A -year-old woman is admitted to the intensive care unit with profound lethargy, confusion, and a generalized tonic-clonic seizure. She has a history of hypertension for which chlorthalidone was prescribed two weeks ago. On admission (Hour 0), her serum sodium concentration is mEq/L. A 3% sodium chloride infusion is initiated. Six hours later, her mental status improves, and the infusion rate is reduced by half. The following morning (Hour 12), the patient is alert and oriented. The nurse notes a significant increase in urine output to approximately mL/hr over the past three hours.
| Time elapsed | Serum sodium | Clinical status |
|---|---|---|
| Hour 0 | mEq/L | Unresponsive, generalized seizure |
| Hour 6 | mEq/L | Lethargic but arousable, no further seizures |
| Hour 12 | mEq/L | Alert, oriented, large volume diuresis noted |
Which of the following is the best next step in the management of this patient?
- Discontinue the 3% sodium chloride and administer 5% dextrose in water with intravenous desmopressinAnswer
- BDiscontinue the 3% sodium chloride and institute strict fluid restriction
- CContinue the current infusion and recheck the serum sodium level in 4 hours
- DSwitch the infusion to 0.9% sodium chloride and administer intravenous furosemide
- EMaintain current therapy and obtain an urgent magnetic resonance imaging of the brain
Answer
Discontinue the 3% sodium chloride and administer 5% dextrose in water with intravenous desmopressin.
The correct answer requires recognizing that the patient is experiencing a dangerously rapid overcorrection of severe hyponatremia. The maximum safe correction limit is mEq/L in a -hour period for patients at high risk of osmotic demyelination syndrome (such as those with thiazide-induced severe hyponatremia). This patient has already corrected by mEq/L in just hours. The large volume of dilute urine indicates 'auto-correction' due to the washout of the thiazide diuretic. To prevent osmotic demyelination syndrome, the hypertonic saline must be stopped immediately, and free water (5% dextrose in water) along with a vasopressin analogue (intravenous desmopressin) must be administered to actively re-lower the serum sodium level to safe limits.
Step-by-Step Solution
Key Concept
Management of rapid overcorrection in severe hyponatremia requires immediately stopping hypertonic saline and administering D5W with desmopressin to re-lower the serum sodium and prevent osmotic demyelination syndrome.