A rare case of steroid-resistant nephrotic syndrome complicated by Wernicke's encephalopathy.

Wernicke's encephalopathy (WE) is a severe neurological condition caused by the deficiency of thiamine, which is a vitamin B1 molecule. Herein, we present the case of a 3-year-old girl with steroid-resistant nephrotic syndrome (SRNS) who did not achieve remission despite steroid pulse therapy (MPT) and rituximab. She had frequent vomiting and decreased oral intake on the 61st day. High-calorie total parenteral nutrition was initiated on the 86th day, and levothyroxine was administered for suspected hypothyroidism. On the 88th day, she experienced altered consciousness with ocular deviation and abnormal electroencephalography findings, raising suspicion of WE. Following thiamine supplementation, recurrence of symptoms and neurological sequelae were not observed. Following 10 courses of MPT, rituximab, and mycophenolate mofetil, the patient achieved incomplete remission from SRNS. Monitoring levels of water-soluble vitamins in prolonged cases of nephrotic syndrome, such as SRNS, is critical to prevent WE and irreversible neurological damage.