Cyclophosphamide induced water intoxication in a woman with Sjögren's syndrome

Water intoxication is a well described complication of high dose intravenous (i.v.) cyclophosphamide therapy combined with forced hydration. Less well known is that water intoxication can develop even after low dose iv cyclophosphamide. To draw attention to this potentially life threatening complication, we describe a woman who developed acute water intoxication after treatment with low dose iv cyclophosphamide for a sensory neuropathy secondary to Sjögren's syndrome. Rheumatologists should be aware of this serious adverse effect of iv cyclophosphamide because this drug is being used increasingly for treatment of a variety of rheumatological diseases. The pathogenesis, clinical characteristics, treatment, and methods for prevention of cyclophosphamide induced water intoxication are discussed.