NEPHROGENIC DIABETES-INSIPIDUS PRESENTING AFTER HEAD TRAUMA

Water diuresis after head trauma is most often due to central diabetes insipidus (DI). We report a patient with a history of a bipolar disor der and past lithium use who was noted to have polyuria and hypernatre mia after head trauma. Inappropriate high sodium and volume replacemen t resulted in an increase in the polyuria. A lack of response to antid iuretic hormone/antidiuretic-hormone-like preparations led to the diag nosis of nephrogenic DI. The case illustrates the importance of calcul ating electrolyte-free osmolar clearance in the correction of hypernat remia. Persistence of the DI and mild renal impairment probably due to past lithium use are discussed.