Lactic dehydrogenase (LDH) of mouse serum has been determined in animals with induced and transplanted tumors as well as in pregnant ones. It was found that only with malignant tumors, whether transplanted or induced, did serum LDH increase. Mice with papillomas or in stages of epidermal hyperplasia resulting from the application of methylcholanthrene gave normal serum LDH values. Pregnancy seemed to have no significant effect on serum LDH.
Aided by grants from the Charles F. Kettering Foundation and the American Cancer Society.