- •Preface
- •Contents
- •Procedures, Assays, and Normal Values
- •Normal Cells of the Blood and Hematopoietic Organs
- •The Individual Cells of Hematopoiesis
- •Bone Marrow: Cell Composition and Principles of Analysis
- •Abnormalities of the White Cell Series
- •Predominance of Mononuclear Round to Oval Cells
- •Prevalence of Polynuclear (Segmented) Cells
- •Erythrocyte and Thrombocyte Abnormalities
- •Hypochromic Anemias
- •Normochromic Anemias
- •Hyperchromic Anemias
- •Erythrocyte Inclusions
- •Thrombocyte Abnormalities
- •Cytology of Organ Biopsies and Exudates
- •Lymph Node Cytology
- •Branchial Cysts and Bronchoalveolar Lavage
- •Cytology of Pleural Effusions and Ascites
- •Cytology of Cerebrospinal Fluid
- •Introduction to the Physiology and Pathophysiology of the Hematopoietic System
- •Cell Systems
- •Principles of Regulation and Dysregulation in the Blood Cell Series and their Diagnostic Implications
- •Procedures, Assays, and Normal Values
- •Taking Blood Samples
- •Erythrocyte Count
- •Hemoglobin and Hematocrit Assay
- •Calculation of Erythrocyte Parameters
- •Red Cell Distribution Width (RDW)
- •Reticulocyte Count
- •Leukocyte Count
- •Thrombocyte Count
- •Significance of the Automated Blood Count
- •Bone Marrow Biopsy
- •Lymph Node Biopsy and Tumor Biopsy
- •Step-by-Step Diagnostic Sequence
- •The Individual Cells of Hematopoiesis
- •Eosinophilic Granulocytes (Eosinophils)
- •Basophilic Granulocytes (Basophils)
- •Monocytes
- •Lymphocytes (and Plasma Cells)
- •Megakaryocytes and Thrombocytes
- •Bone Marrow: Medullary Stroma Cells
- •Abnormalities of the White Cell Series
- •Predominance of Mononuclear Round to Oval Cells
- •Reactive Lymphocytosis
- •Relative Lymphocytosis Associated with Granulocytopenia (Neutropenia) and Agranulocytosis
- •Monocytosis
- •Acute Leukemias
- •Neutrophilia without Left Shift
- •Reactive Left Shift
- •Osteomyelosclerosis
- •Elevated Eosinophil and Basophil Counts
- •Clinically Relevant Classification Principle for Anemias: Mean Erythrocyte Hemoglobin Content (MCH)
- •Hypochromic Anemias
- •Iron Deficiency Anemia
- •Hypochromic Infectious or Toxic Anemia (Secondary Anemia)
- •Hypochromic Anemia with Hemolysis
- •Normochromic Anemias
- •Normochromic Hemolytic Anemias
- •Cytomorphological Anemias with Erythrocyte Anomalies
- •Bone Marrow Aplasia
- •Hyperchromic Anemias
- •Erythrocyte Inclusions
- •Hematological Diagnosis of Malaria
- •Thrombocyte Abnormalities
- •Thrombocytopenia
- •Lymph Node Cytology
- •Sarcoidosis and Tuberculosis
- •Non-Hodgkin Lymphoma
- •Metastases of Solid Tumors in Lymph Nodes or Subcutaneous Tissue
- •Branchial Cysts
- •Cytology of Pleural Effusions and Ascites
- •Cytology of Cerebrospinal Fluid
- •References
- •Index
Procedures, Assays, and Normal Values |
9 |
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Procedures, Assays, and Normal Values
Taking Blood Samples
Since cell counts are affected by the state of the blood circulation, the conditions under which samples are taken should be the same so far as possible if comparable values are desired.
This means that blood should always be drawn at about the same time of day and after at least eight hours of fasting, since both circadian rhythm and nutritional status can affect the findings. If strictly comparable values are required, there should also be half an hour of bed rest before the sample is drawn, but this is only practicable in a hospital setting. In other settings (i.e., outpatient clinics), bringing portable instruments to the relaxed, seated patient works well.
A sample of capillary blood may be taken when there are no further tests that would require venous access for a larger sample volume. A wellperfused fingertip or an earlobe is ideal; in newborns or young infants, the heel is also a good site. If the circulation is poor, the blood flow can be increased by warming the extremity by immersing it in warm water. Without pressure, the puncture area is swabbed several times with 70% alcohol, and the skin is then punctured firmly but gently with a sterile disposable lancet. The first droplet of blood is discarded because it may be contaminated, and the ensuing blood is drawn into the pipette (see below). Care should be taken not to exert pressure on the tissue from which the blood is being drawn, because this too can change the cell composition of the sample.
