Symptoms and Treatment of Hypokalemia
Hypokalemia (serum potassium <3.5 mEq/L) can cause life-threatening cardiac arrhythmias, neuromuscular dysfunction, and other serious complications that require prompt recognition and treatment based on severity. 1
Symptoms of Hypokalemia
Cardiac Manifestations
- ECG changes including T-wave flattening, ST-segment depression, and prominent U waves 1
- Cardiac arrhythmias, particularly ventricular arrhythmias 1
- First or second-degree atrioventricular block or atrial fibrillation 1
- Risk of progression to ventricular fibrillation, pulseless electrical activity (PEA), or asystole if left untreated 1
- Increased risk of digitalis toxicity in patients taking digoxin 1
Neuromuscular Symptoms
- Muscle weakness, which is often the most common symptom of symptomatic severe hypokalemia 2
- Flaccid paralysis in severe cases 1
- Paresthesia (abnormal sensations) 1
- Depressed deep tendon reflexes 1
- Respiratory difficulties due to respiratory muscle weakness 1
Other Symptoms
- Vague symptoms when potassium is between 3.0-3.5 mEq/L 3
- Significant clinical problems typically occur when serum potassium falls below 2.7 mEq/L 3
- Ileus (decreased intestinal motility) 4
Classification of Hypokalemia
Common Causes of Hypokalemia
- Decreased intake (malnutrition) 5, 2
- Renal losses (diuretics, renal tubular disorders) 5, 2
- Gastrointestinal losses (vomiting, diarrhea) 5, 6
- Transcellular shifts (insulin administration, alkalosis) 5
- Medication-related (diuretics, certain herbal medicines) 2
Treatment of Hypokalemia
Assessment of Severity
- Urgent treatment required for:
Oral Replacement (Preferred Method)
- Use when:
- Potassium chloride is the preferred oral supplement for most cases 7
- Potassium bicarbonate, citrate, acetate, or gluconate should be used in patients with metabolic acidosis 7
Intravenous Replacement
- Reserved for severe hypokalemia (≤2.5 mEq/L), ECG changes, neurologic symptoms, cardiac ischemia, or patients on digitalis 4
- Slow infusion of potassium is recommended; bolus administration is ill-advised and potentially dangerous (Class III, LOE C) 1
- Frequent monitoring of serum potassium levels is essential during IV replacement 4
Special Considerations
- In diabetic ketoacidosis, potassium replacement should begin with fluid therapy if potassium is low, and insulin treatment should be delayed until potassium concentration is restored to ≥3.3 mEq/L to avoid arrhythmias or cardiac arrest 1
- Consider adding potassium-sparing diuretics in cases of persistent hypokalemia due to renal potassium wasting 4
- Magnesium deficiency often coexists with hypokalemia and may need concurrent treatment 1
Prevention in High-Risk Patients
- Serum potassium should be maintained at ≥4.0 mEq/L in patients with heart failure 1
- Potassium supplementation is indicated for prevention of hypokalemia in digitalized patients or those with significant cardiac arrhythmias 7
- Regular monitoring of serum potassium in patients on diuretics, RAAS inhibitors, or NSAIDs 7
Common Pitfalls
- Serum potassium is an inaccurate marker of total-body potassium deficit; mild hypokalemia may be associated with significant total-body potassium deficits 4
- Overcorrection can lead to hyperkalemia, which carries its own risks 4
- Failure to address the underlying cause will result in recurrent hypokalemia 5
- Solid oral dosage forms of potassium chloride can produce ulcerative and/or stenotic lesions of the gastrointestinal tract 7
Remember that the goals of therapy should be to correct the potassium deficit without provoking hyperkalemia, with treatment speed and extent dictated by clinical severity and guided by frequent reassessment of serum potassium concentration 4.