Intranasal desmopressin-induced hyponatremia

Desmopressin is a commonly used, well-tolerated agent for the treatment of primary nocturnal enuresis and central diabetes insipidus. Intranasal desmopressin provides symptomatic relief with few serious complications. A 29-year-old woman with a long history of primary nocturnal enuresis began treatment with intranasal desmopressin. Although the enuresis ceased, she developed throbbing headaches, nausea, vomiting, paresthesia, lethargy, fatigue, and altered mental status over the next 7 days. When she came to the emergency room her sodium concentration was 127 mmol/L. The history of desmopressin use was not obtained at that time. She was treated with intravenous fluids and discharged. The symptoms returned and worsened over the next 4 days, and she returned to the emergency room stuporous. A repeat sodium was 124 mmol/L, and she was admitted. The history of desmopressin use was still not available. Medical evaluations included computerized tomography, lumbar puncture, complete blood counts, serum chemistries, and serologies. The next morning the woman was improved and informed clinicians of her desmopressin use. Without other causes for the hyponatremia, she was diagnosed with the syndrome of inappropriate antidiuretic hormone, presumably caused by desmopressin. Within 24 hours of fluid restriction and cessation of desmopressin, her symptoms and hyponatremia resolved. A review of the literature found 11 children and 2 adults in whom intranasal desmopressin was associated with hyponatremia, all of whom experienced seizures or altered mental status. Our patient illustrates the importance of early recognition and treatment of hyponatremia before the onset of seizures. When vague symptoms develop during desmopressin therapy, hyponatremia must be considered as part of the differential diagnosis. It may also be prudent to screen for electrolyte abnormalities in patients taking this agent to prevent serious iatrogenic complications.