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Causes of a shift in the white blood cell count
Last reviewed: 06.07.2025
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Diseases and conditions accompanied by a shift in the leukocyte formula
Left shift (meta-myelocytes and myelocytes are present in the blood) |
Left shift with rejuvenation (metamyelocytes, myelocytes, promyelocytes, myeloblasts and erythroblasts are present in the blood) |
Right shift (decrease in the number of band neutrophils in combination with the presence of hypersegmented neutrophil nuclei) |
Acute inflammatory processes Purulent infections Intoxications Acute bleeding Acidosis and comatose states Physical overexertion |
Chronic leukemia Erythroleukemia Myelofibrosis Metastases of neoplasms Acute leukemia Coma states |
Megaloblastic anemia Kidney and liver diseases Conditions after blood transfusion |
In many severe infections, septic and purulent processes, the leukocyte formula changes due to an increase in the number of band neutrophils, metamyelocytes and myelocytes. Such a change in the leukogram with an increase in the percentage of young forms of neutrophils is called a left shift; an increase mainly due to segmented and polysegmented forms is a right shift. The severity of the shift in neutrophil nuclei is assessed by the shift index (SI).
IS = (M + MM + P) / S,
Where M is myelocytes, MM is metamyelocytes, P is band neutrophils, S is segmented neutrophils. The reference value of SI is 0.06. The SI value is an important criterion determining the severity of the acute infection and the overall prognosis.
When analyzing the results of the white blood cell count in a blood smear, it should always be remembered that this method is not very accurate and may be a source of errors that cannot be completely eliminated (including errors in blood collection, smear preparation and staining, human subjectivity in interpreting cells). Some cell types, especially monocytes, eosinophils and basophils, are distributed in the smear in a completely irregular manner. A high content of these cells, especially in a limited area of the smear, must be rechecked before the result is given. If the number of leukocytes in the blood is more than 35×10 9 /l, it is recommended to count at least 200 cells for greater accuracy. The number of leukocytes examined should increase proportionally to the increase in leukocytosis in order to evaluate a larger area of the smear. If the number of leukocytes in the blood is less than 2×10 9 /l, some laboratories count less than 100 cells. However, this sharply reduces the accuracy, so such a count is not recommended. If it is not possible to find 100 cells in the smear, it is suggested to make a leukocyte concentrate, but it should be remembered that during the preparation of the latter, morphological changes in leukocytes and an uneven distribution of cell types occur. If less than 100 or more than 100 cells were counted, this should be reflected in the result form.
95% confidence interval for calculating the leukocyte formula in a blood smear
Content of a certain cell type,% |
Total number of cells counted |
|||
100 |
200 |
500 |
1000 |
|
0 |
0-4 |
0-2 |
0-1 |
0-1 |
1 |
0-6 |
0-4 |
0-3 |
0-2 |
2 |
0-8 |
0-6 |
0-4 |
1-4 |
3 |
0-9 |
1-7 |
1-5 |
2-5 |
4 |
1-10 |
1-8 |
2-7 |
2-6 |
5 |
1-12 |
2-10 |
3-8 |
3-7 |
6 |
2-13 |
3-11 |
4-9 |
4-8 |
7 |
2-14 |
3-12 |
4-10 |
5-9 |
8 |
3-16 |
4-13 |
5-11 |
6-10 |
9 |
4-17 |
5-14 |
6-12 |
7-11 |
10 |
4-18 |
6-16 |
7-13 |
8-13 |
15 |
8-24 |
10-21 |
11-19 |
12-18 |
20 |
12-30 |
14-27 |
16-24 |
17-23 |
25 |
16-35 |
19-32 |
21-30 |
22-28 |
30 |
21-40 |
23-37 |
26-35 |
27-33 |
35 |
25-46 |
28-43 |
30-40 |
32-39 |
40 |
30-51 |
33-48 |
35-45 |
36-44 |
45 |
35-56 |
38-53 |
40-50 |
41-49 |
50 |
39-61 |
42-58 |
45-55 |
46-54 |
The leukocyte intoxication index (LII) has become widely used to assess the severity of endogenous intoxication; the reference value for it is approximately 1.0. The calculation formula is as follows.
LII = [4(myelocytes) + 3(metamyelocytes) + 2(band neutrophils) + (segmented) × (plasma cells+1)] / [(lymphocytes+monocytes) × (eosinophils+1)]
Fluctuations in LII in patients with infectious and septic diseases objectively correspond to changes in the clinical picture and the degree of endogenous intoxication. An increase in LII to 4-9 indicates a significant bacterial component of endogenous intoxication, a moderate increase (to 2-3) indicates either a limitation of the infectious process or a focus of necrobiotic tissue changes. Leukopenia with a high LII is an alarming prognostic sign. LII can be used to assess the effectiveness of the treatment.
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