What are the implications and management of a lithium level of 1.9 in an adult patient with a history of bipolar disorder?

Lithium Level of 1.9: Critical Toxicity Requiring Immediate Emergency Management

A lithium level of 1.9 mEq/L represents severe toxicity requiring immediate discontinuation of lithium, emergency department evaluation, aggressive hydration, and potentially hemodialysis. 1

Immediate Clinical Actions

Stop lithium immediately and do not administer any further doses until the patient is medically cleared and lithium levels normalize. 1

Emergency Assessment Required

• Send the patient to the emergency department immediately for evaluation of lithium toxicity, as levels above 1.5 mEq/L are associated with severe toxicity even in patients who typically tolerate lithium well. 1
• Assess for signs of severe toxicity including coarse tremor (not just fine tremor), confusion, ataxia, seizures, cardiac arrhythmias, and altered mental status. 2, 3
• Evaluate hydration status immediately, as dehydration significantly increases lithium toxicity risk. 3
• Check renal function (BUN, creatinine) emergently, as impaired renal function can precipitate and worsen lithium toxicity. 2

Emergency Management Protocol

• Aggressive IV hydration with normal saline is the cornerstone of initial management to enhance renal lithium clearance. 3
• Hemodialysis should be considered for levels above 2.5 mEq/L, severe symptoms at any level, or renal impairment preventing adequate clearance. 3
• Monitor cardiac rhythm continuously, as lithium toxicity can cause life-threatening arrhythmias. 4
• Serial lithium levels should be drawn every 4-6 hours until declining and the patient is clinically improving. 1

Contributing Factors to Investigate

Medication and Medical Causes

• Review all medications for drug interactions, particularly NSAIDs (ibuprofen, naproxen), ACE inhibitors, thiazide diuretics, and loop diuretics, which can all increase lithium levels. 4
• Assess for dehydration from vomiting, diarrhea, excessive sweating, or inadequate fluid intake. 3
• Evaluate for acute kidney injury or chronic kidney disease progression. 2, 4
• Consider whether the patient took extra doses intentionally or accidentally. 2

Dosing Error Assessment

• Verify the prescribed lithium dose and compare to what the patient has actually been taking. 1
• Check if the patient switched from extended-release to immediate-release formulation without dose adjustment. 1

Post-Acute Management Strategy

When to Restart Lithium

• Do not restart lithium until the level is below 0.6 mEq/L and all toxicity symptoms have completely resolved. 1
• When restarting, reduce the dose by at least 50% from the previous regimen. 1
• Check lithium level 5 days after restarting at the new dose, then twice weekly until stable in the therapeutic range of 0.8-1.0 mEq/L for acute treatment or 0.6-1.0 mEq/L for maintenance. 1, 5

Alternative Mood Stabilizer Consideration

If this toxicity episode resulted from medication non-adherence, dosing errors, or recurrent toxicity issues, consider transitioning to valproate or an atypical antipsychotic (aripiprazole, olanzapine, quetiapine) which do not require the same narrow therapeutic monitoring. 2, 6

Critical Monitoring After Resolution

• Renal function must be reassessed 1-2 weeks after the toxic episode and then every 3-6 months indefinitely, as lithium toxicity can cause permanent nephropathy. 2, 4
• Thyroid function should be rechecked, as acute toxicity can worsen lithium-induced hypothyroidism. 2, 4
• Implement third-party medication supervision if this was an intentional overdose or if the patient has suicide risk. 2

Common Pitfalls to Avoid

• Never assume the patient can safely continue lithium at a reduced dose without complete medical evaluation—levels of 1.9 mEq/L can cause permanent organ damage. 4
• Do not restart lithium at the same dose after levels normalize—this will immediately cause recurrent toxicity. 1
• Avoid prescribing NSAIDs or other interacting medications to patients on lithium without considering the interaction. 4
• Do not rely solely on the lithium level—clinical toxicity symptoms may persist even as levels decline due to intracellular lithium accumulation. 1

Long-Term Implications

• Patients who experience severe lithium toxicity (>1.5 mEq/L) have increased risk of chronic kidney disease and require indefinite renal monitoring every 3-6 months. 4
• Consider whether this patient is an appropriate candidate for long-term lithium therapy, particularly if adherence, hydration maintenance, or medication management is problematic. 3
• If lithium is continued, maintain levels at the lower end of the therapeutic range (0.6-0.8 mEq/L) for maintenance therapy to minimize toxicity risk while preserving efficacy. 5