Tests to Assess Disease Activity
When a person diagnosed with lupus develops new or recurring symptoms, laboratory testing of blood or urine can help determine if the symptoms are due to an increase in lupus activity.
Disease activity correlates with a rise in:
- CRP (C-reactive protein) binding
- ESR, or sedimentation rate
- Liver and kidney function tests (AST, ALT, BUN, creatinine)
- CPK (muscle enzyme)
- Urine protein or cellular casts
Disease activity also correlates with a fall in:
- CBC or complete blood count (white blood cell count, hemoglobin, platelets)
- Complement components
- Serum albumin
Putting It All Together
The interpretation of all these tests, and their relationship to symptoms, can be difficult. When a person has many symptoms and signs of lupus and has positive tests for lupus, it is easier for physicians to make a correct diagnosis and begin treatment. However it is more common for an individual to report vague, seemingly unrelated symptoms of achy joints, fever, fatigue, or pain, and to have negative or borderline test results.
Fortunately, with growing awareness of SLE, an increasing number of physicians will consider the possibility of lupus in the diagnosis. While these tests are useful only when their strengths and limitations are understood, in the hands of skilled physicians these are important tools that assist in diagnosing lupus.