Consciousness disturbance due to lithium carbonate intoxication developed in a patient with cancer and bipolar affective disorder: A case report and literature review.

Background: Patients with comorbid cancer and bipolar affective disorder require psychiatric symptom stabilization to continue cancer treatment, and mood stabilizers, including lithium carbonate, are often administered during cancer treatment. However, the risk of lithium carbonate-induced consciousness disturbance seems not to be well recognized among medical professionals involved in cancer treatment. Case Presentation: A woman in her 70s was diagnosed with bipolar affective disorder at approximately 28 years of age and was hospitalized twice for worsening manic depressive episodes. Lithium carbonate (600 mg/day, orally) was administered. At X-3 years, she was diagnosed with left breast cancer (cT2N2M0, Stage IIIA) and received preoperative chemotherapy (doxorubicin, cyclophosphamide, and paclitaxel) following total mastectomy and axillary lymph node dissection. At X years, she was hospitalized because of a consciousness disturbance. Brain metastasis and lithium carbonate overdose were eliminated, and renal function was normal. However, the blood lithium level was 1.74 mEq/L, and lithium carbonate intoxication due to dehydration was most suspected. Her level of consciousness improved with adequate intravenous fluid, and she recovered with no adverse effects. Conclusions: In patients with comorbid cancer and bipolar affective disorder, the stabilization of psychiatric symptoms is necessary, and lithium carbonate is an important medication. However, oncologists and liaison psychiatrists need to consider the possible risk of consciousness disturbance due to lithium carbonate intoxication.