What is the management approach for elevated postoperative C-Reactive Protein (CRP) levels?

From the Guidelines

Elevated postoperative C-Reactive Protein (CRP) levels should be managed by assessing for signs of infection or other inflammatory processes and ordering additional diagnostic tests, with the goal of identifying and treating the underlying cause, as supported by the most recent study from 2023 1. The management approach for elevated postoperative CRP levels involves a systematic evaluation to determine the underlying cause of the elevation. This includes:

• Assessing for signs of infection or other inflammatory processes through a thorough clinical examination, including vital signs, wound inspection, and system-specific evaluations.
• Ordering additional diagnostic tests, such as complete blood count with differential, blood cultures, wound cultures if appropriate, and imaging studies targeted to suspected sources of inflammation.
• Using serial CRP measurements to track trends, as persistently rising or non-declining CRP levels suggest ongoing inflammation requiring intervention.
• Initiating appropriate antimicrobial therapy for confirmed infections, based on likely pathogens and local resistance patterns, and adjusting based on culture results.
• Managing non-infectious causes of elevated CRP, such as tissue trauma from surgery, myocardial infarction, or pulmonary embolism, according to their specific protocols.
• Providing supportive care, including adequate pain control, hydration, and nutritional support. The approach is justified by CRP's role as an acute phase reactant produced by the liver in response to IL-6 and other inflammatory cytokines, making it a sensitive but non-specific marker of inflammation that requires clinical correlation for proper interpretation and management, as noted in the study from 2020 1. Key points to consider in the management of elevated postoperative CRP levels include:
• CRP typically peaks 48-72 hours after surgery and should gradually decline thereafter; persistent elevation beyond 3-5 days warrants further investigation.
• The use of alpha-defensin laboratory tests has been described for the diagnosis of periprosthetic joint infection, with high accuracy and sensitivity, as reported in the study from 2023 1.
• The American Academy of Orthopaedic Surgeons (AAOS) guidelines strongly recommend the use of ESR, CRP, and serum interleukin-6 testing for patients being assessed for peri-prosthetic joint infection, as mentioned in the study from 2023 1.

From the Research

Postoperative CRP Management

• The management approach for elevated postoperative C-Reactive Protein (CRP) levels involves monitoring CRP levels to diagnose and manage postoperative complications, as CRP is an acute-phase protein used clinically to diagnose infectious and inflammatory disease and monitor response to treatment 2.
• CRP levels typically peak at postoperative days two or three and then fall, but in patients with co-morbidity, the peak CRP is higher and occurs later 2.
• The use of CRP as a tool to screen for infection is limited in the first 2 or 3 days post-operatively, but it has a role in diagnosis of infection after this period and in monitoring response to treatment 2.

CRP Kinetics After Major Surgery

• CRP levels increase in the first week after major surgery, but to a much larger extent in infected than in noninfected patients 3.
• Persistently high CRP levels after postoperative day 4, especially when >100 mg/L, suggest the presence of a postoperative infection 3.
• A step-up diagnosis plan using CRP and CT-scan imaging can be effective in detecting postoperative complications following major abdominal surgery 4.

Causes of Elevated CRP Levels

• Elevated CRP levels after surgery can have various causes, including postoperative infections, cardiovascular problems, gastrointestinal problems, urologic problems, respiratory problems, and unknown origins 5.
• It is essential to perform a work-up for prosthetic joint infections and evaluate noninfectious causes and infection of other sites, in addition to periprosthetic infection 5.
• CRP measurement can be used as a preoperative marker for risk stratification, and CRP is reported as an independent fracture-risk-factor 6.

Clinical Utility of CRP Testing

• CRP testing can be helpful in diagnosis and monitoring of infections, especially for detection of early postoperative infection 6.
• CRP is a basic parameter for inflammation and is more significant and common than WBC or ESR in orthopaedic surgery 6.
• However, CRP is only a laboratory parameter and must always be correlated with clinical signs of infection 6.