Case presentation
A 61-year-old Japanese woman was referred to our psychiatric ward due to disturbance of consciousness. She had been diagnosed with schizoaffective disorder at 17 years of age and had been subsequently treated with several antipsychotic drugs, including lithium. Psychiatric symptoms were predominantly negative, and included decreased motivation, emotional flatness, and autism. She visited an outpatient clinic regularly for a long period of time; her last measurement of lithium concentration in serum was 0.51 mmol/L. She had been diagnosed with stage IIIC1 endometrial cancer with lymph node metastases (T2N1M0) at 59 years of age. She underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node dissection accompanied by adjuvant pelvic radiotherapy. Within the same year, multiple distant metastases were found, and the patient received chemotherapy consisting of six cycles of docetaxel/carboplatin. Three months after the end of chemotherapy, the cancer recurred in the liver and para-aortic lymph nodes. The patient received six cycles of doxorubicin/cisplatin together with radiotherapy for the metastatic para-aortic lymph node. However, tumor progression could not be controlled, the patient developed ascites and hydronephrosis, and renal function decreased. Although her serum creatinine level was approximately 2.0 mg/dl, she refused the insertion of a ureteral stent. She gradually became unable to walk and suffered from appetite loss. She received palliative care, as her survival time was estimated to be only of several months. Fortunately, she did not suffer from severe cancer pain and did not need to be treated with any non-steroidal anti-inflammatory drugs or opioids. Her physical functions had deteriorated during this period; she developed a gait disturbance and could not maintain a seated position. Subsequently, she became confused. Her consciousness was cloudy and accompanied by dysarthria and myoclonus. At this point the patient was admitted to the Obstetrics and Gynecology ward of our university hospital. She had hypotension, tachycardia, and a mild fever. The patient’s laboratory data are presented in Table 1 . Electrocardiography and head computed tomography revealed no abnormalities. The focus of the infection could not be determined from blood or urine samples, or from a computed tomography scan, and an enhanced inflammatory response due to tumor progression was considered as a possible diagnosis. The reason for the decreased renal function was determined to be the extreme dehydration derived from cancer cachexia. She was referred to the outpatient department of our hospital because of delirium associated to her deteriorating general condition. Her total score on the delirium rating scale-revised-98 (DRS-R-98) 8 was 23 points. Thus, we diagnosed the patient with delirium associated with progressive-stage cancer. Given that she was being treated with several psychotropic drugs (i.e., lithium 300 mg/day, haloperidol 2.25 mg/day, chlorpromazine 25 mg/day, biperiden 6 mg/day, flunitrazepam 2 mg/day, and suvorexant 20 mg/day) and she demonstrated reduced renal function as assessed by the serum creatinine test, her levels of lithium in serum were checked and found to have a value considered toxic (3.02 mEq/L). The patient received hemodialysis immediately; her serum lithium concentration decreased to 1.68 mEq/lL after the first session and finally to 0.98 mEq/L after the second session. The clouded consciousness, dysarthria, and myoclonus recovered and eventually disappeared in parallel to the decrease in the serum lithium levels (her DRS-R-98 score decreased to 4 points). Moreover, the gait disturbance and postural retention disorder were completely resolved. Results from the blood tests after the treatment are shown inTable 1. There was no further worsening of mental status after lithium treatment was discontinued.