Hypokalemia

Incredibly Easy!

IN HYPOKALEMIA, the serum potassium level drops below 3.5 mEq/liter. Because the normal range for serum potassium is narrow (3.5 to 5.0 mEq/liter at many labs), a slight decrease has profound consequence.

How does it happen? Remember that the body can't conserve potassium, so inadequate potassium intake and excessive potassium output can upset the balance and cause hypokalemia.

What causes it?

Not enough intake: Inadequate potassium intake causes a drop in the body's overall potassium level.

Too much output: Intestinal fluids contain large amounts of potassium. Severe gastrointestinal fluid losses from suction, lavage, diarrhea, or. prolonged vomiting can deplete the body's potassium supply. Potassium also can be depleted through the kidneys by osmotic diuresis from high urine glucose levels.

Drugs can cause problems: Diuretics (especially thiazide and furosemide), corticosteroids, insulin, cisplatin, and certain antibiotics (gentamicin, carbenicillin, and amphotericin B, for instance) also cause potassium loss.

Excessive insulin secretion, whether endogenous or exogenous, may shift potassium into the cells. Potassium levels also drop when adrenergic drugs such as epinephrine and albuterol are used to treat asthma.

Diseases can wreak havoc too: Disorders associated with hypokalemia are hepatic disease, hyperaldosteronism, acute alcoholism, heart failure, and malabsorption syndrome.

What to look for

Because potassium is vital to many body functions, hypokalemia causes multisystemic signs and symptoms. Assess for the following red flags.

* Neuromuscular alerts: Skeletal muscle weakness, especially in the legs, is a sign of a moderate potassium loss. As weakness progresses, the patient develops paresthesia and leg cramps. Deep tendon reflexes may be decreased or absent and respiratory muscles can become paralyzed. Because potassium affects cell function, hypokalemia can lead to rhabdomyolysis.

* Cardiovascular alerts: The patient's pulse may be weak and irregular, and he may have orthostatic hypotension. Electrocardiograms may show a flattened T wave, a depressed ST segment, and a characteristic U wave. Arrhythmias associated with hypotension are premature ventricular contractions and ventricular tachycardia and fibrillation. Watch for hypokalemia in a patient taking digoxin, especially if he's also taking a diuretic; hypokalemia can potentiate the action of the digoxin and cause a toxic reaction.

Now hypokalemia is treated

Focus on restoring a normal potassium balance, preventing serious complications, and removing or treating the underlying causes. Treatment, which varies depending on the severity of the imbalance, may include the following interventions.

* Place the patient on a high-- potassium diet.

* If increasing dietary potassium is insufficient to treat moderate hypokalemia, provide oral potassium supplements.

* A patient who has severe hypokalemia or who can't take oral supplements may need IN. potassium replacement therapy. For more on I.V. potassium administration, see "How to Safeguard Delivery of High-Alert IN. Drugs," by Lynn Hadaway in Nursing2001's February issue (pp 36-42).

* If the patient is on a diuretic, switch to a potassium-sparing one, such as spironolactone.

How you intervene

Careful monitoring and skilled interventions can help prevent hypokalemia and spare your patient from its associated complications.

Source: Fluid, & Electrolytes Made Incredibly Easy! 2nd edition, Springhouse Corp., 2002.

TEACHING YOUR PATIENTS ABOUT HYPOKALEMIA

When you explain hypokalemia, cover these topics with your patient, then evaluate his learning.

* signs, symptoms, and complications of hypokalemia

* causes and risk factors

* prevention of future episodes

* medication, including dosages and possible adverse effects

* need for a potassium-rich diet

* warning signs and symptoms to report to the primary care provider.

Copyright Springhouse Corporation Mar 2002
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