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Causes of increased and decreased white blood cells
Last reviewed: 04.07.2025
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The number of leukocytes in the blood depends on the rate of cell influx from the red bone marrow and the rate of their exit into the tissues. An increase in the number of leukocytes in the peripheral blood above 10×10 9 /l is called leukocytosis, a decrease below 4×10 9 /l is called leukopenia.
An increase or decrease in the number of individual types of leukocytes in the blood can be absolute or relative, depending on the total leukocyte content - normal, increased or decreased. The absolute content of individual types of leukocytes in a unit of blood volume can be determined using the formula: A (%) × WBC (10 9 /l) / 100%, where A is the content of a certain type of leukocytes, %. For example, an increase in the percentage of lymphocytes (60%) with a decreased total number of leukocytes (2 × 10 9 /l) means relative lymphocytosis, since the absolute number of these cells (1.2 × 10 9 /l) is within the normal range (see also "Leukocyte formula").
Most often, leukocytosis develops as a result of acute infections, especially those caused by cocci (staphylococcus, streptococcus, pneumococcus, gonococcus), E. coli, diphtheria bacillus, etc. In these infections, the number of leukocytes is usually 15-25×10 9 /l. Severe leukocytosis of 20-40×10 9 /l is typical for patients with pneumococcal pneumonia, scarlet fever, and severe burns.
Leukocytosis develops within 1-2 hours after the onset of acute bleeding, it is especially pronounced with hemorrhage into the abdominal cavity, pleural space, joint, or in close proximity to the dura mater. With the termination of a tubal pregnancy, the number of leukocytes can increase to 22×10 9 /l, after a rupture of the spleen - up to 31×10 9 /l. Leukocytosis usually accompanies an acute attack of gout (up to 31×10 9 /l).
Most patients with acute appendicitis already at the very beginning of the disease have an increase in the number of leukocytes in the blood. In the catarrhal form of appendicitis, the content of leukocytes in the blood is within 10-12×10 9 /l, changes in the leukocyte formula of the blood are usually not observed. In phlegmonous appendicitis, the number of leukocytes in the blood reaches 12-20×10 9 /l, a regenerative shift of neutrophils with a high content of band forms (up to 15%) is observed. In the gangrenous form of appendicitis, the number of leukocytes is significantly reduced (up to 10-12×10 9 /l) or is within the normal range - 6-8×10 9 /l, but the inflammatory shift in the leukocyte formula of the blood can reach a significant degree [the content of band neutrophils is 15-20% or more, the appearance of young neutrophils (4-6%) and even myelocytes (2%) is possible].
When evaluating the results of a blood test for suspected acute appendicitis, it is necessary to adhere to the conclusions made by G. Mondr (1996).
- In cases without suppuration, leukocytosis does not exceed 15×10 9 /l.
- If leukocytosis does not stop increasing during the first 6-12 hours after an acute attack (blood tests are performed every 2 hours), one should be wary of a rapidly spreading severe infectious process.
- Even if the general symptoms of the disease (pain, fever, etc.) seem to decrease, while leukocytosis continues to increase, the latter is of greater importance, since fluctuations in the severity of leukocytosis are at least 24 hours ahead of fluctuations in body temperature.
- In exceptional cases, leukocytosis may be absent; the latter is observed in cases of sudden severe intoxication of the body or when the patient is severely exhausted by a long-term infection, or when the latter is localized and the abscess encapsulates and spontaneously sterilizes.
A false increase in the white blood cell count, as calculated by an automated analyzer, may be due to cryoglobulinemia, platelet clots or aggregation, or the presence of nucleated forms of red blood cells (erythroblasts) or unlysed red blood cells, which will be counted as white blood cells.
A number of acute infections (typhoid, paratyphoid, salmonellosis, etc.) can in some cases lead to leukopenia. This is especially typical for the depletion of bone marrow reserves of neutrophils as a result of the use of modern chemotherapeutic agents, with nutritional deficiency or general weakening of the body. Some bacteria and certain viruses (yellow fever, measles, rubella, chickenpox, etc.), rickettsia and protozoa can cause leukopenia in previously completely healthy people.
Diseases and conditions accompanied by changes in the number of leukocytes
Leukocytosis |
Leukopenia |
Infections (bacterial, fungal, viral, etc.) Inflammatory conditions Malignant neoplasms Injuries Leukemia Uremia The result of the action of adrenaline and steroid hormones |
Aplasia and hypoplasia of red bone marrow Damage to bone marrow by chemicals, drugs Ionizing radiation Hypersplenism (primary, secondary) Acute leukemia Myelofibrosis Myelodysplastic syndromes Plasmacytoma Metastases of neoplasms to bone marrow Addison-Biermer disease Sepsis Typhus and paratyphus Anaphylactic shock Collagenoses Medicines (sulfonamides and some antibiotics, non-steroidal anti-inflammatory drugs, antithyroid drugs, antiepileptic drugs, etc.) |