Electrolyte Imbalances for NCLEX: Sodium, Potassium, Calcium & Magnesium

Electrolyte Imbalances: Essential NCLEX Review

Electrolyte imbalance questions appear across multiple NCLEX categories including pharmacology, physiological adaptation, and reduction of risk. Mastering electrolyte normal ranges, signs and symptoms, and nursing interventions is critical for exam success.

Sodium Imbalances

Hyponatremia (below 136 mEq/L): Causes include SIADH, excessive water intake, diuretics, and vomiting or diarrhea. Signs and symptoms include nausea, headache, confusion, seizures, and coma in severe cases. Nursing interventions include fluid restriction for dilutional hyponatremia, administering hypertonic saline (3% NS) cautiously for severe cases, and monitoring neurological status. Correct slowly to prevent osmotic demyelination syndrome. Hypernatremia (above 145 mEq/L): Causes include dehydration, diabetes insipidus, and excessive sodium intake. Signs include thirst, dry mucous membranes, restlessness, and altered mental status. Interventions include administering hypotonic fluids and monitoring for fluid overload during correction.

Potassium Imbalances

Hypokalemia (below 3.5 mEq/L): Common causes include diuretics (loop and thiazide), vomiting, diarrhea, and alkalosis. Signs include muscle weakness, fatigue, leg cramps, decreased bowel sounds, and cardiac arrhythmias (flattened T waves, U waves). Replace potassium IV at no more than 10-20 mEq per hour with cardiac monitoring. Never give potassium IV push. Hyperkalemia (above 5.0 mEq/L): Causes include renal failure, ACE inhibitors, potassium-sparing diuretics, and acidosis. Signs include muscle weakness, paresthesias, and cardiac arrhythmias (peaked T waves, widened QRS). Emergency treatment includes IV calcium gluconate (cardioprotective), insulin with glucose (shifts potassium intracellularly), sodium bicarbonate, and kayexalate (eliminates potassium via GI tract).

Calcium Imbalances

Hypocalcemia (below 9.0 mg/dL): Causes include hypoparathyroidism, vitamin D deficiency, and pancreatitis. Assess for Trousseau sign (carpal spasm with BP cuff inflation) and Chvostek sign (facial twitching when tapping facial nerve). Seizure precautions are essential. Hypercalcemia (above 10.5 mg/dL): Causes include hyperparathyroidism and malignancy. Signs include muscle weakness, constipation, kidney stones, and cardiac arrhythmias. Hydration and calcitonin are initial treatments.

Magnesium

Hypomagnesemia causes similar symptoms to hypocalcemia and hypokalemia. Hypermagnesemia causes respiratory depression and hypotension. Monitor deep tendon reflexes as a clinical indicator. Review with our clinical nursing mini-exams and electrolyte cheat sheets.