ABSTRACT
Meningitis and other infectious diseases of the central nervous system are predisposing causes of the inadequate secretion syndrome of the antidiuretic hormone (ISADH). The association between the acquired immunodeficiency syndrome (AIDS) and ISADH is recognized but little studied. In AIDS patients hyponatremia is a frequent finding and it is responsible for ISADH in most cases. However, there is little reference material concerning the incidence of presentation and the type of osmoregulation anomaly this entity presents in these patients. A case in which ISADH is associated to cryptococcal meningitis and AIDS is described with an evaluation of the hormonal response to the test of hypertonic saline serum infusion corresponding to a release of ADH.