Investigations involved in diagnosing rheumatic arthritis

1. Rheumatic Arthritis
INVESTIGATIONS

2. CRITERIA
FOR
DIAGNOSIS
OF
RHEUMATIC
ARTHRITIS
 Morning stiffness (>1hr)
 Arthritis of 3 or more joint areas
 Arthritis of hand joints
 Symmetrical arthritis
 Rheumatoid nodules
 Rheumatoid factor (serology)
 Radiological changes
 Duration ≥6 weeks

3. RHEUMATOID
FACTOR
• Not specific since its present in other diseases where Abs are
directed against Fc portion of other Abs.
• TB, Hepatitis, SLE, Mononucleosis, Bacterial endocarditis, Malaria,
Cirrhosis

4. ROSE
WAALER
TEST
 Sheep’s RBC is coated with gamma
globulin, agglutinates in the presence of
patient serum
 The RF attach to the immunoglobulin in
RBC
 Agglutination

5. ANTI-
NUCLEAR
ANTIBODY
(ANA)
 Test for presence of antibodies formed
against constituents of nucleus (e.g.
nucleus, histoproteins)
 20% of patients with rheumatic arthritis
are ANA positive

6. ANTI-
CITULLINATED
PEPTIDE
ANTIBODIES
 Specificity is high
 Enzyme linked immunosorbent assays (ELISA) for Abs against
cyclic citrullinated peptides may be present prior appearance of
symptoms of RA strong relo with smoking & shared epitope.

7. LATEX
FIXATION
TEST
 Coated polystyrene particles are used.
 Uses the same principle as ‘rose-waaler test’:
 The latex particles suspended in a solution of
pooled gamma globulin (substitutes
sensitized sheep cells)
 70% of patients are sero positive i.e. increased
RF levels
 30% are sero negatives:
 May be sero negative at first & become sero
(+)ve later.

8. 1. X-ray: views of hands, wrist, elbow, hip, knees,
shoulders & cervical spine-when indicated
 Changes to look for:
 Soft tissue swelling
 Narrowing of joint space: implies loss of articular
cartilage within joint which accounts for normal
joint space appearance on x-ray.
 Joint erosion
 Juxtar articular osteoporosis
2. Ultrasound & MRI-detection of early erosion

9. ESR
 Males: 3-10mm in first hour
 Females: 5-15mm in first hour
 Tube of patient anti-coagulated blood is observed
for setting out of erythrocytes
 Systemic inflammation alter serum proteins &
hence serum viscosity causing RBCs to settle out
more rapidly than normally
 The higher the viscosity, the higher the disease
activity.

10. FBC
 Anemia of RA is that of chronic disease: normocytic
normochromic.
 Severity correlates with disease activity
 Serum ferritin is usually high while levels of transferrin
& iron are low
 Iron absorption is reduced, & release of iron from
reticuloendothelial cells is impaired
 Some patient with RA exhibit IDA
 Bone marrow iron availability reduced tremendously
due to reduced iron release by mononuclear phagocytic
system.

11. RF
TITRE
 The higher the rheumatic factor titre the
more likely is to have extra-articular
features
 Does not correlate with activity of arthritis