An update on the etiology and diagnostic evaluation of a leukemoid reaction

Eur J Intern Med. 2006 Oct;17(6):394-8. doi: 10.1016/j.ejim.2006.04.004.


Persistent neutrophilic leukocytosis above 50,000 cells/muL when the cause is other than leukemia defines a leukemoid reaction. The diagnostic work-up consists of the exclusion of chronic myelogenous leukemia (CML) and chronic neutrophilic leukemia (CNL) and the detection of an underlying cause. The major causes of leukemoid reactions are severe infections, intoxications, malignancies, severe hemorrhage, or acute hemolysis. The present article points out the difficulties in the differential diagnosis of a leukemoid reaction and suggests an algorithm for a rational clinical and laboratory evaluation of this problematic entity.