Water intoxication induced by low-dose oral cyclophosphamide in a patient with anti-neutrophil cytoplasmic antibody-related glomerulonephritis

We reported the case of a 70-year-old woman with moderate renal failure due to anti-neutrophil cytoplasmic antibody-related glomerulonephritis who developed symptomatic water intoxication (serum Na: 108 mEq/L) following treatment with oral low-dose cyclophosphamide (CY) (50mg/day). Estimated glomerular filtration rate was 29.5 mL/min/1.73 m(2). She had drunk >2 L of fluid in 12 h prior to the development of cerebral oedema. This rare case suggests that oral low-dose CY could be an occult cause of water intoxication in patients with chronic kidney disease taking large fluid volumes.