Which lab result confirms heart failure?

• A. K+ 5.6
• B. BNP 820
• C. BUN 9
• D. Troponin <0.02

Answer: (B)

The main idea is that BNP rises when the heart muscle is stretched from volume overload, which happens in heart failure. A BNP level of 820 is markedly elevated, which strongly supports a diagnosis of heart failure and correlates with the presence of ventricular strain and fluid overload.

The other labs don’t confirm heart failure on their own. A potassium of 5.6 can occur for reasons unrelated to HF and doesn’t diagnose it. A BUN of 9 is normal-ish and renal function alone doesn’t establish HF. A troponin level below 0.02 suggests no acute myocardial injury, which helps rule out a heart attack but doesn’t confirm heart failure by itself. So the elevated BNP is the best lab finding to confirm heart failure.