[Recurrent hyponatremia, neurological symptoms and long-term administration of levomepromazine]

We present the case of an 84 year old lady with an episode of marked hyponatremia with acute neurological disturbances which in the latest case resolved completely after a 3 day period of fluid restriction. The more common causes of hyponatremia could be ruled out. There was no evidence for a neuroleptic drug associated change in serum sodium concentration. We conclude that the patient in this study belongs to a subset of geriatric patients in whom there is an intermittent SIADH which only becomes clinically evident when several factors coincide. The underlying mechanisms are not understood but could include the interaction of subclinical cerebrovascular disease and treatment with a neuroleptic drug in an elderly patient whose water and sodium homeostasis is compromised by the changes of normal aging which affect the many systems involved in maintaining water and sodium balance.