characteristic of RA like synovial hyperplasia and immune cell infiltrates. A biopsy rules out other conditions but is reserved for unclear cases.
In Summary
No single test can definitively diagnose rheumatoid arthritis on its own. A careful physical examination combined with certain blood biomarkers, imaging studies, and potentially a synovial biopsy helps rheumatologists piece together the clinical picture and determine if signs and symptoms align with rheumatoid arthritis or another condition. Early detection allows for faster treatment to reduce joint damage and disability from this chronic autoimmune disorder.
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