Depressed ST segments, flat T waves, and U waves present on ECG indicate which electrolyte abnormality?

Depressed ST segments, flat T waves, and U waves present on ECG indicate which electrolyte abnormality?

• A. Hypokalemia
• B. Hyperkalemia
• C. Hyponatremia
• D. Hypercalcemia

Answer: (A)

Low potassium slows cardiac repolarization and alters membrane excitability, leading to the ECG pattern described. Depressed ST segments reflect reduced ST activity, T waves become flattened, and a prominent U wave appears with hypokalemia. This combination—ST depression, flattened or inverted T waves, and U waves—is classic for low potassium. In contrast, hyperkalemia tends to produce tall, peaked T waves and widened QRS; hyponatremia doesn’t have a specific electrolyte-driven ECG pattern, and hypercalcemia shortens the QT interval. So the described findings point to hypokalemia.

Low potassium slows cardiac repolarization and alters membrane excitability, leading to the ECG pattern described. Depressed ST segments reflect reduced ST activity, T waves become flattened, and a prominent U wave appears with hypokalemia. This combination—ST depression, flattened or inverted T waves, and U waves—is classic for low potassium. In contrast, hyperkalemia tends to produce tall, peaked T waves and widened QRS; hyponatremia doesn’t have a specific electrolyte-driven ECG pattern, and hypercalcemia shortens the QT interval. So the described findings point to hypokalemia.