Potassium, Plasma

Potassium helps your heart beat regularly and your muscles work properly. Your kidneys control potassium levels, which can be affected by medications, diet, and health conditions.

When elevated: Hyperkalemia can cause muscle weakness, cardiac arrhythmias, and potentially fatal heart rhythm disturbances. Values above 5.5 mEq/L require urgent evaluation, and levels above 6.5 mEq/L constitute a medical emergency requiring immediate treatment. When low: Hypokalemia increases risk of cardiac arrhythmias, muscle weakness, cramping, and constipation. Chronic low potassium can impair kidney concentrating ability and glucose metabolism. Severe hypokalemia below 2.5 mEq/L can be life-threatening.

Potassium is critical for athletes because intense training depletes intracellular stores through sweat loss and muscle breakdown, potentially impairing muscle function, recovery, and cardiac rhythm stability. Adequate potassium supports aerobic capacity, reduces cramping risk, and ensures proper nervous system signaling during high-intensity efforts.