What is LR?

A leukemoid reaction (LR) is a hematological disorder, defined by a leukocyte count greater than 50,000 cells/mcL with reactive causes outside the bone marrow

LR is characterized by a significant increase in mature neutrophils in the peripheral blood and a differential count showing left shift.

The diagnosis of LR is based on the exclusion of chronic myelogenous leukemia (CML) and chronic neutrophilic leukemia (CNL).