A 31-year-old woman is brought to the emergency department by her boyfriend due to confusion. The boyfriend says that the patient "seemed okay" when he left for work this morning, but when he returned in the evening, she was disoriented and "acting like a drunk person"; she had also vomited "all over the bathroom." The patient was recently fired due to interpersonal problems with other employees. She has a history of bipolar disorder. Medications include clonazepam, lithium, and quetiapine. Temperature is 37 C (98.6 F), blood pressure is 110/68 mm Hg, pulse is 92/min, and respirations are 16/min. On physical examination, the patient is somnolent and has frequent fasciculations. Pupils are equal and reactive. During evaluation, she has a brief episode of a generalized tonic-clonic seizure. Laboratory results are as follows: Acetaminophen and salicylate are not detected in the serum, and urine drug screen is negative. A noncontrast CT scan of the head shows no abnormalities. In addition to supportive measures, which of the following is the best next step in management of this patient?

Question

A 31-year-old woman is brought to the emergency department by her boyfriend due to confusion.  The boyfriend says that the patient "seemed okay" when he left for work this morning, but when he returned in the evening, she was disoriented and "acting like a drunk person"; she had also vomited "all over the bathroom."  The patient was recently fired due to interpersonal problems with other employees.  She has a history of bipolar disorder.  Medications include clonazepam, lithium, and quetiapine.  Temperature is 37 C (98.6 F), blood pressure is 110/68 mm Hg, pulse is 92/min, and respirations are 16/min.  On physical examination, the patient is somnolent and has frequent fasciculations.  Pupils are equal and reactive.  During evaluation, she has a brief episode of a generalized tonic-clonic seizure.  Laboratory results are as follows:  Acetaminophen and salicylate are not detected in the serum, and urine drug screen is negative.  A noncontrast CT scan of the head shows no abnormalities.  In addition to supportive measures, which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient is experiencing acute lithium toxicity. Neurologic (eg, altered mental status, seizure, fasciculations, tremor) and gastrointestinal (eg, vomiting, diarrhea) signs are common in cases of acute intoxication. Although mild overdoses can frequently be managed supportively with hydration and monitoring, hemodialysis is the treatment of choice for patients with lithium levels >2.5 mEq/L and prominent signs of toxicity. Patients with levels >4 mEq/L and creatinine >2.0 mg/dL should generally be prescribed dialysis regardless of symptoms. Because lithium is renally excreted, common precipitants of toxicity include medications that affect the excretion rate (eg, nonsteroidal anti-inflammatory drugs, ACE inhibitors, angiotensin receptor blockers) as well as dehydration by any cause (eg, diuretics, gastrointestinal illness). Intentional overdose should also always be on the differential. (Choices A and D) Activated charcoal does not absorb cations such as lithium, and gastric lavage is ineffective for lithium toxicity. (Choices B and F) Calcium gluconate may be used in cases of hypocalcemia and hyperkalemia. Magnesium sulfate is used in the treatment of hypomagnesemia, torsade de pointes, and preeclampsia. They have no indication for use in lithium toxicity. (Choice C) Flumazenil, a selective GABA-A antagonist, is an antidotal therapy for benzodiazepine overdose but is rarely used because of the risk of seizures. Manifestations of benzodiazepine overdose include slurred speech, ataxia, and depressed mental status with normal vital signs; fasciculations and gastrointestinal symptoms would be uncommon. (Choice G) Physostigmine is an acetylcholinesterase inhibitor used as antidotal therapy for anticholinergic poisoning. Anticholinergic poisoning can cause confusion (eg, mad as a hatter) but would also cause vasodilation (eg, red as a beet), anhidrosis (eg, dry as a bone), nonreactive mydriasis (eg, blind as a bat), and hallucinations (eg, mad as a hatter) with tachycardia and absent/decreased bowel sounds. Educational objective: Lithium toxicity presents with neurologic (eg, altered mental status, seizure, fasciculations, tremor) and gastrointestinal (eg, vomiting, diarrhea) signs. The treatment of choice is hemodialysis. References: Extracorporeal treatment for lithium poisoning: systematic review and recommendations from the EXTRIP Workgroup. (http://www.ncbi.nlm.nih.gov/pubmed/25583292) Lithium poisoning. (http://www.ncbi.nlm.nih.gov/pubmed/27516079)

A 31-Year-Old Woman Is Brought to the Emergency Department by Her