A client taking carbamazepine develops confusion and unsteady gait. The serum sodium is 121 mEq/L. Which action should the nurse take?
1Give the scheduled carbamazepine and encourage unrestricted free-water intake.
2Hold carbamazepine, notify the provider urgently, and institute seizure and fall precautions.✓ Correct answer
3Administer hypotonic IV fluid and reassess the sodium at the next clinic visit.
4Encourage independent ambulation because movement corrects dilutional hyponatremia.
Explanation
Carbamazepine can cause SIADH and hyponatremia. Sodium 121 mEq/L with confusion and unsteady gait is symptomatic and requires the medication to be held, urgent clinical evaluation, and seizure and fall precautions. The prescriber determines discontinuation and sodium correction based on severity and chronicity. Free water and hypotonic fluid can worsen dilutional hyponatremia, and independent ambulation is unsafe.
Clinical reasoning Carbamazepine-associated SIADH retains free water and lowers serum sodium. Neurologic symptoms signal clinically important cerebral effects and increase seizure and injury risk.
Decision rule Hold the suspected medication, escalate symptomatic severe hyponatremia urgently, protect the client from seizures and falls, and avoid unprescribed rapid correction.
Scenario 58-year-old male on carbamazepine 400 mg PO BID × 6 weeks reports headache, mild confusion, and decreased urine output. Serum sodium 126 mEq/L (low).
SIADH — Excess antidiuretic effect that retains free water and can produce dilutional hyponatremia with neurologic symptoms.
Symptomatic hyponatremia — Low serum sodium accompanied by manifestations such as confusion, weakness, gait instability, or seizures that requires urgent evaluation.
Carbamazepine adverse effects — SIADH, agranulocytosis, hepatotoxicity, SJS, and CYP3A4 autoinduction — all require monitoring.