Hypokalemia

Excerpt

Hypokalemia Overview

Hypokalemia is one of the most common electrolyte disturbances seen in clinical practice. The condition is more prevalent than hyperkalemia, though most hypokalemia cases are mild. Although variation exists, an acceptable lower limit for normal serum potassium is 3.5 mmol/L. Hypokalemia is classified according to severity. A serum potassium level of 3 to 3.4 mmol/L is classified as mild. A serum potassium level of 2.5 to 3 mmol/L is classified as moderate. Serum potassium levels less than 2.5 mmol/L are classified as severe.

Symptoms of hypokalemia vary depending on the severity and underlying cause but may include muscle weakness, fatigue, cramping, palpitations, and constipation. Severe hypokalemia can lead to life-threatening complications, such as fatal arrhythmias or respiratory muscle paralysis.

Hypokalemia must be addressed promptly to prevent complications. Long-term management may involve monitoring potassium levels, adjusting medications, and addressing any underlying medical conditions contributing to hypokalemia.

Summary of Potassium Regulation

Potassium is a predominantly intracellular electrolyte, the most abundant cation in cell regulation and cellular processes. The fraction of potassium in the extracellular fluid is small. Thus, plasma or serum levels are unreliable indicators of total body potassium stores. The body's potassium level is tightly regulated by the kidneys, digestive tract, endocrine system, and cells actively participating in transcellular shifts, such as the skeletal muscles. Cellular potassium uptake is promoted by alkalemia, insulin, β-adrenergic stimulation, aldosterone, and xanthines, such as caffeine.

Potassium deficiency may arise from various causes, such as poor nutrition, endocrine disorders, diarrhea, medication intake, and prior surgeries. Hypokalemia may thus be a manifestation of a more serious disorder.