Can Diverticulitis Raise C-Reactive Protein Levels?
Yes, diverticulitis consistently and significantly raises C-reactive protein (CRP) levels, and CRP is now recognized as the single most useful biomarker for both diagnosing acute diverticulitis and predicting its severity. 1
CRP as a Diagnostic Tool
CRP ≥50 mg/L is a validated diagnostic criterion for acute diverticulitis. 1 When combined with left lower quadrant tenderness and absence of vomiting, a CRP >50 mg/L achieves 97% diagnostic accuracy for acute diverticulitis. 1
- In a clinical scoring system with 86% diagnostic accuracy, CRP ≥50 mg/L was identified as one of the independent predictors of acute left-sided colonic diverticulitis. 1
- Initial laboratory workup for suspected diverticulitis should include CRP measurement along with complete blood count and basic metabolic panel. 2
CRP Levels Correlate Directly with Disease Severity
The magnitude of CRP elevation predicts whether diverticulitis is uncomplicated versus complicated, with clear thresholds established:
Uncomplicated Diverticulitis
- Median CRP: 87 mg/L (range 48-151 mg/L) 1, 3
- CRP <140-150 mg/L indicates likely uncomplicated disease that can often be managed without antibiotics in immunocompetent patients. 4, 5
Complicated Diverticulitis
- Median CRP: 224 mg/L (range 99-284 mg/L) 1, 3
- CRP >150 mg/L is an independent risk factor for complicated diverticulitis (specificity 65%, sensitivity 85%). 1, 6
- CRP >170-175 mg/L is the optimal threshold for predicting severe disease requiring surgery or percutaneous drainage (87.5% sensitivity, 91.1% specificity). 1, 7, 3
- CRP >224 mg/L is strongly associated with complicated diverticulitis. 4
Progressive Risk Stratification
- CRP 25 mg/L: 15% chance of complicated diverticulitis 3
- CRP 100 mg/L: 23% chance of complicated diverticulitis 3
- CRP 250 mg/L or higher: 47% chance of complicated diverticulitis 3
CRP Predicts Clinical Outcomes and Mortality
Patients with CRP >150 mg/L have significantly increased risk of postoperative mortality. 1, 6
- Mean CRP in patients who died from diverticulitis: 207 mg/L 1, 6
- Mean CRP in patients who survived: 139 mg/L 1, 6
- CRP >150 mg/L combined with free abdominal fluid on CT are independent variables predicting postoperative mortality. 1, 6
Clinical Application Algorithm
For CRP <140-150 mg/L:
- Likely uncomplicated disease 4, 5
- If afebrile and clinically stable: observation without antibiotics is appropriate in immunocompetent patients 4, 5
- Close outpatient monitoring within 48-72 hours 4, 5
For CRP 150-175 mg/L:
- Threshold zone for complicated disease risk 4
- Strongly consider antibiotic therapy even if imaging shows "uncomplicated" disease 4, 5
- CT examination should always be performed 1, 6
For CRP >170-175 mg/L:
- High risk for severe diverticulitis requiring surgery or drainage 1, 4, 7
- Do not discharge without close follow-up 4, 5
- Greater probability of requiring surgical treatment or percutaneous intervention 1, 7
Important Caveats
CRP should not be used as a predictor of severity if concomitant conditions affect baseline levels. 1
- Corticosteroid therapy suppresses CRP production, making it unreliable for severity assessment in these patients. 8
- Aspirin does not significantly affect CRP's discriminative value (CRP >90 mg/L maintained 88% sensitivity and 75% specificity for complicated disease in aspirin users). 8
- In very acutely onset disease, CRP values might not have risen yet, as CRP peaks at 48 hours after inflammatory insult. 1, 9
White blood cell count and body temperature have no diagnostic value in discriminating complicated from uncomplicated diverticulitis—only CRP is useful. 3