Lithium toxicity: when is hemodialysis necessary?

Unrecognized acute lithium toxicity: a case report

We report a case of a 63-year-old male who has been admitted to the Emergency department with nonspecific symptoms. Lithium toxicity was not at first recognized. When we obtained sufficient information about previous medication and medical history, we measured lithium levels found to be 1.46 mmol/L. Although the value of lithium was mildly elevated, nephrotoxicity was produced leading to severe renal insufficiency and neurological symptoms. Hemodialysis was started, and we succeed to treat the patient without squeals. This case illustrates some of the factors that lead to lithium toxicity as well as the need to consider lithium toxicity to the differential diagnosis of a patient presenting with renal insufficiency with or without change in mental status and neurologic symptom.

Evaluation of available treatment guidelines for the management of lithium intoxication

Intoxications with lithium carry considerable risk for long-term morbidity and even mortality. Consequently, any patient suspected of lithium intoxication requires immediate and appropriate care. The objectives of this study were to assess the completeness and the applicability of generally available treatment guidelines for the management of patients with a lithium intoxication and, hence, to provide general recommendations for improvement of existing treatment guidelines. Nineteen treatment guidelines originating from 7 different countries were gathered by searching the Internet, online databases, and textbooks and by contacting different poison information centers and university medical centers. A list of items was composed from the retrieved treatment guidelines and a further literature search. Most relevant items were present in the various guidelines. However, in some guidelines, essential information was missing or potentially hazardous information was provided. Clarity, presentation, and applicability of the guidelines, as assessed using parts of the Appraisal of Guidelines Research and Evaluation instrument, were relatively poor. Regular updates of treatment guidelines should be performed to incorporate new essential information. To improve applicability of guidelines, unambiguous key recommendations, alternative treatments, and special care requirements should be provided and authors are recommended to test treatment guidelines using a panel of less experienced caregivers in a hypothetical case scenario.

Management of Lithium Toxicity

Lithium salts have been used in the prophylaxis and treatment of depression and bipolar disorder for >50 years. Lithium has a narrow therapeutic range, and several well characterised adverse effects limit the potential usefulness of higher doses. Acute ingestion in lithium-naive patients is generally associated with only short-lived exposure to high concentrations, due to extensive distribution of lithium throughout the total body water compartment. Conversely, chronic toxicity and acute-on-therapeutic ingestion are associated with prolonged exposure to higher tissue concentrations and, therefore, greater toxicity. Lithium toxicity may be life threatening, or result in persistent cognitive and neurological impairment. Therefore, enhanced lithium clearance has been explored as a means of minimising exposure to high tissue concentrations. Although haemodialysis is highly effective in removing circulating lithium, serum concentrations often rebound so repeated or prolonged treatment may be required. Continuous arteriovenous haemodiafiltration and continuous venovenous haemodiafiltration increase lithium clearance, albeit to a lesser extent than haemodialysis, and are more widely accessible. Haemodiafiltration sustained for >16 hours allows effective removal of total body lithium, thereby avoiding rebound effects. Enhanced elimination should be considered in patients at greatest risk of severe poisoning: namely those with chronic or acute-on-therapeutic toxicity, those with clinically significant features, and those with chronic toxicity whose serum lithium concentration is >2.5 mmol/L. The choice between haemodialysis and continuous haemodiafiltration techniques will depend on local accessibility and urgency of enhancing lithium elimination. Further research is required to establish the potential benefits of assisted elimination on clinical outcome in patients with lithium poisoning.

Methods used to decrease lithium absorption or enhance elimination

OBJECTIVE

To review current methods, well documented and investigational, being used to decrease lithium absorption or enhance lithium elimination.

METHODS

The basic science and clinical literature on lithium were reviewed by a comprehensive Medline search from 1984 to 1996. Additional references were identified by reviewing the reference citations from the results of the Medline search.

RESULTS

Prevention of Absorption: Whole bowel irrigation has been demonstrated to be an effective means of enhancing lithium removal from the gastrointestinal tract. Sodium polystyrene sulfonate resin administration has been shown to be effective in binding lithium elimination in animal and human models. However, the lower limits of effective sodium polystyrene sulfonate dosing and the extent of potassium lowering in humans are questions that need to be answered before sodium polystyrene sulfonate resin can be recommended for routine, use. Enhancement of Elimination: Saline or forced diuresis is not effective in enhancing lithium elimination unless the patient is volume or sodium depleted. The use of continuous arteriovenous hemodiafiltration or low dose dopamine to enhance lithium elimination has only been documented in case reports. Intravenous aminophylline (theophylline) is not consistently effective and its risks outweigh possible benefits. The literature supports hemodialysis as a well documented and effective means of enhancing lithium elimination. Controversy exists over the appropriate indications for its initiation.

DISCUSSION

Given the wide interpatient variability in lithium pharmacokinetics, single case reports do not provide sufficient evidence of the effectiveness of a given method to enhance

Multiple delayed peak lithium concentrations following acute intoxication with an extended-release product

OBJECTIVE

To describe delayed peak lithium concentrations after an overdose of extended-release lithium tablets.

CASE SUMMARY

A patient with borderline personality disorder and depression ingested extended-release lithium approximately 20.25 g along with other agents. At presentation, the lithium concentration was 1.4 mEq/L. Significant enteral intake was initiated 27 hours after presentation and the lithium concentration 5 hours later increased to 3.2 mEq/L. A second lithium peak concentration of 5.0 mEq/L was noted 40 hours after presentation. Two hemodialysis sessions lasting 4 hours each were performed along with administration of sodium polystyrene sulfonate in sorbitol 20% to enhance lithium elimination and decrease absorption. Eighty-eight hours after presentation, the lithium concentration had decreased to 1.5 mEq/L.

DISCUSSION

Delayed and secondary peak lithium concentrations have been reported following an overdose with an extended-release product. Extended-release lithium may form an aggregate in the gastrointestinal tract and/or have delayed absorption secondary to coingested drugs. Toxicity may result if the patient begins enteral intake of drugs, fluids, or nutrition.

CONCLUSIONS

Continued monitoring of lithium concentrations after an acute ingestion with an extended-release product are recommended until lithium concentrations are less than 1.5 mEq/L and there are no signs of toxicity, particularly once the patient begins significant enteral intake.

In vitro binding of lithium using the cation exchange resin sodium polystyrene sulfonate

Sodium polystyrene sulfonate, a cation exchange resin, should be useful in the treatment of lithium overdosage. This in vitro study was conducted to assess the ability of sodium polystyrene sulfonate to bind lithium, effects of pH on binding, binding efficacy in comparison to charcoal, and affinity for lithium versus potassium. Stock solutions of lithium were added to fixed amounts of sodium polystyrene sulfonate and charcoal. Lithium and potassium concentrations in supernatant were measured by flame photometry. Increasing concentrations of sodium polystyrene sulfonate bound more lithium. Changes in pH had little effect on lithium binding. Lithium is bound to sodium polystyrene sulfonate more readily than to charcoal. Potassium is preferentially bound to sodium polystyrene sulfonate over lithium. Sodium polystyrene sulfonate may provide a useful therapeutic modality in the treatment of lithium overdosage.