Effect of dimethyl sulfoxide on serum osmolality.

Consecutive values for serum osmolality measured in a patient exceeded (548 mOsm) the previously reported pathological range and, indeed, exceeded that generally considered compatible with life. The patient was receiving large amounts of intravenous dimethyl sulfoxide as part of an experimental protocol to control intracranial pressure resulting from trauma. This compound increases serum osmolality linearly with respect to concentration over the range considered therapeutically significant, 0 to 10 mL/L. The mechanism of its effect on osmolality readings is discussed. It does not interfere with any values for those routine measurements made by continuous-flow (SMAC, Technicon).