Laboratory Tests for Inflammation in General Adult Population
Order high-sensitivity C-reactive protein (hs-CRP) as your primary inflammatory marker, measured twice (optimally 2 weeks apart) and averaged, as it has superior analytic characteristics compared to all other inflammatory markers. 1
Primary Inflammatory Marker: hs-CRP
hs-CRP is the definitive choice among all inflammatory markers based on analyte stability, assay precision, accuracy, commercial availability, and standardization capabilities. 1 The American Heart Association specifically endorses this as the preferred inflammatory marker over alternatives. 2, 1
How to Order hs-CRP Correctly:
- Obtain two measurements (either fasting or nonfasting), optimally 2 weeks apart, and average the results to reduce within-individual variability 1
- Test only metabolically stable patients without obvious inflammatory or infectious conditions 1
- Report results in mg/L, expressed to 1 decimal point 1
Interpreting hs-CRP Results:
- Low risk: <1.0 mg/L 1
- Average risk: 1.0-3.0 mg/L 1
- High risk: >3.0 mg/L (represents 2-fold increase in relative risk compared to low-risk tertile) 1
- If hs-CRP ≥10 mg/L: Search for obvious sources of infection or inflammation, discard that result, and repeat testing in 2 weeks 1
Additional Basic Laboratory Tests
Complete blood count (CBC) provides white blood cell count as a general inflammatory indicator, though it lacks specificity for distinguishing bacterial versus viral infections. 1 Importantly, up to 75% of patients with prolonged inflammatory conditions have normal white blood cell counts, so normal WBC does not exclude significant inflammation. 3
Erythrocyte sedimentation rate (ESR) can be measured, though approximately 40% of patients with inflammatory conditions like rheumatoid arthritis have a normal ESR despite active disease. 4 This highlights that ESR cannot serve as a gold standard for all patients. 4
Critical Pitfalls to Avoid
Do not order alternative inflammatory markers such as serum amyloid A, soluble adhesion molecules, or cytokines, as they lack standardization, commercial availability, or require frozen samples that limit clinical use. 1
Do not rely on a single hs-CRP measurement due to within-individual variability—always obtain two measurements and average them. 1
Do not use hs-CRP for monitoring therapy response, as the role of inflammatory markers in treatment monitoring has not been established. 1
Do not interpret elevated inflammatory markers in isolation—other acute inflammatory conditions (inflammatory bowel disease, rheumatoid arthritis, chronic alcoholism) can cause mildly to moderately increased levels. 1
Do not assume normal inflammatory markers exclude disease—more than 30-40% of patients with inflammatory conditions like rheumatoid arthritis have negative or normal inflammatory markers despite active disease. 4
Context-Specific Patterns
When Intestinal Inflammation is Suspected:
- Fecal calprotectin (preferred) or lactoferrin has higher sensitivity and specificity than serum markers for detecting intestinal inflammation 1
- CRP should be assessed, though patients may have normal CRP despite active intestinal disease 2, 1
When Cardiac Inflammation is Suspected:
- Troponin and creatine kinase elevation indicates myocyte necrosis in myocardial inflammation 2
- Serum markers of inflammation are not very sensitive for myocarditis 2
When Bone/Joint Inflammation is Suspected:
- ESR and CRP are usually very elevated in immune checkpoint inhibitor-induced arthritis 2
- Autoantibodies (ANA, RF, anti-CCP) should be evaluated 2
- Alkaline phosphatase, calcium, 25-hydroxy-vitamin D, parathyroid hormone, and phosphate for bone-related inflammation 2