Diagnostic Sensitivity of Laboratory Findings in Acute Pulmonary Embolism

Many different laboratory tests have been used to screen patients for pulmonary embolism. The sensitivity of certain laboratory tests was assessed in a prospective study of 50 patients with angiographically documented acute pulmonary embolism. Electrocardiographic evidence of right heart strain occurred in only nine patients; each had massive pulmonary embolism. Nonspecific chest X-ray abnormalities (infiltrate, effusion, or elevated diaphragm) occurred in 71%; 29% had a normal chest X ray. Lactic dehydrogenase (LDH) was increased in 83% of the patients, but serum glutamic-oxalacetic transaminase (SGOT) and bilirubin were of little value. The triad of increased LDH, normal SGOT, and increased bilirubin occurred in only 12%. Lung scans performed in 24 patients were abnormal. Arterial Po2 (breathing room air) was decreased (≤ 80 mm Hg) in all 36 patients tested. Arterial Po2 and lung scan are the most sensitive tests for screening; if either is normal, acute pulmonary embolism is essentially excluded.