Plasma glutathione in health and in patients with malignant disease.

The total glutathione concentration (oxidized plus reduced) of human plasma was investigated. Glutathione was found to disappear when added to plasma, the loss of reduced glutathione being much more rapid than the loss of oxidized glutathione. The glutathione content of plasma from normal humans was found to be 0.91 +/- 0.24 mumol/L (mean +/- 1 SD) when plasma extracts were prepared exactly 10 minutes after the blood had been drawn. The glutathione content of rat plasma was about 15 times as high as that of human plasma. Patients with a variety of malignant disorders were found to have markedly lowered plasma glutathione levels. This did not seem to be associated with chemotherapy or with type of neoplasm. The administration of acetaminophen to rabbits and to human volunteers did not affect plasma glutathione levels.