What are the causes and treatment (ttt) of hypokalemia (low potassium levels)?

Causes and Treatment of Hypokalemia

Hypokalemia (serum potassium <3.5 mEq/L) is commonly caused by gastrointestinal or renal losses and requires prompt treatment with oral or intravenous potassium supplementation based on severity, with careful attention to underlying causes. 1, 2

Causes of Hypokalemia

Decreased Intake

• Inadequate dietary intake (rarely causes hypokalemia alone) 3

Increased Losses

Gastrointestinal Losses

• Vomiting
• Diarrhea
• Nasogastric suction
• Fistulas
• Laxative abuse 4

Renal Losses

• Diuretic therapy (most common cause) 4
  • Loop diuretics (furosemide)
  • Thiazide diuretics
• Hyperaldosteronism
• Renal tubular disorders
• Magnesium deficiency
• High-dose antibiotics
• Polyuria 1, 4

Transcellular Shifts

• Insulin administration
• Beta-adrenergic stimulation
• Alkalosis
• Hypokalemic periodic paralysis 2, 5

Diagnosis

Clinical Presentation

• Mild: Often asymptomatic
• Moderate to severe:
  • Muscle weakness
  • Fatigue
  • Constipation
  • Cardiac arrhythmias
  • ECG changes (U waves, T-wave flattening)
  • Paralysis (in severe cases) 1

Diagnostic Approach

1. Measure serum potassium
2. Check spot urine potassium and creatinine
   • Urinary K+ >20 mEq/day with hypokalemia suggests renal potassium wasting
   • Urinary K+ <20 mEq/day suggests extrarenal losses 4, 3
3. Evaluate acid-base status
4. Consider measuring serum magnesium (hypomagnesemia can cause refractory hypokalemia) 1

Treatment of Hypokalemia

Urgent Treatment Indications

• Serum K+ ≤2.5 mEq/L
• ECG abnormalities
• Neuromuscular symptoms
• Cardiac ischemia
• Digitalis therapy 2, 6

Treatment Algorithm

1. Mild Hypokalemia (K+ 3.0-3.5 mEq/L)

• Oral potassium supplements (potassium chloride preferred)
• Typical dose: 40-80 mEq/day in divided doses 7
• Address underlying cause (adjust diuretic dose if possible) 1

2. Moderate Hypokalemia (K+ 2.5-3.0 mEq/L)

• Oral potassium chloride 60-120 mEq/day in divided doses
• Monitor serum potassium levels regularly
• Correct magnesium deficiency if present 1, 6

3. Severe Hypokalemia (K+ <2.5 mEq/L) or Symptomatic

• Intravenous potassium chloride
• Rate: 10-20 mEq/hour (maximum 40 mEq/hour in critical situations)
• Continuous cardiac monitoring required
• Frequent serum potassium measurements 5

Special Considerations

Metabolic Alkalosis

• Use potassium chloride (not other potassium salts) 7

Hypomagnesemia

• Correct magnesium deficiency to enable potassium correction
• IV magnesium sulfate initially, then oral magnesium oxide 1

Heart Failure Patients

• Potassium-sparing diuretics may be considered if hypokalemia persists despite ACE inhibitor therapy 1
• Monitor for hyperkalemia when combining potassium supplements with ACE inhibitors or potassium-sparing diuretics 1

Prevention Strategies

1. Regular monitoring of serum potassium in high-risk patients (those on diuretics, digitalis)
2. Use lowest effective dose of potassium-wasting diuretics
3. Consider combination with potassium-sparing diuretics when appropriate
4. Adequate dietary potassium intake (WHO recommends at least 3,510 mg/day) 2

Important Cautions

• Avoid rapid IV potassium administration (risk of cardiac arrest)
• Solid oral potassium supplements can cause GI ulceration; use liquid or effervescent preparations when possible 7
• Monitor for rebound hyperkalemia, especially with transcellular shifts 5
• Potassium-sparing diuretics should only be used when hypokalemia persists despite ACE inhibitor therapy 1