ESR vs CRP testing for acute phase inflammation

WHY: Erythrocyte sedimentation rate (ESR) is the rate at which erythrocytes fall through plasma. ESR depends on the concentration of fibrinogen, and is an indirect measure of this concentration. It is influenced by the shape, size, and number of erythrocytes, as well as by other plasma components, such as immunoglobulins. This may result in inaccuracy and error. C-reactive protein (CRP) was discovered in 1930 and received this name because it reacted with the C-polysaccharide of pneumococcus in the acute phase of pneumococcal pneumonia. CRP measurement is a direct determination of acute phase proteins and, in the presence of inflammatory conditions, its serum levels change rapidly and its variation is wider than that of ESR. In the first 24 hours of a disease process, the CRP will be elevated, while the ESR may be normal. If the source of inflammation is removed, the CRP will return to normal within a day or so, while the ESR will remain elevated for several days until excess fibrinogen is removed from the serum. CRP is therefore a more sensitive and specific reflection of the acute phase of inflammation than is the ESR. The preferred use of CRP over ESR is a Choosing Wisely recommendation from the American Society for Clinical Pathology.

WHAT: Implement a systems-based project to reduce the inappropriate use of ESR testing. Project goals are to support evidence-based practices, standardize laboratory policies, and improve lab stewardship.

HOW: Multimodal approach to include three components:

• Education (HVC web site info, poster)

• Audit and feedback (HVC teams)

• Clinical decision support algorithm

  • Require clinician to designate an indication for ESR:

    • Giant cell arteritis

    • Polymyalgia rheumatica

    • Rheumatoid arthritis

    • Systemic Lupus Erythematosus

    • Prosthetic joint infection

    • Osteomyelitis

    • Pediatric inflammatory bowel disease

    • Hodgkins Risk Assessment