A patient with heart failure on Losartan and Spironolactone shows tall peaked T-waves on EKG. Which lab finding confirms this condition?

A patient with heart failure on Losartan and Spironolactone shows tall peaked T-waves on EKG. Which lab finding confirms this condition?

• A. Na+ 135
• B. BNP 560
• C. K+ 8.0
• D. K+ 1.5

Answer: (C)

Hyperkalemia is the key concept. Tall, peaked T waves on an ECG are a classic sign of elevated potassium. In heart failure, spironolactone (a potassium-sparing diuretic) and losartan (an ARB) can raise potassium levels by reducing its excretion, so a high K+ level must be suspected when those ECG changes appear. The lab finding that confirms this is a markedly elevated potassium, such as K+ = 8.0 mEq/L. Other values don’t match the electrolyte disturbance: Na 135 is near normal, BNP reflects heart failure status but not potassium, and a low potassium (K+ 1.5) would cause different ECG changes (not tall T waves). This level is dangerous and requires prompt evaluation and management to protect the heart.

Hyperkalemia is the key concept. Tall, peaked T waves on an ECG are a classic sign of elevated potassium. In heart failure, spironolactone (a potassium-sparing diuretic) and losartan (an ARB) can raise potassium levels by reducing its excretion, so a high K+ level must be suspected when those ECG changes appear. The lab finding that confirms this is a markedly elevated potassium, such as K+ = 8.0 mEq/L. Other values don’t match the electrolyte disturbance: Na 135 is near normal, BNP reflects heart failure status but not potassium, and a low potassium (K+ 1.5) would cause different ECG changes (not tall T waves). This level is dangerous and requires prompt evaluation and management to protect the heart.