C-Reactive Protein (CRP) is synthesized in the liver. CRP begins to rise within 4-6 hours after stimulus from an inflammation/infection. The level doubles every eight hours and peaks at 36-50 hours.
CRP is a sensitive marker of inflammation and tissue damage. However, it has a low specificity. Conditions other than sepsis that can cause a rise in CRP levels include:
- Rheumatic diseases
- Systemic lupus erythematosus
- Systemic sclerosis
- Sjogren syndrome
- Inflammatory bowel disease
- Leukemia
- Transfusion-associated graft-vs-host disease
Once the determination has been made that sepsis is present and therapy has been initiated, CRP is useful for monitoring response to antibiotics and predicting prognosis.
CRP levels of <3 µg/mL are considered within normal range, while levels >150 µg/mL are considered positive for sepsis in a patient suspected of having sepsis.
