What bloodwork is indicated for diverticulitis (inflammation of the diverticula)?

From the Guidelines

Blood tests for diverticulitis should include a complete blood count (CBC) to check for elevated white blood cells, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) to measure inflammation levels, as well as a comprehensive metabolic panel to assess kidney and liver function, with antibiotic treatment advised in patients with uncomplicated diverticulitis who have comorbidities, are frail, or have a CRP >140 mg/L or baseline white blood cell count > 15 × 10^9 cells per liter, as recommended by the American Gastroenterological Association 1. When evaluating patients with suspected diverticulitis, it is essential to consider the following key points:

• A normal white blood cell count ranges from 4,500 to 11,000 cells/μL, but in diverticulitis, this can rise above 12,000 cells/μL 1.
• CRP and ESR are commonly ordered to measure inflammation levels in the body, with a CRP >140 mg/L indicating a higher risk of complications 1.
• Additional tests may include a comprehensive metabolic panel to assess kidney and liver function, and blood cultures if systemic infection is suspected 1.
• The American College of Physicians suggests that clinicians use abdominal CT imaging when there is diagnostic uncertainty in a patient with suspected acute left-sided colonic diverticulitis, with CT imaging associated with very high sensitivity and specificity to make an accurate diagnosis of diverticulitis 1.
• Predictors of progression to complicated disease among patients with uncomplicated acute diverticulitis include symptoms lasting longer than 5 days, vomiting, systemic comorbidity, high C-reactive protein levels (>140 mg/L), and CT findings of pericolic extraluminal air, fluid collection, or a longer inflamed colon segment 1.
• Antibiotic treatment is advised in patients with complicated diverticulitis or uncomplicated diverticulitis with a fluid collection or longer segment of inflammation on CT scan, with the regimen usually including broad-spectrum agents with gram-negative and anaerobic coverage 1.

From the Research

Diverticulitis Bloodwork

• Initial laboratory studies for diverticulitis include a complete blood count, basic metabolic panel, urinalysis, and measurement of C-reactive protein (CRP) 2, 3.
• CRP has been identified as a useful biomarker of inflammation in diverticulitis, with higher levels indicating complicated disease 4, 5.
• The sensitivity and specificity of CRP in distinguishing between complicated and uncomplicated diverticulitis have been reported to be 88% and 75%, respectively, with a cutoff value of 90 mg/ml 4.
• However, the usefulness of CRP as a biomarker may be limited in patients taking corticosteroids, as these medications can down-regulate CRP production 4.
• Elevated CRP levels, particularly above 150 mg/l, may indicate the need for further imaging, such as CT scanning, to assess for complications of diverticulitis 5.

Laboratory Tests

• Complete blood count (CBC) to evaluate for signs of infection or inflammation 2, 3.
• Basic metabolic panel (BMP) to assess for any electrolyte imbalances or kidney function abnormalities 2, 3.
• Urinalysis to evaluate for any urinary tract infections or other abnormalities 2, 3.
• C-reactive protein (CRP) measurement to assess for inflammation and potential complications of diverticulitis 2, 3, 4, 5.