Leukocytes
Norm
Adults 4.0–10.0 ×109/l
Children
0–12 hours after birth 13.0–38.0× 109/l
1–3 days after birth 9.4–25.0 ×109/l
1 week 5.0–15.0 ×109/l
2–3 weeks 5.0–11.0 ×109/l
1 month 6.0–14.5 ×109/l
2 months 6.0–12.0 ×109/l
3–6 months 5.5–11.5 ×109/l
7–24 months 5.0–10.6 ×109/l
3–6 years 4.2–10.3 ×109/l
7–12 years 4.0–10.1 ×109/l
Synonyms: WBC, total leukocyte count, white blood cells, white blood cells.
Blood EDTA
Purple lid
An equal increase in all five leukocyte classes is called balanced leukocytosis, and a decrease is called balanced leukocytopenia. Balanced leukocytosis is practically nonexistent. Usually, only one (sometimes two) classes of leukocytes increase. Therefore, when the leukocyte count increases or decreases, it is important to evaluate which class of leukocytes experienced the increase or decrease. The absolute increase or decrease in the count of a specific class (lymphocytes, neutrophils) is crucial, not the percentage composition of the leukogram.
An increase in the leukocyte count is most commonly a result of bacterial infections (neutrophils predominating) or viral infections (lymphocytes predominating). Neutrophilic leukocytosis occurs when there are signs of tissue necrosis (surgical trauma, myocardial infarction, major blood vessel thrombosis, etc.), in connective tissue diseases. Sometimes leukocyte production is stimulated by a neoplastic process because mutated cancer cells can start producing hematopoietic factors. The most common paraneoplastic leukocytosis occurs with a predominance of neutrophils or monocytes. Eosinophilic leukocytosis is most commonly seen in allergies, helminthic infections, and certain skin diseases. Idiopathic leukocytosis is an extremely rare phenomenon. Leukocytosis always has a cause. Sometimes it may be only apparent leukocytosis. The analyzer detects it due to an increase in normoblast count. In such cases, there are rules for correcting the total leukocyte count. Leukocytosis, occurring due to acute leukemia, may involve additional pathological elements in the periphery (blasts, promyelocytes, normoblasts, etc.). Chronic lymphocytic leukemia is characterized by leukocytosis with an increase in lymphocytes (normal morphology).
A decrease in the leukocyte count, leukopenia, is most commonly due to a decrease in neutrophils. Leukopenia can be one of the key laboratory indicators that appear at the onset of severe pathological conditions. 1) Leukopenia caused by a viral process occurs due to upper respiratory tract inflammation. It is usually mild (2–3×109/l) and can involve up to 10% activated virus-specific lymphocytes (in infectious mononucleosis, there are more). This leukopenia disappears within 1–2 months. If leukopenia is detected in a child in the background of upper respiratory tract inflammation, with indistinctly palpable lymph nodes and liver, the patient should be reexamined several times. Further decrease in leukocyte or platelet count (even after the upper respiratory tract catarrh has passed) may necessitate bone marrow puncture; 2) Leukopenia can be caused by hyperthyroidism (additional tests TSH, FT4, anti-TPO); 3) Its cause may be iron-deficiency anemia (MCV, MCH, RDW, iron, TIBC, ferritin); 4) Chronic inflammatory, septic process (anemia of chronic diseases, fevers that were temporarily treated with antibiotics, tonsillitis, proteinuria, liver colic, etc.); 5) Hemolytic anemia (indirect bilirubin, haptoglobin, LDH, hemosiderin in urine, ERY in urine); 6) Megaloblastic or aplastic anemia (along with leukopenia, thrombocytopenia, increased MCV, MCH, RDW, decreased vitamin B12, folate concentration, etc., may be present). In this case, a bone marrow examination is necessary; 7) Leukopenia in 2–3-year-old children can be caused by abscesses, infectious processes, rickets; 8) Sudden onset leukopenia without clear causes, along with hair loss, morning polyarthralgia, significant elevation of ENG, ANA titers, should raise suspicion of lupus erythematosus; 9) Leukopenia without clear causes, in the absence of somatic dysfunction, may be due to aplasia or leukemia; in such cases, a bone marrow examination is necessary; 10) Alcoholism. This cause usually manifests with thrombocytopenia, increased carbohydrate-deficient transferrin (CDT) concentration, changes in liver enzymes (especially GGT), increased MCV, prolonged PT, and other laboratory and clinical signs; 11) Use of tranquilizers. The influence of tranquilizers and other sedative preparations on the leukocyte count can be confirmed only when leukopenia resolves after discontinuing the medication; 12) Congenital leukopenia or leukopenia innocens. It is detected incidentally, without any complaints. In this type of leukopenia, there are 3–4×109/l leukocytes, with lymphocytes predominating in the leukogram percentage. Bone marrow appears normal. In such cases, blood should still be tested twice a year. In the case of leukopenia innocens, the blood picture does not change for 3–4 years. However, other diseases can also start this way (leukopenia without clear clinical signs of illness): leukemia, myelofibrosis, chronic hepatitis.
Source | Handbook of Basic Laboratory Tests | Doctor of Medical Sciences Gintaras Zaleskis