What laboratory tests should be ordered for a patient suspected of having pericarditis?

Laboratory Tests for Suspected Pericarditis

Order inflammatory markers (CRP and/or ESR), complete blood count with differential, cardiac biomarkers (troponin and creatine kinase), renal function tests, and liver function tests as the initial laboratory panel for all patients with suspected pericarditis. 1

Core Laboratory Panel (Class I Recommendation)

The European Society of Cardiology provides a Class I recommendation for routine blood tests in all cases of suspected pericardial disease, which should include: 1

Inflammatory Markers

• C-reactive protein (CRP) - essential for diagnosis and should be used to guide treatment duration and assess therapeutic response 1, 2, 3
• Erythrocyte sedimentation rate (ESR) - alternative or complementary marker of inflammation 1, 3
• White blood cell count with differential - assesses for infection or inflammatory response 1, 3

Cardiac Biomarkers

• Troponin - detects myocardial involvement (myopericarditis) 1, 2, 3
• Creatine kinase (CK) - additional marker of myocardial damage 1, 3

Important caveat: Elevated cardiac biomarkers indicate concomitant myocarditis rather than primary pericardial disease and do not exclude the diagnosis of pericarditis. 2, 3

Organ Function Tests

• Renal function tests - evaluate kidney function and systemic involvement 1, 3
• Liver function tests - assess for systemic involvement 1, 3

Additional Testing Based on Clinical Context

For High-Risk Patients

High-risk features include fever >38°C, subacute course, large pericardial effusion, cardiac tamponade, failure to respond to NSAIDs, myopericarditis, immunosuppression, trauma, or anticoagulant therapy. 1, 2

Further testing should be directed by clinical presentation: 1, 3

Suspected Autoimmune Pericarditis

• ANA, ENA, ANCA - screen for autoimmune conditions 3
• Ferritin - if Still's disease is suspected 3

Suspected Tuberculous Pericarditis

• IGRA testing (Quantiferon, ELISpot) - particularly important in endemic areas 3

Suspected Viral Pericarditis

• PCR for viral genomes from pericardial fluid if obtained 3
• Serology for HCV and HIV 3

Suspected Bacterial Pericarditis

• Blood cultures - must be obtained before antibiotic administration 3, 4, 5
• Pericardial fluid analysis (if pericardiocentesis performed) should include cytology, PCR, and microbiology cultures 2

Critical Pitfalls to Avoid

Normal inflammatory markers do not exclude pericarditis, especially if the patient is already receiving anti-inflammatory treatment. 2, 3 The diagnosis of pericarditis requires at least 2 of 4 clinical criteria (chest pain, pericardial rub, ECG changes, or effusion), and laboratory tests serve as supportive evidence rather than diagnostic criteria. 2, 6, 7

ECG changes may be absent in up to 40% of cases, so laboratory markers become particularly important when classic ECG findings are not present. 2

In suspected purulent pericarditis (particularly with pneumonia and new pericardial effusion), this represents a medical emergency requiring immediate intervention, as it is virtually fatal without antibiotics. 4, 5