What laboratory tests, besides Brain Natriuretic Peptide (BNP), are indicative of heart failure in patients suspected of having the condition?

Laboratory Tests Beyond BNP for Heart Failure Diagnosis

In addition to BNP, the essential laboratory tests for heart failure include routine biochemical markers (sodium, potassium, creatinine/eGFR), complete blood count (hemoglobin, hematocrit, ferritin), thyroid-stimulating hormone, blood glucose, and liver enzymes—all of which provide diagnostic clues and prognostic information while guiding treatment decisions. 1

Core Routine Laboratory Panel

The European Society of Cardiology guidelines establish a comprehensive baseline laboratory evaluation for all patients with suspected heart failure 1:

Biochemical Tests

• Electrolytes: Sodium and potassium levels are critical for monitoring diuretic therapy and detecting complications from renin-angiotensin system blockers 1
• Renal function: Creatinine and estimated glomerular filtration rate (eGFR) are essential both for initial assessment and ongoing monitoring, especially during medication titration 1
• Blood glucose: Undiagnosed diabetes is common in heart failure patients and requires identification 1
• Liver enzymes: These may be abnormal in heart failure itself and are important when considering medications like amiodarone or warfarin 1

Hematological Tests

• Complete blood count: Hemoglobin, hematocrit, ferritin, leucocytes, and platelets provide diagnostic and prognostic information 1
• Anemia assessment: Anemia is a common comorbidity that can mimic or exacerbate heart failure symptoms and affects natriuretic peptide interpretation 2

Endocrine and Metabolic Tests

• Thyroid-stimulating hormone (TSH): Thyroid disease can mimic or aggravate heart failure and must be excluded 1
• Fasting lipid profile: Recommended in the initial evaluation to assess cardiovascular risk 1

Additional Diagnostic Tests in Select Patients

The ACC/AHA guidelines recommend targeted testing based on clinical suspicion 1:

• Hemochromatosis screening: Consider when clinical features suggest iron overload 1
• HIV testing: Reasonable in patients with appropriate risk factors 1
• Rheumatologic disease markers: Test when clinical presentation suggests autoimmune etiology 1
• Amyloidosis workup: Pursue when low QRS voltage, increased wall thickness, or other suggestive features are present 1
• Pheochromocytoma testing: Consider with refractory hypertension or paroxysmal symptoms 1

Cardiac-Specific Biomarkers Beyond BNP

Troponins

• Cardiac troponin I or T: Useful for determining prognosis and disease severity in both acute decompensated heart failure and chronic heart failure 1
• Elevated troponin levels indicate myocardial injury and are associated with worse outcomes 1
• Particularly valuable when evaluating for acute coronary syndrome as a precipitant of decompensation 1

Other Biomarkers

• Markers of myocardial injury or fibrosis: May be considered for additional risk stratification in outpatients with chronic heart failure 1
• These complement natriuretic peptide testing but are not routinely required 1

Prognostic Value of Routine Labs

The ESC guidelines emphasize that routine laboratory tests provide valuable prognostic information beyond their diagnostic utility 1. Abnormalities in renal function, electrolytes, and hemoglobin correlate with disease severity and predict outcomes 1, 2.

Monitoring Strategy

Biochemical monitoring is particularly important 1:

• After initiating renin-angiotensin system blockers
• During dose up-titration of heart failure medications
• During intercurrent illnesses causing sodium and water loss (diarrhea, vomiting)
• When starting or adjusting medications affecting renal function or fluid homeostasis (NSAIDs, diuretics) 1

Critical Pitfalls to Avoid

• Don't skip TSH testing: Thyroid dysfunction is easily treatable and can completely explain or significantly contribute to heart failure symptoms 1
• Don't ignore renal function: Kidney dysfunction affects natriuretic peptide interpretation, medication dosing, and prognosis 1, 2
• Don't overlook anemia: This common comorbidity worsens heart failure symptoms and affects BNP interpretation 2
• Don't forget glucose screening: Diabetes is frequently undiagnosed in heart failure patients and requires identification for optimal management 1

Integration with Clinical Assessment

These laboratory tests must be interpreted alongside the complete clinical picture, including history, physical examination, ECG, chest X-ray, and echocardiography 1. No single test definitively diagnoses heart failure—the diagnosis requires integration of multiple data points 1. The laboratory panel serves to confirm the diagnosis, identify precipitating factors, detect comorbidities, guide therapy, and establish prognosis 1.