Lithium Toxicity — Fluids and Dialysis

Key Points

• Clinical severity depends on exposure pattern and tissue burden, not simply the serum lithium concentration.
• Chronic toxicity can produce severe neurologic symptoms at lower concentrations than acute ingestion.
• Volume depletion, renal impairment, thiazides, ACE inhibitors, ARBs, and NSAIDs are common causes of accumulation.
• Activated charcoal does not adsorb lithium.
• Isotonic saline is the cornerstone of supportive treatment in volume-depleted patients.
• Serial lithium concentrations are mandatory because delayed peaks and post-dialysis rebound can occur.
• Hemodialysis is the preferred extracorporeal treatment for severe lithium poisoning.
• After dialysis, continue levels for at least 12 hours to detect rebound and determine whether additional treatment is needed.

Algorithm

1. Stop lithium and obtain exposure history, formulation, dose, timing, chronic use, renal function, and interacting medications.
2. Assess neurologic status, volume status, airway, ECG, urine output, and signs of nephrogenic diabetes insipidus.
3. Obtain lithium concentration, electrolytes, renal function, glucose, ECG, and pregnancy testing when relevant.
4. Give isotonic saline for volume depletion and correct sodium or other electrolyte abnormalities carefully.
5. Obtain serial lithium concentrations until a consistent decline is demonstrated.
6. Consider whole bowel irrigation for a major sustained-release ingestion with a protected airway and no contraindication.
7. Consult nephrology and toxicology early for significant symptoms, renal impairment, very high concentration, or slow predicted clearance.
8. Initiate hemodialysis for severe neurologic or cardiac toxicity or when EXTRIP concentration and renal criteria are met.
9. After dialysis, repeat lithium concentrations for at least 12 hours to assess rebound.
10. Do not restart lithium until the cause of toxicity, renal function, interacting drugs, and psychiatric treatment plan have been reassessed.

Clinical Synopsis & Reasoning

Lithium has a narrow therapeutic index and is eliminated almost entirely by the kidneys. Toxicity occurs after acute ingestion, chronic accumulation, or an acute ingestion on top of chronic therapy. These patterns matter because serum concentration and tissue burden do not align perfectly. In an acute ingestion by a lithium-naive patient, a high early serum concentration can precede tissue distribution and neurologic toxicity. In chronic toxicity, substantial neurologic symptoms can occur at lower concentrations because the brain has already equilibrated with lithium.

Early symptoms include nausea, vomiting, diarrhea, coarse tremor, weakness, and lethargy. Progressive neurotoxicity causes ataxia, dysarthria, confusion, agitation, myoclonus, hyperreflexia, seizures, and coma. Severe cases can produce dysrhythmias, nephrogenic diabetes insipidus, hypernatremia, renal injury, and prolonged encephalopathy. The syndrome of irreversible lithium-effectuated neurotoxicity is uncommon but underscores the importance of avoiding prolonged severe neurologic exposure.

Volume depletion is a common trigger because the kidney reabsorbs lithium along with sodium in the proximal tubule. Thiazide diuretics, ACE inhibitors, angiotensin receptor blockers, and NSAIDs can increase lithium concentrations by reducing renal clearance. Acute kidney injury, chronic kidney disease, low sodium intake, vomiting, diarrhea, fever, and dehydration also increase risk. A detailed medication and volume-status history is therefore essential.

Serum lithium must be followed serially. A single concentration does not define severity or disposition. Extended-release tablets can form pharmacobezoars and cause delayed or recurrent peaks. After dialysis, lithium can rebound as drug redistributes from tissues into plasma, which is why post-dialysis levels require continued surveillance.

Treatment Strategy & Disposition

Stop lithium and all drugs that reduce its clearance. Stabilize airway and circulation, treat seizures with standard benzodiazepine therapy, and correct clinically important electrolyte abnormalities. In most volume-depleted patients, isotonic saline is the first-line treatment because restoration of renal perfusion and sodium delivery increases lithium excretion. Avoid forced diuresis and avoid creating hypernatremia through uncontrolled saline administration. Measure urine output and watch for nephrogenic diabetes insipidus.

