What lab values should be evaluated when assessing a patient with chronic congestive heart failure (CHF)?

Laboratory Assessment for Chronic Heart Failure

When assessing a patient with chronic CHF, you should routinely check: hemoglobin/WBC, sodium, potassium, urea, creatinine with eGFR, liver function tests (bilirubin, AST, ALT, GGTP), glucose, HbA1c, TSH, iron studies (ferritin, TSAT/TIBC), and natriuretic peptides. 1

Core Laboratory Panel (Class I Recommendation)

The European Society of Cardiology provides the most comprehensive and recent guideline framework for laboratory assessment in chronic heart failure:

Hematologic Tests

• Complete blood count including hemoglobin and white blood cell count to identify anemia, which can exacerbate heart failure symptoms and worsen outcomes 1, 2

Renal and Electrolyte Assessment

• Sodium, potassium, urea, and creatinine with estimated GFR are essential for evaluating renal function, which directly impacts medication dosing, prognosis, and fluid management 1, 2
• These values require serial monitoring, especially after initiating or adjusting doses of diuretics, ACE inhibitors, ARBs, or aldosterone antagonists 2

Metabolic Assessment

• Glucose and HbA1c to identify diabetes, which is both a common comorbidity and risk factor for worse outcomes in heart failure 1, 2
• Lipid profile for cardiovascular risk stratification 2, 3

Hepatic Function

• Liver function tests including bilirubin, AST, ALT, and GGTP to evaluate hepatic congestion from right heart failure and assess for underlying liver disease 1, 2
• Even "normal range" LFT values have prognostic significance—lower albumin and alanine transaminase, along with higher aspartate transaminase and alkaline phosphatase, are independently associated with decreased survival 4

Endocrine Assessment

• Thyroid-stimulating hormone (TSH) to rule out thyroid disorders that can mimic or exacerbate heart failure 1, 2

Iron Status

• Ferritin and transferrin saturation (TSAT/TIBC) to identify iron deficiency, which is common in heart failure and impacts symptoms and outcomes even without anemia 1, 2

Biomarkers (Class IIa Recommendation)

Natriuretic Peptides

• BNP or NT-proBNP should be considered for risk stratification, establishing prognosis, and monitoring disease progression and response to therapy 1, 2
• For chronic/non-acute presentations, the optimum exclusion cut-off is 125 pg/mL for NT-proBNP and 35 pg/mL for BNP 1

Important caveats: BNP/NT-proBNP can be falsely elevated in advanced age, renal dysfunction, atrial fibrillation, and pulmonary hypertension, and falsely low in obesity and HFpEF 2

Cardiac Troponin

• Troponin levels may be useful for determining prognosis or disease severity and identifying potential ischemic etiology 2, 5

Additional Testing Based on Clinical Suspicion (Class IIa)

When specific etiologies are suspected, consider:

• Hemochromatosis screening when iron overload is suspected 2, 3
• HIV testing in patients with risk factors or unexplained cardiomyopathy 2, 3
• Rheumatologic disease testing when clinical suspicion exists 2, 3
• Amyloidosis testing in unexplained HFpEF, particularly in older patients 2, 3

Serial Monitoring Strategy

Renal function and electrolytes require regular monitoring in the following situations 2:

• After initiation or dose adjustment of diuretics, ACE inhibitors, ARBs, or aldosterone antagonists
• During episodes of acute illness (especially with sodium/water loss from diarrhea or vomiting)
• In patients with severe heart failure requiring frequent medication adjustments
• When NSAIDs or other drugs affecting renal function are started or adjusted 1

Common Pitfalls to Avoid

• Don't dismiss "normal range" LFT values—they still provide independent prognostic information, with mortality increasing at lower albumin/ALT and higher AST/alkaline phosphatase levels even within normal ranges 4
• Don't rely solely on natriuretic peptides—they have limitations in obesity, flash pulmonary edema, and HFpEF 2
• Don't forget urinalysis—it detects proteinuria and renal abnormalities contributing to fluid retention 2, 3
• Monitor for hyponatremia, worsening renal function, and hyperkalemia—these laboratory abnormalities commonly complicate heart failure management 2