A 52-year-old woman with bipolar disorder type I has been on lithium carbonate 900 mg daily for 3 years with good mood stabilization. She presents to the emergency department with confusion, coarse tremor, ataxia, and diarrhea for the past 8 hours. Her family reports she had gastroenteritis 2 days ago and has been taking over-the-counter ibuprofen 400 mg three times daily for abdominal pain. On examination, she is disoriented to time and place, with hyperreflexia and nystagmus. Serum lithium level is 2.8 mEq/L (normal therapeutic range: 0.6–1.2 mEq/L). Serum creatinine is 1.4 mg/dL (baseline 0.9 mg/dL). What is the most appropriate immediate management?

Explanation

## Acute Lithium Toxicity Management **Key Point:** This patient has acute lithium toxicity (severe: lithium level >2.5 mEq/L) with CNS symptoms (confusion, ataxia, nystagmus) and neuromuscular signs (coarse tremor, hyperreflexia). The precipitant is NSAIDs (ibuprofen) combined with volume depletion from gastroenteritis, both of which reduce renal lithium clearance. ### Immediate Management Steps 1. **Discontinue lithium immediately** — no further doses 2. **Aggressive fluid resuscitation** — IV normal saline (0.9%) to restore intravascular volume and promote renal clearance 3. **Gastric decontamination** — gastric lavage (not activated charcoal, which does not bind lithium effectively) 4. **Supportive care** — monitor airway, breathing, circulation; seizure precautions 5. **Serial monitoring** — serum lithium levels (repeat at 4–6 hours), electrolytes, renal function, ECG **High-Yield:** NSAIDs and thiazide diuretics are the most common drug-drug interactions that precipitate lithium toxicity by reducing renal clearance. ACE inhibitors also increase lithium levels. **Clinical Pearl:** Lithium has a narrow therapeutic index (0.6–1.2 mEq/L). Levels >1.5 mEq/L cause toxicity; >2.5 mEq/L is life-threatening. Symptoms correlate poorly with serum levels in chronic toxicity but are more reliable in acute toxicity. ### Why Other Options Are Incorrect | Management | Rationale for Rejection | |---|---| | **Activated charcoal** | Lithium is an ion; charcoal does not adsorb it. Gastric lavage is the decontamination method of choice. | | **Lithium-specific Fab fragments** | These are not available in most centres and are reserved for extreme cases with refractory seizures or cardiac arrhythmias; not first-line. | | **Reduce dose + add thiazide** | Thiazides WORSEN lithium toxicity by reducing renal clearance (paradoxical effect). Continuing any lithium during acute toxicity is contraindicated. | **Mnemonic — Lithium Toxicity Triggers: SAND** - **S** — Salt depletion (dehydration, diarrhea, vomiting) - **A** — ACE inhibitors, NSAIDs - **N** — Nephrogenic diabetes insipidus (chronic lithium effect) - **D** — Diuretics (thiazides, loop) ### Hemodialysis Consideration Hemodialysis is indicated if: - Serum lithium >4 mEq/L - Severe neurological symptoms (seizures, coma, arrhythmias) - Acute renal failure - Altered mental status unresponsive to supportive care This patient's level (2.8 mEq/L) with severe symptoms warrants aggressive IV hydration and close monitoring; dialysis may be needed if symptoms worsen or level does not fall. [cite:Kaplan & Sadock's Synopsis of Psychiatry 12e Ch 32]