Blood count

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(Total) blood count (BC) is a routine screening test. It is performed at each admission to the hospital, as well as when a hematological or more serious infectious disease is suspected.

BC components:

Procedure and methods used[edit | edit source]

Venous blood is collected in a tube with EDTA. The numbers and relative proportions of the individual cell lines are analyzed using flow cytometry. Flow cytometry determines not only the number of cells of each cell type per unit volume but also the volumes of a given type. Some abnormal cells may be inaccurately identified (schistocytes, immature and leukemic forms of leukocytes). In case of suspicion of the presence of abnormal cell types, evaluation under a microscope by an experienced laboratory worker (so-called "manual" differential) is necessary.

Hb concentration is determined using colorimetry (= absorption spectrometry). Hct is determined after centrifugation of the sample as the ratio (percentage) of the condensed ("crushed") volume of cell elements (Ery + Leu + Tr) to the total volume. Erythrocyte parameters (MCV, MCH, MCHC) are calculated using simple equations.

Erythrocytes (left), thrombocytes (middle) and leukocytes (right)

Physiological values[edit | edit source]

Parameter Men Women Unit and commentary
Ery 5±0,7 4,6±0,7 × 106/µl (= 1012/l)
Hb 150±20 140±20 × g/l (also expressed in g/dL)
Hct 0,46±0,06 0,43±0,06 (or ×100 in percent)

Reticulocytes: 0,5–1,5%

  • It reflects the dynamics of changes in the number of erythrocytes. Decreased values ​​usually indicate anemia from underproduction, while increased values ​​indicate anemia from increased losses.
Parameter Calculation Value
MCV Hct/Ery 90±5fL
MCH Hb/Ery 31±3pg
MCHC MCH/MCV = Hb/Hct 34±3g/dl

MCV (mean corpuscular volume, mean erythrocyte volume),

  • divides anemia into microcytic, normocytic, and macrocytic.

MCH (mean corpuscular hemoglobin, the average amount of Hb in the cell),

  • divides anemia into hypochromic and normochromic.

MCHC (mean corpuscular hemoglobin concentration, mean concentration of Hb in erythrocytes).

RDW (erythrocyte distribution width): 11,5–14,5%,

  • provides an overview of variability in red blood cell size (anisocytosis).

Leu: 4000–10 000/µl (children about 25% more, toddlers – about 50% more)

Leukocyte differential count

Thrombocytes: 150 000–350 000/µl

Nomenclature of changes in the number of cells in BC[edit | edit source]

Cell type Rise Decline
Erythrocytes polyglobulia/polycythemia anemia
Leukocytes leukocytosis leukopenia
lymphocytes lymphocytosis lymphocytopenia
granulocytes granulocytosis granulocytopenia or even agranulocytosis
neutrophils neutrophilia neutropenia
eosinophils eozinophilia eozinopenia
Thrombocytes thrombocytosis thrombocytopenia
All blood lines pancytopenia

Causes of changes in blood counts[edit | edit source]

Red blood cell line[edit | edit source]

Parameter Increase Decreased[1]
Hemoglobin polycythemia, high altitude, hypoxia-related conditions, erythropoietin-producing tumors (e.g. renal cell carcinoma), stress states, smoking, dehydration anemia, hemolysis, renal insufficiency, blood loss, marrow aplasia, medication (chloramphenicol, gold), pregnancy (hemodilution predominates over only a slight increase in erythromass)
Erythrocyte count polycythemia, high altitude, heart disease, erythropoietin-producing tumors, stress, smoking, haemoconcentration anemia, haemolytic conditions, renal insufficiency, blood loss, marrow aplasia, toxic substances (benzene), drugs (chloramphenicol)
MCV B12 deficiency (pernicious anemia), folic acid deficiency, liver disease, alcohol abuse, myxedema, marrow aplasia, reticulocytosis (young forms of erythrocytes are larger), myelofibrosis (typical lacrimal erythrocytes – dacryocytes), drugs (anticonvulsants) Fe withdrawal, hemoglobinopathy (thalassemia), anemia of chronic diseases, sideroblastic anemia, lead poisoning
Erythrocyte distribution width higher MCV: deficiency of vitamin B12 or folic acid, liver disease, immunohemolytic anemia, cold agglutinin disease
lower MCV: sideropenia, DIC (disseminated intravascular coagulation), consumption coagulopathy and conditions associated with erythrocyte fragmentation (schistocytes), haemoglobinopathy
Reticulocyte count hemolytic anemia, acute blood loss, anemia during therapy aplastic anemia, anemia with impaired red line maturation, liver disease, post-transfusion conditions, conditions after chemotherapy

White blood cell line[edit | edit source]

Parameter Increased Decreased
Neutrophil count acute bacterial infections, acute and chronic myeloid leukemias, myeloproliferation, generalized malignancies, stress states – pain, cold, heat (so-called distributional leukocytosis with the transfer of leukocytes from the marginal pool to the circulating), tissue necrosis (myocardial infarction), vasculitis with acidosis, drugs (G-CSF and GM-CSF – granulocyte and granulocyte and macrophage colony-stimulating factors, lithium, corticoids, adrenaline), leukemoid reactions (over 30,000 segmented and younger granulocytes) in sepsis, endocarditis, miliary tuberculosis, and tumor metastasis viral infections, aplastic anemias, X-rays, agranulocytosis, immunosuppression, drugs (antibiotics, chemotherapeutics, thyrostatics, analgesics, psychotropic drugs), lymphatic and monocyte leukemias

CAVE! When evaluating neutropenias, the decrease in their absolute number is important.

