Sodium (Na+) on the NCLEX
Hyponatremia and hypernatremia: causes, signs, correction rules.
Sodium 135-145. Imbalances are common and dangerous if corrected too fast.
Hyponatremia (<135)
Causes: SIADH, diuretics, HF, cirrhosis, water intoxication, hyperglycemia (pseudohyponatremia). Signs: confusion, nausea, seizures, coma at severe (<120). Treatment: identify cause. Mild: fluid restriction. Severe symptomatic: hypertonic saline (3%) cautiously. Correct slowly, no more than 8-12 mEq/24h (risk: central pontine myelinolysis).
Hypernatremia (>145)
Causes: dehydration, DI, hyperaldosteronism. Signs: thirst, lethargy, irritability, seizures. Treatment: replace water deficit slowly. Hypotonic fluid (D5W or 0.45% NS). Correct over 48-72h to avoid cerebral edema.
Frequently asked
Why correct sodium slowly?
Rapid correction → osmotic shifts → brain damage. Either way (hypo or hyper).
SIADH treatment?
Fluid restriction first. Demeclocycline or tolvaptan in chronic.
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