Leukocytosis in acute pulmonary embolism.

PURPOSE: The purpose of this investigation is to assess the level of leukocytosis in acute pulmonary embolism (PE). BACKGROUND: Limited data exist regarding leukocytosis in acute PE. One reason that the prevalence of leukocytosis in acute PE is unknown, despite an extensive number of investigations of PE, may relate to the fact that acute PE is usually associated with other conditions that themselves may cause leukocytosis. METHODS: Hospital records of 386 patients with a diagnosis of acute PE were reviewed retrospectively. Patients with no other possible or definite cause of leukocytosis were analyzed separately. A diagnosis of PE was made by a high-probability interpretation of the ventilation/perfusion lung scan or pulmonary angiogram. RESULTS: Among patients with PE in whom other possible or defined causes for leukocytosis were eliminated, 52 of 266 (20%) had a WBC count > 10,000/mm3. None had a WBC count that was > or = 20,000/mm3. Patients with the pulmonary hemorrhage/infarction syndrome had an increased WBC count in 32 of 183 (17%) vs 20 of 83 (24%) in patients who did not have pulmonary hemorrhage/infarction syndrome (not significant). CONCLUSION: A modest leukocytosis may accompany (and possibly be caused by) PE. Its presence should not dissuade the clinician from objectively pursuing the diagnosis of PE.