Medicine & USMLE

Hypokalemia

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  9. Hypokalemia

Summary

Hypokalemia is the medical term for low potassium, specifically potassium levels below 3.5 in the blood.  Causes of hypokalemia include medications like loop diuretics, thiazide diuretics, and insulin. Hypokalemia can also be caused by GI fluid loss, Cushing syndrome, and metabolic alkalosis.

Symptoms of hypokalemia include arrhythmias, specifically manifesting on EKG as flattened T waves and prominent U waves. Other symptoms include decreased or shallow respirations, muscle cramps, muscle weakness, and constipation.

Treatment of hypokalemia is performed by replenishing potassium through an IV or oral form.  IV potassium should NEVER be given through an IV push. Instead, the potassium must be diluted in saline and given through a pump at a maximum rate of 10 milliequivalents per hour. On the other hand, oral potassium may cause the side effect of esophagitis. This can be prevented by advising the patient to remain upright for 30 minutes after ingestion and to take the potassium with plenty of food and water.

Key Points

  • Hypokalemia
    • Low blood potassium <3.5 mEq/L
      • Hypo=low
      • Kal=potassium
      • Emia=in the blood
    • Causes
      • Medications
        • Potassium-wasting diuretics
          • Loop diuretics
          • Thiazide diuretics
        • Insulin
          • Pushes potassium out of the bloodstream and into the cell
        • Albuterol
        • Amphotericin B
        • Corticosteroids
        • Licorice root
      • GI Fluid Loss
        • Diarrhea
        • Vomiting
        • Prolonged NG suction
        • Wound drainage
      • Cushing’s Syndrome
        • Increased cortisol
      • Alkalosis
      • Water intoxication
    • Symptoms
      • Cardiovascular
        • Arrhythmias
        • Weak pulse
        • Hypotension
        • EKG changes
          • Flat T wave
          • Prominent U wave
          • ST depression
          • Prolonged PR interval
      • Respiratory
        • Shallow respirations
          • Diminished breath sounds
        • Respiratory failure
      • Neuromuscular
        • Muscle cramps
          • Often the first sign of hypokalemia
        • Weakness
        • Hyporeflexia
        • Confusion
      • GI
        • Constipation
          • Decreased bowel sounds
          • Paralytic ileus
          • Can lead to small bowel obstruction (SBO)
          • Abdominal distention
    • Nursing Interventions
      • IV Potassium (KCl)
        • Never given via IV push, IM or SC
          • Rapid infusion can spike blood potassium levels and cause cardiac arrest
        • Always diluted and given through an infusion pump.
          • Maximum recommended rate is 10 mEq/hr
          • KCl can cause irritation and discomfort at the IV site; if irritation occurs, slow the infusion
      • Oral potassium
        • May cause stomach upset. GI discomfort can be minimized by taking potassium with food and a full glass of water
        • May cause esophagitis, so patient should remain upright for at least 30 minutes following ingestion, as well as take with plenty of water
      • Increase potassium-rich foods in diet
      • Replace potassium-losing diuretics (e.g. thiazide diuretics) for potassium-sparing diuretics (e.g. spironolactone)