Summary
Left shift or blood shift is an increase in the number of immature cell types among the blood cells in a sample of blood. Many (perhaps most) clinical mentions of left shift refer to the white blood cell lineage, particularly neutrophil-precursor band cells,[1]: 84–84 thus signifying bandemia. Less commonly, left shift may also refer to a similar phenomenon in the red blood cell lineage in severe anemia, when increased reticulocytes and immature erythrocyte-precursor cells appear in the peripheral circulation.[2]
Definition edit
The standard definition of a left shift is an absolute band form count greater than 7700/microL.[3] There are competing explanations for the origin of the phrase "left shift," including the left-most button arrangement of early cell sorting machines[4][5] and a 1920s publication by Josef Arneth, containing a graph in which immature neutrophils, with fewer segments, shifted the median left.[6] In the latter view, the name reflects a curve's preponderance shifting to the left on a graph of hematopoietic cellular differentiations.
Morphology edit
It is usually noted on microscopic examination of a blood smear. This systemic effect of inflammation is most often seen in the course of an active infection and during other severe illnesses such as hypoxia and shock. Döhle bodies may also be present in the neutrophil's cytoplasm in the setting of sepsis or severe inflammatory responses.[1]: 663–664
Pathogenesis edit
It is believed that cytokines (including IL-1 and TNF) accelerate the release of cells from the postmitotic reserve pool in the bone marrow, leading to an increased number of immature cells.[1]: 84–84
See also edit
References edit
- ^ a b c Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Robbins, Stanley Leonard; Cotran, Ramzi S. (30 July 2004). Robbins & Cotran Pathologic Basis of Disease (7th ed.). Philadelphia, PA: Saunders. ISBN 9780721601878. LCCN 2004046835. OCLC 249701397. OL 7862642M.
- ^ Rodak, Bernadette F.; Fritsma, George A.; Doig, Kathryn (2007). Hematology: clinical principles and applications (3rd ed.). Elsevier Health Sciences. p. 171. ISBN 978-1-4160-3006-5.
- ^ Coates, Thomas D (December 22, 2008), "Approach to the patient with neutrophilia", UpToDate Online, 17.3, Wolters Kluwer, retrieved December 21, 2009
- ^ Reed, Larry (26 October 2010). "The Meaning of a Shift to the Left". Medicine out of the box. Archived from the original on 24 July 2021. Retrieved 5 August 2022.
- ^ Krafts, Kristine (4 April 2009). "Left shift". Pathology Student. Archived from the original on 14 December 2021. Retrieved 5 August 2022.
The term "left shift" almost always refers to the neutrophil series. It arose during the days when cells were counted by hand using a manual counting machine. The most mature cells (segmented neutrophils) were assigned to the right-most button, the least mature cells (myeloblasts) were assigned to the left-most button, and the other stages of cells were spread out in order in the buttons in between. In a normal blood smear, virtually all the neutrophils fell under the right-most counting button, but sometimes, it was noted that there were earlier precursors present (e.g., myelocytes, metamyelocytes, or promyelocytes). In these instances, the cells were "shifted" towards the left.
- ^ Rodak, B.F.; Fritsma, G.A.; Keohane, E. (2012). Hematology: Clinical Principles and Applications, 4th Ed. Saunders. p. 205. ISBN 978-1437706925. Retrieved 14 Apr 2015.