Q&A: Concerning Neutrophilia and Left Shift

Neutrophilia refers to an increase of peripheral blood neutrophils at least two standard deviations above the mean. For adults, this generally corresponds to >7700 neutrophils/microL (typically seen in patients with >11,000 white blood cells/microL).

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In this article:
Normal white blood cell (WBC) range
MCQ: clinical scenario
MCQ: answer
MCQ: explanation

Normal white blood cell (WBC) range

The normal range (ie, two standard deviations above and below the mean) for the white blood cell (WBC) count in adults is 4400 to 11,000 cells/microL in most clinical laboratories. Approximately 60 to 70 percent of leukocytes in the peripheral blood are mature polymorphonuclear neutrophils (PMN). Thus, the threshold for neutrophilia in most clinical laboratories is approximately 7700/microL (11,000 WBC/microL x 70 percent).

Normal values for WBC in children vary based on age.

MCQ: clinical scenario

A 13 year old female has swollen cervical lymph nodes and is febrile. Her blood culture is positive for staphylococcus aureus. She shows other signs of being septic. The intern attending her tells her associate that the patient's WBC count is 15,000 cc/mm with a shift to the left.

What does she mean by a 'shift to the left?'

a) increased number of white blood cells in the peripheral blood
b) decreased number of white blood cells in the peripheral blood
c) hypersegmented granulocytes present in the peripheral blood
d) increased number of immature white blood cells in the peripheral blood
e) increased number of immature red blood cells in the peripheral blood

MCQ: answer

The correct answer is D

MCQ: explanation

A shift to the left refers to an increase number of immature white blood cells in the peripheral smear. Typically, the immature white blood cells are being released prematurely by the bone marrow in order to combat some sort of infection. An increased number of white blood cells in the peripheral blood (choice a) is called a leukocytosis. A decreased number of white blood cells in the peripheral blood (choice b) is called a leukopenia. Hypersegmented granulocytes present in the peripheral blood (choice c) is a shift to the right. An increased number of immature red blood cells in the peripheral blood (choice e) is a reticulocytosis.

Useful definitions include:

• Absolute neutrophil count (ANC) = WBC (cells/microL) x percent (PMNs + bands) ÷ 100 
• Neutrophilia typically corresponds to ANC >7700/microL
• Leukocyte refers to any type of WBC, including neutrophils, eosinophils, basophils, monocytes, and lymphocytes.
• Leukocytosis refers to elevated WBC (leukocyte) count. Neutrophilia is the most common type of leukocytosis, but leukocytosis may also be due to increased monocytes, eosinophils, basophils, and/or lymphocytes.
• Granulocytosis is often used interchangeably with neutrophilia, but granulocytosis is a broader term that can also reflect increased eosinophils or basophils.
• Left shift is an ill-defined term that refers to an increase in the percentage of band forms, generally accompanied by metamyelocytes and myelocytes.
• Leukemoid reaction refers to WBC >50,000/microL from causes other than leukemia, with the majority being mature neutrophils, often accompanied by increased numbers of bands, metamyelocytes, and/or myelocytes. 

Reference(s)
1). UpToDate: Approach to the patient with neutrophilia. Available online: https://www.uptodate.com/contents/approach-to-the-patient-with-neutrophilia