Number of lymphocytes chronic infections, tuberculosis, chronic lymphadenosis, infectious mononucleosis, other virosis, chronic lymphadenosis, Hodgkin's disease, hypocorticalism, idiopathic proctocolitis, idiopathic thrombocytopenic purpura AIDS and related diseases, bone marrow damage after chemo- and radiotherapy, steroid treatment, hypercorticalism, aplastic anemia, neurological diseases (multiple sclerosis)
Monocyte count viral, protozoal and parasitic infections, granulomatous diseases (sarcoidosis, Crohn's disease), tumors (malignant lymphomas, monocyte leukemia)
Eosinophil count allergic diseases, bronchial asthma, parasitic infections (most often toxocariasis, trichinosis, and intestinal helminthiasis), drug allergies, collagenosis, angioneurotic edema, Hodgkin's disease and other generalized malignancies, skin diseases (urticaria, pemphigus)
Basophil count chronic myeloid leukemia, hypothyroidism, mastocytoma, event. systemic mastocytosis

Platelets[edit | edit source]

Parameter Increase Decreased[1]
Platelet count malignant disease (especially GIT), inflammatory bowel disease, conditions after splenectomy, myeloproliferative disease (thrombocythaemia, polycythemia vera), infections, after blood loss, sideropenia, pancreatitis hypersplenism (especially liver cirrhosis), marrow damage, alcohol, immune disorders (most commonly drug), infections (e.g. Helicobacter pylori), collagenosis, DIC and other consumptive coagulopathies, septic conditions

Physiological changes in blood count and in differential calculus in childhood[edit | edit source]

Hemoglobin gene expression before and after birth (data on Wood W.G., (1976). Br. Med. Bull. 32, 282.).

Normal levels of red and white blood cells in the peripheral blood in children vary with age.


In the perinatal period, hemoglobin (Hb) is composed of 80% fetal hemoglobin (HbF – chains α2 γ2) and 20% adult hemoglobin (HbA1 – chains α2 β2). After birth, fetal hemoglobin is exchanged for adult hemoglobin within 6-12 months.


In the first days after birth, short-term polyglobulia (relative polycythemia) with a hemoglobin concentration of about 195 g/l due to a reduction in blood volume, an increased reticulocyte count to 3% and erythrocyte macrocytosis is present. After the neonatal period, there is a steady decrease in hemoglobin levels due to attenuated erythropoiesis. At the age of 10 weeks, the lowest hemoglobin level is reached (up to 95 g/l, on average 115 g/l) – a phenomenon sometimes called "three-month anemia". This is followed by a steady increase until the adult values ​​reach puberty. The normal value of reticulocytes is around 1% and the lifespan of the erythrocyte in the blood is 120 days. In premature infants, the decrease in hemoglobin is more pronounced due to insufficient production of erythropoietin – "premature anemia". The decrease in Hb is compensated by shifting the oxygen dissociation curve to the right and easier delivery of oxygen to the tissues. The volume of erythrocytes also changes. After birth it is 119 fl (macrocytosis), then decreases to 70-77 fl at 6 months and gradually rises to 80-90 fl in adulthood.[2][3]

Normal values ​​of red blood count[4]
Age Hemoglobin (g/l) Hematocrit (%) Erythrocytes (1012/l) Reticulocytes (‰) MCV (μm3) Note
1 day 140–240 58–62 4,5–6,5 15–65 106±7 polyglobulia
1 month 110–170 30–37 3,9–5,3 3–13 100±6
3 months 100–130 30–37 3,2–4,3 10–35 88±6 "three-month anemia"
1 year 110–150 33–40 4,2–5,5 3–13 73±8
13–17 year-old men 130–160 39–47 4,8–5,7 1–13 78±8
13–17 year-old women 110–160 36–44 4,3–5,5 1–15 78±8

The number of leukocytes rises sharply during the first days of life to values around 20×109/l (leukocytosis formed by granulocytes – neutrophils, eosinophils, and basophils) – neutrophils with a shift to the left. After about one week, the number of leukocytes decreases again ("first crossing" on day 5)[3] and the predominance of lymphocytes (relative lymphocytosis) occurs by the age of 4, then the neutrophil/lymphocyte ratio equalizes and later granulocytes predominate until old age ("second crossing" in the 5th year). Monocytes make up 5-10% of the cells in the differential budget.[2][3]


The normal number is 140-400 × 109/l regardless of age, volume 7-11 fl and their life in the circulation 7-10 days.[3]

References[edit | edit source]

Related Articles[edit | edit source]

External links[edit | edit source]

References[edit | edit source]

  1. a b KRČ, I. HEMATOLOGIE – HODNOCENÍ KREVNÍHO OBRAZU. UROLÓGIA PRE PRAX [online]2007, vol. -, no. 5-6, p. 231-232, Available from <>. 
  2. a b MUNTAU, Ania Carolina. Pediatrie. 4. edition. Grada, 2009. pp. 233. ISBN 978-80-247-2525-3.
  3. a b c d LEBL, J – JANDA, J – POHUNEK, P. Klinická pediatrie. 1. edition. Galén, 2012. 698 pp. pp. 529-530. ISBN 978-80-7262-772-1.
  4. MUNTAU, Ania Carolina. Pediatrie. 4. edition. Grada, 2009. pp. XX. ISBN 978-80-247-2525-3.

Sources[edit | edit source]

  • NEČAS, Emanuel. Patologická fyziologie orgánových systémů, část I. 2. edition. Nakladatelství Karolinum, 2007. ISBN 978-80-246-1291-1.