Thorium Dioxide as an Aid in the Differential Diagnosis of Pylephlebitis

We have employed the use of thorium dioxide intravenously since 1932. In most instances it was used to aid in determining the presence of tumor or suppuration in the liver, and in those cases which survived the original illness, we have failed to observe any permanent harmful effects of the drug. Damaging effects to the tissues of experimental animals have been reported (1, 2, 3, 4) and its use in man has been discouraged because of its prolonged retention in the reticulo-endothelial cells, its radioactivity, which might be poisonous, and because it might produce cancerous growth. Early in 1933 in a series of unpublished experiments with dogs, we found that purpura with fatal hemorrhage from the mucous membranes could be produced with a dose of 7 c.c. per kilogram. In such animals coagulation failed to occur. But these doses were relatively enormous. We have never seen hemorrhage or petechiae in humans, although such have been reported (5). Taft (G), using a Geiger counter, estimated the gamma radiation o...