What electrolyte abnormalities can cause flaccid quadriparesis?

Electrolyte Abnormalities Causing Flaccid Quadriparesis

The primary electrolyte abnormalities that cause flaccid quadriparesis are hyperkalemia and hypokalemia, with hyperkalemia being particularly dangerous as it can rapidly progress to cardiac arrest. 1

Hyperkalemia

Severe hyperkalemia (>6.5 mmol/L) is a life-threatening cause of flaccid quadriparesis that requires immediate recognition and treatment. 1

Clinical Presentation

• Flaccid paralysis is a cardinal manifestation of severe hyperkalemia, often accompanied by paresthesias of the extremities, depressed deep tendon reflexes, and respiratory difficulties. 1
• The first clinical indicator may be ECG changes showing peaked T waves, which can progress to flattened P waves, prolonged PR interval, widened QRS complex, and ultimately sine-wave pattern leading to cardiac arrest. 1
• Hyperkalemia most commonly occurs from renal failure or release of potassium from cells. 1

Management Priority

For cardiac arrest or severe cardiotoxicity from hyperkalemia, IV calcium must be administered immediately in addition to standard ACLS care. 1

The treatment sequence is:

1. Stabilize myocardial membrane: Calcium chloride 10% (5-10 mL IV over 2-5 minutes) or calcium gluconate 10% (15-30 mL IV over 2-5 minutes) 1
2. Shift potassium into cells: Sodium bicarbonate 50 mEq IV over 5 minutes, glucose (25g) plus insulin (10 U regular) IV over 15-30 minutes, or nebulized albuterol 10-20 mg over 15 minutes 1
3. Promote excretion: Furosemide 40-80 mg IV, Kayexalate 15-50g, or dialysis 1

Critical Pitfall

IV bolus administration of potassium for cardiac arrest in suspected hypokalemia is NOT recommended as it can be harmful. 1

Hypokalemia

Severe hypokalemia causes flaccid quadriparesis through altered cardiac and skeletal muscle excitability. 2, 3, 4, 5

Clinical Features

• Potassium depletion manifests as weakness, fatigue, cardiac rhythm disturbances, prominent U-waves on ECG, and in advanced cases, flaccid paralysis and impaired ability to concentrate urine. 2
• Hypokalemia typically occurs with diuretic therapy, hyperaldosteronism, diabetic ketoacidosis, severe diarrhea with vomiting, or inadequate replacement during parenteral nutrition. 2
• The intoxication signs from potassium phosphate include paresthesias of extremities, flaccid paralysis, listlessness, mental confusion, weakness and heaviness of legs, and cardiac arrhythmias. 3

Associated Conditions

• Thyrotoxic periodic paralysis can present with rapid onset flaccid quadriparesis associated with severe hypokalemia (as low as 1.5 mmol/L) and hypophosphatemia. 4
• Distal renal tubular acidosis (dRTA), particularly associated with primary Sjögren's syndrome, causes recurrent hypokalemia leading to flaccid quadriparesis in fewer than 2% of Sjögren's cases. 5, 6

Management Approach

• Correct the underlying cause (e.g., discontinue diuretics, treat diarrhea). 2
• Replace potassium with high-potassium foods or potassium chloride supplements when metabolic alkalosis is present. 2
• In metabolic acidosis with hyperchloremia (e.g., renal tubular acidosis), use potassium salts other than chloride such as potassium bicarbonate, citrate, acetate, or gluconate. 2

Hypophosphatemia

Severe hypophosphatemia (<0.32 mmol/L) contributes to respiratory failure and prolonged mechanical ventilation but is less commonly a direct cause of quadriparesis compared to potassium abnormalities. 1

• Hypophosphatemia occurs in 60-80% of ICU patients, particularly with intensive kidney replacement therapy and refeeding syndrome. 1
• Associated with worsening respiratory failure, cardiac arrhythmias, and prolonged hospitalization. 1

Hypomagnesemia

Hypomagnesemia (<0.70 mmol/L) prolongs the QT interval and can lead to ventricular arrhythmias but typically does not cause isolated flaccid quadriparesis. 1

• Occurs in up to 60-65% of critically ill patients, particularly with kidney replacement therapy using citrate anticoagulation. 1
• For cardiac arrest from severe hypomagnesemia, IV magnesium is recommended in addition to standard ACLS care. 1

Key Monitoring Recommendations

Electrolytes must be closely monitored in hospitalized patients with kidney disease receiving kidney replacement therapy, as electrolyte abnormalities occur in up to 65% of critically ill patients. 1

• Focus monitoring on phosphate, potassium, and magnesium. 1
• Use dialysis solutions containing potassium, phosphate, and magnesium to prevent electrolyte disorders during kidney replacement therapy. 1