Objectives The symptoms of thiamine deficiency vary considerably and asymptomatic cases; i.e., subclinical thiamine deficiency (SCTD), are known to exist. However, there is no information available on the treatment of SCTD. Methods We report a patient who underwent intravenous thiamine replacement therapy for about a month after being diagnosed with SCTD, but who developed SCTD again about three weeks after finishing the treatment. Results The patient was a 64-year-old woman who, after starting treatment for cervical cancer, complained of anxiety and underwent an initial psychiatric examination. The psychiatric diagnosis was an adjustment disorder. Based on the possibility of SCTD complications due to her decreased appetite and weight loss, her serum thiamine concentration was measured and found to be low. Therefore, thiamine was administered intravenously for 29 days. At the end of treatment, thiamine administration was discontinued as there were no apparent neuropsychiatric symptoms or problems with appetite. Twenty-three days later, there were still no problems with appetite or neuropsychiatric symptoms, but a follow-up blood sample revealed that her serum thiamine was again below the normal range. Significance of results Currently, there is no information available regarding the diagnosis and treatment of SCTD in cancer patients. In some cases, such as this case, the deficiency recurs without any symptoms indicative of SCTD; therefore, further examination for diagnosis and treatment is necessary.

Objective Cancer patients often want to spend their final days at home, and it is essential that general practitioners have knowledge of and technical skills related to cancer medicine and symptom relief. Recent clinical studies have revealed that Wernicke encephalopathy (WE) is quite common in cancer patients. However, there have been no reports to date on WE in cancer patients undergoing home medical care. Methods From a series of cancer patient undergoing home medical care, we reported a patient with lung cancer who developed WE. Results An 84-year-old female with lung cancer undergoing home medical care developed an impaired mental state and an attention deficit. Her symptoms fulfilled the diagnostic criteria for delirium. WE was suspected as the patient's food intake had fallen from normal a month previously to somewhere between 50% or just a few mouthfuls. This diagnosis was supported by abnormal serum thiamine and the disappearance of delirium after thiamine administration. Significance of the results When delirium occurs in cancer patients undergoing home treatment, it is necessary to suspect thiamine deficiency as a potential cause, as appropriate diagnosis and treatment can prevent irreversible brain-related sequelae.

Background: We report a case in which a family member caring for her mother with dementia developed Wernicke encephalopathy, which is a neuropsychiatric disorder caused by acute/subacute thiamine deficiency, during the course of care. Case presentation: A 63-year-old woman consulted our psychiatric outpatient clinic complaining of difficulty in providing care. She had started caring for her mother with dementia 6 months previously, during which time she began to feel tired. In addition, a loss of appetite had appeared 2 months prior to her visit, and this had decreased to about 30% of normal from 10 days previously. Neurologically, she experienced mild unsteadiness, but she was fully conscious and had no ocular symptoms. Based on the fact that the store of thiamine in the body is exhausted in about 18 days, the possibility of thiamine deficiency was considered, and her unsteadiness disappeared after an intravenous injection of thiamine. Test results showed her serum thiamine level to be abnormally low, and the patient was diagnosed with Wernicke encephalopathy. Conclusions: The burden of caring for a dementia patient may affect the nutritional status of the family caregiver. Thiamine deficiency should be one of the items considered as a nutritional issue in such caregivers.