From the Guidelines
Yes, both erythrocyte sedimentation rate (ESR or sed rate) and C-reactive protein (CRP) can be elevated in systemic lupus erythematosus (SLE), but CRP elevation is more variable and often suggests an underlying infection or specific lupus manifestations. According to the most recent evidence available, ESR is more consistently elevated in active lupus, often showing significant increases during disease flares 1. However, the significance of CRP in SLE remains controversial, with many authors reporting that patients with SLE rarely have elevated CRP levels, and a significant increase often suggests a superimposed infection, especially with very high values (>50 mg/litre) 1. In terms of predictors of poor immunogenicity, high erythrocyte sedimentation rate (ESR) has been found to be a predictor, differing between poor and good responders in a statistically significant fashion 1. Key points to consider when interpreting ESR and CRP in SLE patients include:
- ESR is more consistently elevated in active lupus
- CRP elevation is more variable and may suggest an underlying infection or specific lupus manifestations
- High ESR is a predictor of poor immunogenicity
- Both ESR and CRP should be interpreted alongside other clinical and laboratory findings to monitor disease activity and response to treatment. It's also important to note that neither ESR nor CRP is specific to SLE, and their elevation can occur in various other conditions, making it essential to consider the overall clinical context when interpreting these markers 1.
From the Research
Sed Rate and CRP in SLE Lupus
- Sed rate (erythrocyte sedimentation rate, ESR) and CRP (C-reactive protein) can be elevated in systemic lupus erythematosus (SLE) flare and infection, making it challenging to distinguish between the two conditions 2, 3, 4.
- ESR levels are often elevated in SLE patients, regardless of the presence of infection or flare, while CRP levels tend to be lower in SLE flares compared to infections 3, 5, 4.
- The ratio of ESR to CRP may be useful in distinguishing between infection and flare in SLE patients presenting with fever, with a higher ratio indicating a higher likelihood of flare 2.
- High-sensitivity CRP (hsCRP) levels can be used to predict active infection in SLE patients, with a cut-off value of above 5-6 mg/dl indicating infection with high specificity 3.
- CRP levels can also be elevated in SLE patients with certain clinical manifestations, such as arthritis, while complement components like C3 and C4 tend to be lower in patients with active nephritis 6.
Clinical Implications
- Measuring CRP and ESR can be helpful in differentiating between infection and relapse in SLE patients, but only under certain conditions, such as the absence of serositis 5.
- ESR remains a useful biomarker for SLE activity assessment, with levels up to 25-30 mm/h proposed as an upper limit of the normal range 4.
- CRP values greater than 10 mg/l may be indicative of severe flares, while higher CRP levels above 50-60 mg/l may be associated with infection, especially in the absence of serositis or arthritis 4.