Which sign is most consistent with hypokalemia?

• A. Muscle weakness
• B. Tachycardia
• C. Hyperglycemia
• D. Weight gain

Answer: (A)

Potassium helps set the resting membrane potential and determine how easily cells can fire. When potassium is low, the resting membrane potential becomes more negative (hyperpolarizes), making it harder for muscle cells to reach the threshold for contraction. This reduced excitability leads to muscle weakness and fatigue, which are classic signs of hypokalemia.

Tachycardia can occur with electrolyte disturbances, but it’s not as characteristic as muscle weakness. Hyperglycemia and weight gain are not typical features of low potassium.