What laboratory tests are used for the diagnosis and management of heart failure?

Laboratory Tests for Heart Failure Diagnosis and Management

The initial laboratory evaluation of patients presenting with heart failure should include complete blood count, urinalysis, serum electrolytes (including calcium and magnesium), blood urea nitrogen, serum creatinine, fasting blood glucose (glycohemoglobin), lipid profile, liver function tests, iron studies, and thyroid-stimulating hormone. 1

Core Laboratory Tests for Initial Diagnosis

• Complete blood count - to identify anemia which can exacerbate or mimic heart failure symptoms 1
• Urinalysis - to detect proteinuria or other renal abnormalities that may contribute to fluid retention 1
• Serum electrolytes (including calcium and magnesium) - to identify electrolyte imbalances that may affect cardiac function or be caused by diuretic therapy 1
• Blood urea nitrogen and serum creatinine - to assess renal function, which is crucial for management decisions and prognosis 1
• Fasting blood glucose (glycohemoglobin) - to identify diabetes, which is both a risk factor and comorbidity in heart failure 1
• Lipid profile - to assess cardiovascular risk factors 1
• Liver function tests - to evaluate hepatic congestion and assess for underlying liver disease 1
• Thyroid-stimulating hormone - to rule out thyroid disorders that can cause or exacerbate heart failure 1
• Iron studies (serum iron, ferritin, transferrin saturation) - to identify iron deficiency, which is common in heart failure and impacts symptoms and outcomes 1

Biomarkers for Diagnosis and Risk Stratification

• B-type natriuretic peptide (BNP) or N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements are essential for:

  • Supporting or excluding the diagnosis of heart failure in patients with dyspnea, especially when clinical uncertainty exists 1
  • Risk stratification in patients with chronic heart failure 1
  • Establishing prognosis in patients hospitalized for heart failure 1
  • Monitoring disease progression and response to therapy 1

• BNP or NT-proBNP levels should be measured:

  • At initial presentation with suspected heart failure 1
  • At hospital admission for acute heart failure 1
  • Prior to discharge to establish post-discharge prognosis 1

• Cardiac troponin levels may be useful for:

  • Determining prognosis or disease severity in hospitalized patients with acute decompensated heart failure 1
  • Identifying potential ischemic etiology 1

Additional Testing Based on Clinical Suspicion

• Screening for hemochromatosis - when iron overload is suspected 1
• HIV testing - in patients with risk factors or unexplained cardiomyopathy 1
• Diagnostic tests for rheumatologic diseases - when clinical suspicion exists 1
• Testing for amyloidosis - in patients with unexplained heart failure with preserved ejection fraction, particularly older patients 1
• Pheochromocytoma screening (metanephrine measurements) - in patients with labile hypertension and heart failure 1, 2

Serial Laboratory Monitoring

• Renal function and electrolytes should be monitored regularly, especially:
  • After initiation or dose adjustment of diuretics, ACE inhibitors, ARBs, or aldosterone antagonists 1
  • During episodes of acute illness 1
  • In patients with severe heart failure requiring frequent medication adjustments 1

Non-Laboratory Diagnostic Tests

While not laboratory tests, these are essential components of heart failure diagnosis:

• 12-lead electrocardiogram - required for all patients with suspected heart failure 1
• Chest radiography (PA and lateral) - to assess heart size and pulmonary congestion 1
• Two-dimensional echocardiography with Doppler - to assess left ventricular ejection fraction, size, wall thickness, and valve function 1

Emerging Laboratory Tests

• Metabolomic profiling - panels of metabolites including histidine, phenylalanine, spermidine, and phosphatidylcholine C34:4 may provide diagnostic value similar to BNP 3
• Biomarkers of myocardial injury or fibrosis - may be considered for additional risk stratification in outpatients with chronic heart failure 1

Pitfalls and Caveats

• BNP and NT-proBNP levels can be elevated in conditions other than heart failure, including:

  • Advanced age
  • Renal dysfunction
  • Atrial fibrillation
  • Pulmonary hypertension
  • Acute pulmonary embolism 1

• BNP and NT-proBNP levels may be falsely low in:

  • Obesity
  • Flash pulmonary edema
  • HFpEF (relative to HFrEF at similar clinical severity) 1

• Laboratory abnormalities that may complicate heart failure management include:

  • Hyponatremia - associated with poor prognosis and may limit diuretic efficacy
  • Worsening renal function - may require adjustment of heart failure medications
  • Hyperkalemia - may occur with RAAS inhibitors and require dose adjustment 1