Serum Enzymes in Bronchogenic Carcinoma and Other Pulmonary Diseases

1. Serial serum lactic dehydrogenase (LDH) determinations revealed increased activity in 82 per cent of patients with histologically proved bronchogenic carcinoma. 2. Serum lactic dehydrogenase activity was elevated in 71 per cent of patients with acute pneumonia, but interval studies noted a return to normal levels in all cases as the pneumonic process subsided. 3. Tuberculosis did not affect the blood levels of lactic dehydrogenase. 4. The serum lactic dehydrogenase frequently returned to normal following surgery, x-ray, or chemotherapy for bronchogenic carcinoma. Post therapy serum LDH studies appeared to be of prognostic value. 5. The serum transaminase was found to be of no particular value in the diagnosis of bronchogenic carcinoma.