Activated charcoal does not bind lithium and has no role in isolated lithium ingestion. Whole bowel irrigation can be considered after a substantial acute ingestion of sustained-release lithium when the airway is protected and there is no ileus or obstruction, ideally with toxicology guidance. Serial lithium concentrations are generally obtained every few hours until a clear downward trend is established and the clinical picture is improving.

Hemodialysis is the definitive way to remove lithium in severe poisoning because lithium is small, water soluble, minimally protein bound, and has a low volume of distribution. EXTRIP recommends extracorporeal treatment when kidney function is impaired and lithium is above a high threshold, and in the presence of severe neurologic or cardiac toxicity such as decreased consciousness, seizures, or life-threatening dysrhythmia regardless of concentration. Dialysis is also suggested at very high concentrations or when confusion is significant or the expected time to fall below a safe level with optimal therapy is prolonged. Intermittent hemodialysis is preferred because it clears lithium rapidly.

Continue dialysis until there is substantial clinical improvement or lithium is below the recommended stopping threshold, then obtain serial concentrations for at least 12 hours to detect rebound. Repeated hemodialysis may be necessary. Continuous renal replacement therapy is less efficient but can be used when intermittent hemodialysis is unavailable or as a strategy after initial dialysis in selected unstable patients. Nephrology, toxicology, and critical care consultation should occur early in any patient who may meet extracorporeal treatment criteria.

Epidemiology / Risk Factors

• Lithium remains an effective maintenance treatment for bipolar disorder and has important anti-suicide benefits, but its narrow therapeutic index requires monitoring.
• Chronic toxicity is frequently precipitated by dehydration, acute illness, kidney injury, or a newly added interacting medication.
• Older adults are at higher risk because renal reserve and total-body water decline with age.
• Intentional acute ingestion can produce very high serum concentrations before severe neurologic symptoms develop.
• Patients with chronic exposure plus an acute ingestion may develop both high concentrations and substantial tissue burden.

Investigations

Common Triggers of Toxicity

Pharmacology

Prognosis / Complications

• Most patients recover with prompt volume restoration and dialysis when indicated.
• Prolonged severe neurologic toxicity increases the risk of persistent deficits.
• Renal dysfunction and delayed recognition can prolong lithium exposure and hospitalization.
• Post-dialysis rebound is common enough that serial monitoring is required even after a successful treatment session.
• Long-term outcome is improved by correcting the medication, renal, and hydration factors that caused the episode.

Patient Education / Counseling

• Explain the importance of maintaining hydration during heat exposure, vomiting, diarrhea, or febrile illness.
• Before starting NSAIDs, ACE inhibitors, ARBs, or diuretics, patients taking lithium should check with the prescribing clinician.
• Keep scheduled lithium and renal-function monitoring appointments.
• Seek urgent care for new coarse tremor, marked unsteadiness, confusion, severe vomiting, slurred speech, or unusual drowsiness.
• Do not change salt intake dramatically without discussing it with the prescriber because sodium balance affects lithium handling.
• After toxicity, restart decisions should be made jointly by psychiatry and the medical team after renal function and interacting medications are reviewed.

Notes

Lithium poisoning is a classic example of why toxicology requires pattern recognition rather than treatment to a number. A high early level after an acute ingestion can precede symptoms, while a lower level in chronic toxicity can accompany profound neurotoxicity. Serial examination and serial concentrations are therefore inseparable.

EXTRIP recommendations support intermittent hemodialysis as the preferred extracorporeal treatment and emphasize continued post-treatment levels because lithium can rebound after redistribution from tissues.

References

1. EXTRIP Workgroup: Lithium Recommendations — Link