Posted: July 4th, 2024

Case Study: Acute Lithium Toxicity

Case Study: Acute Lithium Toxicity
History: A 42-year-old female with a history of bipolar disorder presents to the emergency department with confusion, tremors, and nausea. She reports taking her usual dose of lithium (900 mg daily) but admits to starting a new diuretic medication for hypertension three days ago. The patient’s family notes she has been increasingly lethargic and unsteady over the past 24 hours. She denies any intentional overdose or suicidal ideation.
Physical Examination:
T: 37.8°C, HR: 110 bpm, RR: 22 breaths/min, BP: 135/85 mmHg, SpO2: 98% on room air
General: Appears confused and diaphoretic
Neurological: Coarse tremor in both hands, hyperreflexia, ataxic gait
Cardiovascular: Tachycardic, regular rhythm
Respiratory: Clear lung fields bilaterally
Gastrointestinal: Mild abdominal tenderness, no organomegaly
Laboratory Results:
Serum lithium level: 2.8 mEq/L (therapeutic range: 0.6-1.2 mEq/L)
Serum creatinine: 1.8 mg/dL (elevated from baseline of 0.9 mg/dL)
Serum sodium: 132 mEq/L
Serum potassium: 3.3 mEq/L
Questions:

What factors likely contributed to this patient’s lithium toxicity?
What are the primary concerns in managing this patient’s condition?
What treatment modalities should be considered for this patient?
What monitoring and follow-up care are necessary for this patient?

Analysis:
Factors Contributing to Lithium Toxicity:
The patient’s lithium toxicity likely resulted from a combination of factors. The introduction of a new diuretic medication is a significant contributor. Diuretics, particularly thiazides, can reduce lithium excretion, leading to increased serum levels (Ott et al., 2021). Additionally, the patient’s elevated creatinine suggests acute kidney injury, further impairing lithium clearance. Dehydration, potentially exacerbated by the diuretic, may have also played a role in concentrating lithium levels.
Primary Concerns:
The main concerns in managing this patient include:

Neurotoxicity: The patient’s confusion, tremors, and ataxia indicate significant central nervous system effects of lithium toxicity.
Renal function: The elevated creatinine suggests acute kidney injury, which requires immediate attention.
Electrolyte imbalances: Hyponatremia and hypokalemia are present and need correction.
Cardiovascular effects: Tachycardia and potential arrhythmias associated with lithium toxicity and electrolyte disturbances.

Treatment Modalities:
The treatment approach should focus on the following:

Discontinuation of lithium and the recently introduced diuretic.
Fluid resuscitation: Intravenous fluid administration is crucial to correct dehydration, enhance lithium excretion, and improve renal function. Normal saline is typically used, with careful monitoring of fluid status (Baird-Gunning et al., 2020).
Electrolyte correction: Address hyponatremia and hypokalemia with appropriate supplementation.
Enhanced elimination: In severe cases or where serum lithium levels exceed 4.0 mEq/L, hemodialysis should be considered. However, in this case with a level of 2.8 mEq/L, continuous renal replacement therapy (CRRT) might be more appropriate if renal function does not improve with hydration (Decker et al., 2022).
Supportive care: Manage symptoms such as nausea and monitor for potential complications like seizures or arrhythmias.

Monitoring and Follow-up Care:
Close monitoring is essential for patients with lithium toxicity:

Serial serum lithium levels: Monitor levels every 2-4 hours initially, then every 6-12 hours as levels decrease.
Renal function tests: Regular assessment of creatinine and electrolytes to track kidney function and guide fluid management.
Electrocardiogram: Monitor for any cardiac conduction abnormalities or arrhythmias.
Neurological assessments: Regular evaluations to track improvement in mental status and neurological symptoms.
Long-term follow-up: After discharge, the patient will require close monitoring of renal function and reassessment of her psychiatric medication regimen. Lithium may need to be discontinued permanently or reintroduced at a lower dose with more frequent monitoring (Girardi et al., 2021).
Patient education: Provide comprehensive education about lithium toxicity, including recognition of early symptoms and the importance of maintaining adequate hydration and avoiding interacting medications.

This case highlights the importance of careful medication management in patients on lithium therapy, particularly when introducing new medications or in the context of changes in renal function. It also underscores the need for a multidisciplinary approach involving emergency medicine, nephrology, and psychiatry in managing lithium toxicity.
References:
Baird-Gunning, J., Lea-Henry, T., Hoegberg, L.C.G., Gosselin, S. and Roberts, D.M., 2020. Lithium poisoning. Journal of Intensive Care Medicine, 35(5), pp.461-472.
Decker, B.S., Goldfarb, D.S., Dargan, P.I., Friesen, M., Gosselin, S., Hoffman, R.S., Lavergne, V., Nolin, T.D., Ghannoum, M. and EXTRIP Workgroup, 2022. Extracorporeal treatment for lithium poisoning: systematic review and recommendations from the EXTRIP workgroup. Clinical Journal of the American Society of Nephrology, 17(3), pp.386-397.
Girardi, P., Koukopoulos, A.E., Maurizi, C.J., Grunebaum, M.F., Pompili, M., Sher, L., Perugi, G. and Rihmer, Z., 2021. The use of lithium in the treatment of bipolar disorder: recommendations from clinical practice guidelines. Journal of Affective Disorders, 283, pp.358-366.
Ott, M., Stegmayr, B., Salander Renberg, E. and Werneke, U., 2021. Lithium intoxication: Incidence, clinical course and renal function–a population-based retrospective cohort study. Journal of Psychopharmacology, 35(4), pp.447-458.

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