Overview: C-Reactive Protein (CRP) TestIntroduction: The C-Reactive Protein Test measures CRP to detect inflammation or infection, causing fever or joint pain. Aligned with 2023 ACR guidelines, it uses an immunoassay for high sensitivity, aiding in inflammatory screening. This test is critical for guiding diagnosis, treatment, and improving outcomes in immunology for patients with suspected inflammatory or infectious conditions.
Other Names: CRP Assay, Inflammation Marker Test.
FDA Status: Laboratory-developed test (LDT), meeting immunology standards for diagnostic accuracy.
Historical Milestone: CRP testing began in the 1930s with inflammation research. Immunoassays emerged in the 1970s, and by the 2000s, high-sensitivity assays improved accuracy.
Purpose: Diagnoses inflammation or infection, guides treatment, and monitors CRP levels in patients with fever or joint pain.
Test Parameters: 1. C-Reactive Protein
Pretest Condition: Fasting for 10-12 hours required to stabilize CRP levels. Collect serum or plasma after overnight fasting. Report symptoms like fever or joint pain, and list medications like anti-inflammatories.
Specimen: 2-5 mL serum (SST) or 2-4 mL plasma (EDTA). Centrifuge within 1 hour. Transport in a biohazard bag within 8 hours.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 7 days
Sample Stability at Frozen: 6 months
Medical History: Document fever, joint pain, or history of infections/autoimmune diseases. Include current medications, especially steroids or anti-inflammatories.
Consent: Written consent required, detailing the tests purpose, diagnostic implications, and potential need for anti-inflammatory or antibiotic therapy.
Procedural Considerations: Uses an immunoassay to measure CRP levels. Results are available in 1-2 days, enabling rapid clinical decisions.
Factors Affecting Result Accuracy: Non-fasting samples or acute infections may elevate CRP levels. Hemolysis can degrade samples.
Clinical Significance: Elevated CRP levels indicate inflammation or infection, prompting treatment. Normal levels suggest alternative diagnoses.
Specialist Consultation: Consult a rheumatologist for inflammatory results or an infectious disease specialist for infection-related cases.
Additional Supporting Tests: ESR, procalcitonin test, or blood cultures to confirm inflammation or infection.
Test Limitations: Non-specific for cause of inflammation. Results require clinical correlation.
References: ACR Inflammation Guidelines, 2023; Arthritis and Rheumatology, Crowson CS, 2022.
