Normal Values
- Post-spinal surgery, it peaks at 15 ± 25 mg/L a few days after OR
- Post-stroke, it can go up to 25 ± 10 mg/L
- Post-TKA, it can go up to 155 mg/L
Interpretation
- The higher the value, the more likely to be a bacterial infection
- Non-infectious chronic inflammation, such as from smoking, uremia, or cardiac ischemia: 2 to 10 mg/L
- Mild to moderate infection such as SSTI, cystitis or bronchitis: increases to 50 to 100 mg/L within 6 hours
- Typically begins to rise after 12 to 24 hours and has a half-life of about 19 hours
| Condition | Cutoff | Sensitivity | Specificity | Notes |
|---|---|---|---|---|
| Diabetic foot osteomyelitis | >10 | 0.85 | 0.59 | near-normal by day 7 to 21 of treatment1 |
| >14 | 0.84 | 0.83 | ||
| >17 | 0.77 | 0.89 | ||
| Necrotizing SSTI | >150 | included in LRINEC score | ||
| Prosthetic joint infection | >10 | 0.96 | 0.92 | 2 |
| Spondylodiscitis | normalizes within 3 months of treatment | |||
| Septic arthritis | ≥20 | 0.92 | 3 |
Comparison to ESR
| ESR | CRP | Clinical Scenarios |
|---|---|---|
| high | low | rheumatoid arthritis, infection, low albumin, elevated creatinine |
| low | high | low albumin |
- CRP less effected by older age than ESR
Hemodialysis
- Theoretically removed with hemodialysis4, but CRP is often elevated in stable patients on hemodialysis and peritoneal dialysis5
Further Reading
- Acute Phase Reactants in Infections: Evidence- Based Review and a Guide for Clinicians. Open Forum Infect Dis. 2015;2(3):ofv098. doi: 10.1093/ofid/ofv098.
Spine
- Serum C-reactive protein levels correlate with clinical response in patients treated with antibiotics for wound infections after spinal surgery. Spine J. 2006;6(3):311-315.
- CRP better than ESR
Joints
- Serial measurement of the C-reactive protein is a poor predictor of treatment outcome in prosthetic joint infection. J Antimicrob Chemo. 2011;66(7);1590-1593.
- Although the population of patients with failure had higher CRP on average, CRP measurement was not useful for predicting failure in individual patients.
- C-Reactive Protein, Erythrocyte Sedimentation Rate and Orthopedic Implant Infection. PLoS ONE. 2010:5(2):e9358.
- ESR and CRP have poor Sn and Sp for diagnosing hardware infections
- C-reactive protein may misdiagnose prosthetic joint infections, particularly chronic and low-grade infections. International Orthopaedics. 2017.
- 1/3 of culture-positive PJIs had normal CRP and 1/4 had normal ESR.
- Most common associated organisms were coagulase-negative staphylococci and C. acnes
- Seronegative infections in hip and knee arthroplasty: periprosthetic infections with normal erythrocyte sedimentation rate and C-reactive protein level
- 4% of PJI have normal CRP and ESR
- CoNS was more common, Staph. aureus less common
Other
- Prognostic Value of Serial C-Reactive Protein Measurements in Left-Sided Native Valve Endocarditis. Arch Intern Med. 2008;168(3):302-307.
- After 1 week following starting therapy, a CRP over 122 predicts failure (OR 10)
- Utility of C-reactive protein measurements for empyema diagnosis after pneumonectomy. Annals Thoracic Surg. 1994;57(4):933-936.
- Post-operative rise or high-plateau of CRP predicted postoperative infection (empyema)
- Diagnostic Accuracy of C-reactive Protein for Intraabdominal Infections After Colorectal Resections. J Gastrointest Surg. 2009;13(9):1599-1606.
- Post-resection day 3 (or 5 or 7) CRP predicts intraabdominal infection, with Sn 82% and Sp 73% using a cutoff of 190 mg/L (normal <10)
References
- ^ Marios Michail, Edward Jude, Christos Liaskos, Spyridon Karamagiolis, Konstantinos Makrilakis, Dimitrios Dimitroulis, Othon Michail, Nicholas Tentolouris. The Performance of Serum Inflammatory Markers for the Diagnosis and Follow-up of Patients With Osteomyelitis. The International Journal of Lower Extremity Wounds. 2013;12(2):94-99. doi:10.1177/1534734613486152.
- ^ MARK J. SPANGEHL, BASSAM A. MASRI, JOHN X. OʼCONNELL, CLIVE P. DUNCAN. Prospective Analysis of Preoperative and Intraoperative Investigations for the Diagnosis of Infection at the Sites of Two Hundred and Two Revision Total Hip Arthroplasties*. The Journal of Bone & Joint Surgery. 1999;81(5):672-83. doi:10.2106/00004623-199905000-00008.
- ^ Praveen Hariharan, Christopher Kabrhel. Sensitivity of Erythrocyte Sedimentation Rate and C-reactive Protein for the Exclusion of Septic Arthritis in Emergency Department Patients. The Journal of Emergency Medicine. 2011;40(4):428-431. doi:10.1016/j.jemermed.2010.05.029.
- ^ Patrick M. Honore, David De Bels, Rachid Attou, Sebastien Redant, Kianoush Kashani. The challenge of removal of sepsis markers by continuous hemofiltration. Critical Care. 2019;23(1). doi:10.1186/s13054-019-2464-z.
- ^ Ali Borazan, Selim Aydemir, Mehmet Sert, Ahmet Yilmaz. The effects of hemodialysis and peritoneal dialysis on serum homocysteine and C‐reactive protein levels. Mediators of Inflammation. 2004;13(5-6):361-364. doi:10.1080/09629350400008786.
