Feline Hypokalemia Study Guide

Overview and Clinical Importance

Hypokalemia is defined as a serum potassium concentration less than 3.5 mEq/L (mmol/L). It is one of the most common electrolyte abnormalities encountered in feline practice and represents a significant category on the NAVLE. Potassium is the body's major intracellular cation, with approximately 95-98% located within the intracellular fluid compartment. Potassium is responsible for maintaining the resting cell membrane potential, making it essential for normal neuromuscular function.

Cats are particularly susceptible to hypokalemia due to their unique anatomy (absence of a complete nuchal ligament) and their predisposition to chronic kidney disease. The hallmark clinical sign of feline hypokalemia is cervical ventroflexion - the inability to raise the head into a normal position, creating a characteristic "drooped head" appearance.

Potassium Physiology

Normal Potassium Homeostasis

The normal serum potassium concentration in cats is 3.5 to 5.5 mEq/L. Potassium homeostasis is maintained through a balance between dietary intake and excretion, primarily via the kidneys. The Na+/K+-ATPase pump maintains the steep concentration gradient between intracellular (approximately 140 mEq/L) and extracellular (approximately 4 mEq/L) compartments.