A 78-year-old woman with major depressive disorder was start… | MyMerci
Medical EmergenciesPA
Question
A 78-year-old woman with major depressive disorder was started on escitalopram 10 mg PO daily 2 weeks ago. She reports new headache, nausea, and confusion, and her family says she fell once at home. Today her serum sodium is 124 mEq/L (previously 138). Which action should the nurse take FIRST?
1Add hydrochlorothiazide to manage edema and continue escitalopram at the same dose.
2Double the escitalopram dose because depression often presents with somatic symptoms.
3Administer 250 mL of 0.9% normal saline as a rapid IV bolus to correct sodium quickly.
4Hold the escitalopram, notify the prescriber, restrict free water, and recheck serum sodium per orders.✓ Correct answer
Explanation
SIADH-related hyponatremia is a recognized adverse effect of SSRIs, especially in older adults, women, low body weight, and those on diuretics; it usually appears within 2–4 weeks of starting therapy. Symptoms reflect cerebral edema (headache, nausea, confusion, falls, seizures at very low Na). Priority is to hold the offending drug, notify the prescriber, and implement fluid restriction while monitoring sodium and neurologic status. Adding a thiazide worsens hyponatremia. Doubling the dose increases the risk. Rapid IV NS bolus risks osmotic demyelination and is not first-line; correction should be slow (≤8–10 mEq/L per 24 h).
In-depth explanation
Older adults on a new SSRI presenting with confusion or a fall need immediate sodium check and drug review — not symptom dismissal as "depression" or "aging".
Clinical scenario
Scenario A 78-year-old woman with MDD started escitalopram 10 mg PO daily 2 weeks ago. She now has headache, nausea, confusion, and one witnessed fall. Vital signs: BP 118/68, HR 82, RR 18, T 36.8°C. Labs: Na 124 mEq/L (baseline 138), K 4.1, Cr 0.8, urine osmolality 480 mOsm/kg, serum osmolality 262 mOsm/kg, urine Na 60 mEq/L → consistent with SIADH. No signs of dehydration or volume overload. Home meds: escitalopram, atorvastatin, calcium-vitamin D.
Key concepts
SIADH — Syndrome of Inappropriate ADH — euvolemic hyponatremia with concentrated urine (UOsm > SOsm) and elevated urine Na; SSRI/SNRI/carbamazepine/cyclophosphamide are common drug triggers. Treat by removing the trigger and restricting free water (~800–1000 mL/day).
Osmotic demyelination — Central pontine myelinolysis from correcting chronic hyponatremia faster than 8–10 mEq/L per 24 h; presents days later with dysarthria, dysphagia, paraparesis, and locked-in syndrome. Use slow correction; reserve hypertonic saline for severe symptomatic cases.
SSRI elderly cautions — Older adults are at higher risk of SSRI-related hyponatremia, falls (orthostasis, sedation), GI bleeding (especially with NSAIDs), and QT prolongation (citalopram has an FDA dose limit of 20 mg in age >60). Baseline Na, ECG, and review of polypharmacy are recommended.