Can hypokalemia (low potassium levels) mimic a stroke?

Hypokalemia as a Stroke Mimic

Yes, hypokalemia can mimic stroke symptoms and should be considered in the differential diagnosis of patients presenting with acute neurological deficits.

Neurological Manifestations of Hypokalemia

Hypokalemia can produce various neurological symptoms that may resemble stroke, particularly when potassium levels are severely low (<2.5 mEq/L). These manifestations include:

• Muscle weakness or paralysis
• Altered mental status
• Numbness and paresthesias
• Speech disturbances
• Facial weakness
• Eyelid weakness

Pathophysiology

The neurological symptoms of hypokalemia occur due to:

• Altered cell membrane excitability affecting neuromuscular function
• Changes in resting membrane potential
• Disruption of normal nerve impulse transmission
• Associated electrolyte abnormalities (particularly hypomagnesemia)

Diagnostic Considerations

When evaluating patients with suspected stroke:

• Hypoglycemia should be measured immediately as it can cause stroke-like symptoms that are readily reversible if corrected quickly 1
• Electrolyte panels, particularly potassium and magnesium levels, should be checked
• ECG changes associated with hypokalemia include T-wave flattening, ST-segment depression, prominent U waves, and prolonged QT interval 2
• Severe hypokalemia (<2.5 mEq/L) requires immediate attention due to risk of cardiac arrhythmias

Stroke Mimics in Clinical Practice

Approximately half of all in-hospital stroke alerts are ultimately determined to be stroke mimics 1. Common stroke mimics include:

• Toxic-metabolic encephalopathy
• Sedative medication effects (particularly opioids and benzodiazepines)
• Seizures
• Syncope
• Sepsis
• Electrolyte disturbances, including hypokalemia

Management Approach

For patients presenting with stroke-like symptoms:

1. Obtain immediate serum glucose measurement
2. Check electrolyte panel including potassium and magnesium
3. Obtain ECG to evaluate for changes consistent with hypokalemia
4. If hypokalemia is detected:
   • Mild (3.0-3.5 mEq/L): Oral potassium supplementation 20-60 mEq/day
   • Moderate (2.5-2.9 mEq/L): More aggressive oral replacement or consider IV replacement
   • Severe (<2.5 mEq/L): IV potassium replacement at up to 10 mEq/hour 2
5. Always check magnesium levels, as hypomagnesemia can perpetuate hypokalemia and make it resistant to treatment 2

Clinical Pearls and Pitfalls

• Altered mental status as the sole neurological symptom is most often a stroke mimic in hospitalized patients 1
• Hypokalemia and hypomagnesemia often coexist and should be corrected simultaneously
• Patients on digoxin are at higher risk of arrhythmias with hypokalemia 2
• Rapid correction of severe hypokalemia is necessary but must be done cautiously to avoid cardiac complications
• Chronic mild hypokalemia can accelerate progression of chronic kidney disease and increase mortality 3

Case Evidence

A case report describes a patient who presented with left facial numbness and eyelid weakness initially suspected to be a stroke but was found to have hypomagnesemia (1.50 mg/dL). The symptoms resolved after intravenous magnesium supplementation 4. This highlights the importance of considering electrolyte abnormalities in the differential diagnosis of stroke-like presentations.

In conclusion, hypokalemia should be considered in the differential diagnosis of patients presenting with stroke-like symptoms, particularly when symptoms include generalized weakness, paresthesias, or altered mental status. Prompt recognition and correction of electrolyte abnormalities can prevent unnecessary interventions and lead to rapid symptom resolution.