Potassium Imbalance
A cation that’s the dominant cellular electrolyte, potassium 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 the 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
Hypokalemia rarely results from a dietary deficiency because many foods contain potassium. Instead, potassium loss results from:
excessive GI losses, such as from vomiting, gastric suction, diarrhea, villous adenoma, or 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 effects, which cause potassium shifting into cells without true depletion of total body potassium
prolonged potassium-free I.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 hypoaldosteronism or Addison’s disease.
Hyperkalemia may also result from failure to excrete excessive amounts of potassium infused I.V. or administered orally. Another cause is massive release of intracellular potassium, such as can occur with burns, crushing injuries, severe infection, or acidosis.
Complications
Potassium imbalances may result in muscle weakness and flaccid paralysis and may also lead to cardiac arrest.
Assessment
The patient’s history and physical examination may reveal cardiovascular irregularities manifested by dizziness, postural hypotension, and arrhythmias.
The patient with hypokalemia may have GI complaints that include nausea and vomiting, anorexia, abdominal distention, constipation, paralytic ileus, and decreased peristalsis; the patient with hyperkalemia may have complaints that include nausea, diarrhea, and abdominal cramps.
The patient may also experience neuromuscular symptoms, such as weakness and hyporeflexia (with hypokalemia); skeletal muscle weakness, numbness, and tingling (with hyperkalemia); and flaccid paralysis or respiratory paralysis (with both imbalances).
Diagnostic tests
Serum potassium levels definitively diagnose a potassium 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 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.
Nursing priorityGuidelines for I.V. potassium administration
I.V. replacement of potassium is necessary only if hypokalemia is severe or if the patient can’t take supplements by mouth. Carefully monitor I.V. potassium replacement to prevent or lessen toxic effects. Follow these guidelines.
Never administer potassium by I.V. push or bolus; doing so may cause cardiac arrest.
I.V. infusion concentrations shouldn’t exceed 60 mEq/L. The infusion rate shouldn’t exceed 20 mEq/hour unless indicated. More concentrated potassium solutions may be used in patients with severe fluid restrictions.
Use volumetric devices whenever concentrations of more than 40 mEq/L are infused.
Monitor cardiac rhythm during rapid I.V. administration of potassium to avoid cardiac toxicity from inadvertent hyperkalemia. Report any irregularities immediately.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
