Potassium Imbalance

What is Potassium Imbalance ?

Potassium - a cation and the dominant cellular electrolyte-facilitates contraction of both skeletal and smooth muscles, including myocardial contraction. It figures prominently in nerve impulse conduction, acid-base balance, enzyme action, and cell membrane function. Because serum potassium level has such a narrow range (3.5 to 5 mEq/L), a slight deviation in either direction can produce profound consequences.

Causes of Potassium Imbalance

Hypokalemia rarely results from a dietary deficiency because many foods contain potassium. Instead, potassium loss results from:

• excessive GI losses, such as vomiting, gastric suction, diarrhea, villous adenoma, and laxative abuse
• chronic renal disease, with tubular potassium wasting
• certain drugs, especially potassium-wasting diuretics, steroids, and certain sodium-containing antibiotics (carbenicillin)
• alkalosis or insulin effect, which causes potassium shifting into cells without depletion of total body potassium
• prolonged potassium-free l.V. therapy
• hyperglycemia, causing osmotic diuresis and glycosuria
• Cushing's syndrome, primary hyperaldosteronism, excessive ingestion of licorice, and severe serum magnesium deficiency.

Hyperkalemia usually results from reduced excretion by the kidneys. This may be due to acute or severe chronic renal failure, oliguria due to shock or severe dehydration, or the use of potassium-sparing diuretics such as triamterene by patients with renal disease. Inadequate potassium excretion may also be due to hyperaldosteronism or Addison's disease.

Signs & Symptoms of Potassium Imbalance

Signs of potassium deficiency include:

• slow thought processes
• abnormally dry skin
• depression
• reduced bowel sounds
• anorexia
• abdominal distension
• edema
• nervousness
• irregular heartbeat
• high cholesterol levels
• muscular fatigue
• growth impairment
• headaches
• proteinuria and glucose intolerance

Electrocardiograph changes accompanying hypokalemia are ST depression, flat T waves, U waves and dysrhythmias. The pulse will be fast, then slow. If digitalized, monitor for digitalis toxicity.

Diagnostic Tests

Serum potassium levels allow definitive diagnosis of a porassium abnormality. In hypokalemia, potassium levels are less than 3.5 mEq/L. In hyperkalemia, levels are more than 5 mEq/L.

Additional tests may be necessary to determine the underlying cause of the imbalance.

Treatment

Hypokalemia treatment should involve increased dietary intake of potassium or oral supplements with potassium salts. Potassium chloride is the preferred choice. Edematous patients with diuretic-induced hypokalemia should receive a potassium-sparing diuretic such as spironolactone.

Patients with GI potassium loss or severe potassium depletion require I.V. potassium replacement therapy. If hypocalcemia is also present, treatment should include calcium replacement.

For patients with hyperkalemia, treatment consists of withholding potassium and administering a carion exchange resin orally or by enema. Sodium polystyrene sulfonate (Kayexalate) with 70% sorbitol exchanges sodium ions for potassium ions in the intestine.

In an emergency, rapid infusion of 10% calcium gluconate decreases myocardial irritability and temporarily prevents cardiac arrest but doesn't correct serum potassium excess; it's also contraindicated in patients receiving digoxin.

Prevention Tips

• If you take digitalis and diuretics, have frequent blood studies to monitor potassium levels.
• Learn as much as you can about your condition, your drugs and how you can prevent a potassium imbalance.