title: Water intoxication induced by low-dose cyclophosphamide in two patients with systemic lupus erythematosus.
abstract: Cyclophosphamide (CY) is an alkylating agent used to treat a variety of autoimmune disorders. Water intoxication is a well-known complication of high-dose intravenous (i.v.) CY, but is rare in patients treated with low dose i.v. CY. We describe two patients with lupus nephritis and water intoxication following low dose i.v. CY. The first patient was treated with oral prednisolone and azathioprine for eight weeks with inadequate response and persistent renal inflammatory activity. Eight hours after the first i.v. CY pulse she had a grand mal seizure. The second patient had WHO class III lupus nephritis, and after a single i.v. CY pulse developed vomiting, diarrhoea and grand mal seizures. They were both fluid-restricted and their serum sodium levels returned to normal. In conclusion, even at low doses i.v. CY may induce hyponatremia related to inappropriate antidiuretic hormone secretion. This potentially life-threatening complication of i.v. CY could be minimized by avoidance of overhydration following pulse i.v. CY.
authors.affiliation: Lupus Research Unit, Rayne Institute, St Thomas' Hospital, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Salido
authors.forename: P
authors.initials: P
authors.lastname: Macarron
authors.forename: C
authors.initials: C
authors.lastname: Hernández-García
authors.forename: D P
authors.initials: DP
authors.lastname: D'Cruz
authors.forename: M A
authors.initials: MA
authors.lastname: Khamashta
authors.forename: G R V
authors.initials: GR
authors.lastname: Hughes
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage / Q000009:adverse effects*; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000009:adverse effects*; D007275:Injections, Intravenous; D008180:Lupus Erythematosus, Systemic / Q000188:drug therapy*; D008181:Lupus Nephritis / Q000139:chemically induced; D008875:Middle Aged; D014869:Water Intoxication / Q000139:chemically induced*
chemical_list: D018906:Antineoplastic Agents, Alkylating; D007166:Immunosuppressive Agents; D003520:Cyclophosphamide