THE CASE

A 30-year-old female with a history of bipolar disorder presented after intentional lithium overdose. The patient reported feeling increasingly depressed for several weeks with intermittent suicidal thoughts. She reported getting into a verbal altercation with family while drinking alcohol and subsequently ingested a nearly full bottle of lithium (approximately 40 tablets, each with a concentration of 300 mg). She reported mild blurred vision and anxiety, but otherwise denied any other subjective complaints.

Vital signs were within normal limits. On exam, the patient appeared anxious, but otherwise non-toxic. Cardiopulmonary exam was normal. Abdominal exam was benign. Neurologic exam unremarkable. There was no clonus, muscular rigidity or ataxia appreciated on initial evaluation. 

Initial labs revealed mild hypokalemia to 3.3 MEQ/L with a normal anion gap and normal GFR. Initial lactate was mildly elevated at 2.0 MEQ/L. Lithium level returned elevated at 2.42 MEQ/L. EKG was notable for QRS of 105 milliseconds and a normal QTc. Poison control was contacted, and recommendations were followed. The patient was treated with an ampule of bicarbonate followed by a bicarbonate drip to treat QRS >100 milliseconds. Isotonic fluids were initiated at twice maintenance and whole bowel irrigation was initiated after placement of an NG tube. The patient was admitted to the MICU. Renal was consulted in anticipation of possible dialysis.

DIAGNOSIS

 Lithium overdose

DISCUSSION

 Overview of Lithium Use

Lithium is a well-known treatment for bipolar disorder. Prescribers and patients must be aware, however, that lithium has a very narrow therapeutic window and patients on chronic lithium maintenance are likely to have at least one episode of lithium toxicity in their lifetime. [1] In overdose, especially when intentional, lithium can be lethal. Emergency medicine (EM) physicians must first consider lithium toxicity as a potential cause of a patient’s presentation, and then be able to recognize signs of lithium toxicity and know how to effectively treat toxicity and prevent life threatening complications of lithium overdose.

Overview of Lithium Toxicity

Lithium toxicity can be divided into acute versus chronic toxicity. This blog post will focus mostly on the acute toxicity that can be seen in the emergency department and how to manage it. In order to determine and predict the extent of lithium toxicity, the EM provider must determine the ingested amount, approximate time of ingestion, and presence of any co-ingestions. [2]  

Signs and Symptoms of Acute Lithium Toxicity

Lithium toxicity does not always correlate to lithium blood levels. [3] Acute toxicity will often manifest as immediate gastrointestinal symptoms, while other symptoms tend to develop over several houses as lithium moves into cells and tissues throughout the body. Lithium toxicity can affect several vital organ systems, and manifest as a broad array of signs/symptoms. Neurologic sequelae of lithium toxicity can manifest as hyperreflexia, tremor, ataxia and nystagmus. Level of consciousness can range from mild confusion to severe delirium. Lithium can also have toxic effects on the endocrine system, leading to hypothyroidism through inhibition of thyroid hormone synthesis and release. Cardiovascular manifestations can be observed on EKG through t wave flattening, and patients can suffer from sinus node dysfunction, QT prolongation and intraventricular conduction delays. Lithium toxicity also affects the renal system and can impair the kidneys urine concentrating ability as well as can lead to nephrogenic diabetes insipidus. Patients may also demonstrate severe nausea and vomiting and vision changes when suffering from acute lithium toxicity. [2]

ED Work-Up

Patients with suspected lithium overdose should have close cardiopulmonary monitoring. An initial EKG should be obtained to determine baseline QRS and Qtc. Serum electrolytes, point-of-care glucose, lithium level and TSH should be obtained, along with Tylenol and salicylate levels and a urine drug screen to assess for co-ingestions. Normal serum lithium concentrations range from 0.6 to 1.2 mEq/L.

Prevention and Treatment of Lithium Toxicity

Unlike with many other ED presentations of drug overdose, there is no role for activated charcoal given lithium does not bind to activated charcoal. The caveat being if co-ingestion is suspected and the patient presents within an appropriate time-frame. [2]

Whole bowel irrigation, as used in this case, should be considered for all lithium overdoses, particularly in patients presenting early after their ingestion. When used appropriately, whole bowel irrigation can help avoid the need for dialysis later on in the patient’s hospital course. The next section will focus on how to initiate whole bowel irrigation in the ED.

Whole Bowel Irrigation For Decontamination

Whole bowel irrigation is less common, however remains a crucial treatment of choice for certain overdoses. The pneumonic “LIMPS” is a helpful reminder for some indications for use of whole bowel irrigation (lithium, iron, metals, packers/stuffers, sustained release drugs). [4] The procedure entails placement of a nasogastric (NG) tube and initiation of polyethylene glycol (PEG) through the NG until clear rectal effluent is achieved. In adults, it is recommended to instill 1.5-2 L of PEG per hour (1 L/hr for pediatrics age 6-12, 0.5 L/hr for pediatrics <6 years).

ED providers may need to be resourceful when obtaining the equipment to initiate whole bowel irrigation. In our case, we emptied a continuous bladder irrigation bag and filled it with PEG. We then were able to connect the CBI bag to the NG tube and secured it in place as depicted below.

Disposition

All patients with concern for lithium overdose as well as signs/symptoms of overdose should be admitted to the hospital for monitoring. Severe cases often end up in the ICU. Serial lithium levels should monitored until levels peak and begin to show a downward trend. Most guidelines recommend monitoring until lithium levels fall less than 1.5 mEq/L. [2]

CASE RESOLUTION

The patient was admitted to the ICU with renal following. She ultimately did not require dialysis. Whole bowel irrigation was well-tolerated and continued until clear rectal effluent was obtained. Lithium levels were trended to peak and began to down-trend within 24 hours. Her symptoms resolved and after a few days she was ultimately deemed medically clear and was admitted to inpatient psychiatry.

KEY TAKE-AWAYS

1. Lithium has a narrow therapeutic index, thus potential for toxicity is high.

2. Providers should maintain a high index of suspicion for lithium overdose and involve poison control or a toxicologist early.

3. Whole bowel irrigation is not used commonly but can be very effective in preventing downstream sequelae of lithium overdose, especially when implemented early.

Author: Michelle Myles, MD is a fourth year emergency medicine resident at Brown University.

Faculty Editor: Kristina McAteer is an attending Emergency Medicine Physician at Newport and Rhode Island Hospital.

REFERENCES

1. Amdisen A. Clinical features and management of lithium poisoning. Med Toxicol Adverse Drug Exp. 1988 Jan-Dec;3(1):18-32. doi: 10.1007/BF03259929. PMID: 3285125.

2. Hedya SA, Avula A, Swoboda HD. Lithium Toxicity. [Updated 2021 Dec 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499992/

3. Foulser P, Abbasi Y, Mathilakath A, Nilforooshan R. Do not treat the numbers: lithium toxicity. BMJ Case Rep. 2017 Jun 02;2017

4. Thanacoody, R, et al. Position paper update: Whole bowel irrigation for gastrointestinal decontamination of overdose patients. Clin Toxicol. 2015; 53(1):5-12. doi: 10.3109/15563650.2014.989326.