Renal and extrarenal considerations in high-dose mannitol therapy.

It is well recognized that the large doses of mannitol used in treating cerebral edema alter extracellular fluid (ECF) volume, osmolality, and composition to a degree which, under some circumstances, can lead to acute renal failure, cardiac decompensation, and other difficulties. It is less well appreciated that the patient's body habitus, age, total body water content relative to body weight, pretreatment plasma sodium concentration and plasma osmolality, and the presence of edema or ascites also can influence the degree of ECF change and the rate of mannitol excretion to a significant degree. Here, we show how these changes occur and the way in which their magnitude can be predicted prior to therapy so as to minimize the risk of an adverse result.