What tests should be ordered for a patient with an elevated C-Reactive Protein (CRP) level?

Workup for CRP 7.0 mg/L

For a CRP of 7.0 mg/L, repeat the CRP measurement and perform a focused clinical assessment for infection or inflammatory conditions, followed by targeted testing based on symptoms and risk factors. 1

Initial Assessment

Repeat CRP testing is recommended for any CRP ≥10 mg/L, but given that 7.0 mg/L falls in an intermediate range (above cardiovascular risk thresholds but below traditional infection cutoffs), confirmation is prudent before extensive workup. 1

Clinical Evaluation

• Screen for infection/injury symptoms including fever, localizing pain, respiratory symptoms, or recent trauma 1, 2
• Measure body temperature to identify acute infectious processes 1
• Assess cardiovascular risk factors (chest pain, dyspnea, hypertension, diabetes, smoking) as CRP >3.0 mg/L indicates high cardiovascular risk 1
• Evaluate for inflammatory conditions including inflammatory bowel disease symptoms (diarrhea, abdominal pain, rectal bleeding) 3

Context-Specific Testing

If Infection Suspected

• Blood cultures if fever or acute symptoms are present 2
• Complete blood count to assess for leukocytosis or left shift 2
• Urinalysis and urine culture if urinary symptoms present
• Chest X-ray if respiratory symptoms present

If Cardiovascular Risk Assessment

• ECG and troponin if chest pain, dyspnea, or cardiac risk factors present 2
• Lipid panel and hemoglobin A1c for comprehensive cardiovascular risk stratification 1

If Inflammatory Bowel Disease Suspected

• Fecal calprotectin is more sensitive and specific than CRP for detecting intestinal inflammation and should be measured before arranging endoscopy 3
• CRP correlates less tightly with ulcerative colitis activity than fecal calprotectin, and patients may have normal CRP even during flares 3
• In Crohn's disease, elevated CRP suggests moderate to severe endoscopic activity but has limited negative predictive value 3

If Systemic Lupus Erythematosus Suspected

• Anti-dsDNA antibodies, complement levels (C3, C4), complete blood count, urinalysis 3
• Note: In SLE, significantly elevated CRP (especially >50 mg/L) suggests superimposed infection rather than lupus activity alone 3

If No Localizing Symptoms

• Liver function tests (AST, ALT) to evaluate for fatty liver disease, particularly in obese patients 2, 4
• Consider metabolic factors: Obesity alone can elevate CRP to this range through low-grade systemic inflammation 4

Common Pitfalls

• Do not assume infection based solely on CRP 7.0 mg/L: This level can reflect cardiovascular risk, obesity, smoking, or mild inflammation rather than acute bacterial infection 1, 4
• Avoid relying on CRP alone for inflammatory bowel disease: Normal CRP does not exclude active disease, particularly in ulcerative colitis 3
• Do not use CRP to monitor cardiovascular treatment response: Significant variation occurs independent of treatment 1

Follow-Up Strategy

• If CRP remains elevated on repeat testing (3-6 months) without identified cause, consider imaging (CT/MRI) for occult infection, malignancy, or inflammatory process 1, 2
• If specific inflammatory condition identified, repeat CRP after treatment to confirm normalization, as CRP decreases rapidly with resolution of inflammation 1, 5
• If cardiovascular risk is the primary concern, consider statin therapy and lifestyle modifications including weight loss 1