From the Guidelines
Lupus disease activity is typically assessed using a combination of laboratory tests, including complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complement levels (C3 and C4), anti-double stranded DNA (anti-dsDNA) antibodies, and urinalysis. These tests help to detect cytopenias, inflammation, and kidney involvement, which are common manifestations of lupus. Additional useful tests include comprehensive metabolic panel to assess organ function, anti-C1q antibodies which correlate with lupus nephritis, and anti-nucleosome antibodies 1. Serum albumin levels may decrease during active disease, while anti-Smith and anti-Ro/La antibodies help with diagnosis but don't typically fluctuate with disease activity.
Some key points to consider when assessing lupus disease activity include:
- The use of anti-dsDNA antibodies as a marker of disease activity, although their determination still lacks proper standardization 1
- The importance of monitoring complement levels, such as C3 and C4, which typically decrease during active disease 1
- The role of anti-C1q antibodies in lupus nephritis and their potential use as a disease-activity biomarker 1
- The need for regular monitoring of disease activity, with frequency determined by disease severity, treatment regimen, and clinical status 1
It is essential to note that the pattern of abnormalities across multiple tests provides more valuable information than any single test, as lupus affects multiple organ systems differently in each patient. Therefore, a comprehensive approach to assessing lupus disease activity is crucial for effective management and treatment. Regular monitoring of these laboratory tests, along with clinical evaluation, is necessary to assess disease activity and adjust treatment accordingly 1.
From the Research
Lupus Disease Activity Labs
The following labs are used to assess lupus disease activity:
- Erythrocyte sedimentation rate (ESR) 2, 3, 4, 5
- Complete blood count (CBC) 2
- Complement levels (C3, C4) 2, 3, 4
- Anti-dsDNA antibody levels 2, 3, 4
- C-reactive protein (CRP) 5, 6
- High-sensitivity C-reactive protein (hsCRP) 6
Correlation with Disease Activity
These labs have been shown to correlate with disease activity in lupus patients:
- ESR has been found to have a high correlation with disease activity, with higher levels indicating more active disease 2, 3, 4
- CBC results, such as hemoglobin levels, have also been found to correlate with disease activity 2
- Complement levels, such as C3 and C4, have been found to be lower in patients with active disease 2, 3, 4
- Anti-dsDNA antibody levels have been found to be higher in patients with active disease 2, 3, 4
- CRP and hsCRP levels have been found to be lower in patients with disease flare compared to those with active infection 5, 6
Diagnostic Value
These labs can be used to differentiate between disease flare and infection in lupus patients:
- ESR and CRP levels can be used to distinguish between disease flare and infection, with higher levels indicating infection 4, 5, 6
- hsCRP levels have been found to be significantly higher in patients with pulmonary involvement than without 6
- A cut-off of above 5-6 mg/dl for hsCRP has been found to correlate with infection with a specificity of 80-84% 6