Obviously, if a venous blood sample is to be taken for the purposes of other tests, or if an intravenous injection is going to be performed, the blood sample for hematological analysis can be taken from the same site. To do this, the blood is allowed to flow via an intravenous needle into a specially prepared (commercially available) EDTA-treated tube. The tube is filled to the 1-ml mark and then carefully shaken several times. The very small amount of EDTA in the tube prevents the blood from clotting, but can itself be safely ignored in the quantitative analysis.
10 Physiology and Pathophysiology of Blood Cells
Erythrocyte Count
Up to 20 years ago, blood cells were counted “by hand” in an optical counting chamber. This method has now been almost completely abandoned in favor of automated counters that determine the number of erythrocytes by measuring the impedance or light dispersion of EDTA blood (1 ml), or heparinized capillary blood. Due to differences in the hematocrit, the value from a sample taken after (at least 15 minutes’) standing or physical activity will be 5–10% higher than the value from a sample taken after 15 minutes’ bed rest.
Hemoglobin and Hematocrit Assay
Hemoglobin is oxidized to cyanmethemoglobin by the addition of cyanide, and the cyanmethemoglobin is then determined spectrophotometrically by the automated counter. The hematocrit describes the ratio of the volume of erythrocytes to the total blood volume (the SI unit is without dimension, e.g., 0.4).
The EDTA blood is centrifuged in a disposable capillary tube for 10 minutes using a high-speed microhematocrit centrifuge (reference method). The automated hematology counter determines the mean corpuscular or cell volume (MCV, measured in femtoliters, fl) and the number of erythrocytes. It calculates the hematocrit (HCT) using the following formula:
HCT = MCV (fl)!number of erythrocytes (106/µl).
Calculation of Erythrocyte Parameters
The quality of erythrocytes is characterized by their MCV, their mean cell hemoglobin content (MCH), and the mean cellular hemoglobin concentration (MCHC).
MCV is measured directly using an automated hemoglobin analyzer, or is calculated as follows:
Hematocrit (l/l)
MCV " Number of erythrocytes (106/µl)
MCH (in picograms per erythrocyte) is calculated using the following formula:
Hemoglobin (g/l)
MCH (pg) " Number of erythrocytes (106/µl)
Procedures, Assays, and Normal Values |
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MCHC is determined using this formula:
MCHC (g/dl) " Hemoglobin concentration (g/dl) Hematocrit (l/l)
Red Cell Distribution Width (RDW)
Modern analyzers also record the red cell distribution width (cell volume distribution). In normal erythrocyte morphology, this correlates with the Price-Jones curve for the cell diameter distribution. Discrepancies are used diagnostically and indicate the presence of microspherocytes (smaller cells with lighter central pallor).
Reticulocyte Count
Reticulocytes can be counted using flow cytometry and is based on the light absorbed by stained aggregates of reticulocyte organelles. The data are recorded as the number of reticulocytes per mill (‰) of the total number of erythrocytes. Reticulocytes can, of course, be counted in a counting chamber using a microscope. While this method is not particularly laborious, it is mostly employed in laboratories that often deal with or have a special interest in anemia. Reticulocytes are young erythrocytes immediately after they have extruded their nuclei: they contain, as a remainder of aggregated cell organelles, a net-like structure (hence the name “reticulocyte”) that is not discernible after the usual staining procedures for leukocytes, but can be observed after vital staining of cells with brilliant cresyl blue or new methylene blue. The staining solution is mixed in an Eppendorf tube with an equal volume of EDTA blood and incubated for 30 minutes. After repeated mixing, a blood smear is prepared and allowed to dry. The sample is viewed using a microscope equipped with an oil immersion lens. The ratio of reticulocytes to erythrocytes is determined and plotted as reticulocytes per 1000 erythrocytes (per mill).
Normal values are listed in Table 2, p. 12.
Table 2 Normal ranges and mean values for blood cell components*
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Adults |
Newborns |
Toddlers |
Children |
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# 18 years old |
1 months |
2 years old |
10 years old |
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Leukocytes/µl |
MV |
7000 |
11000 |
10000 |
8000 |
or 106/l** |
NR |
4300–10000 |
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Band granulocytes % |
MV |
2 |
5 |
3 |
3 |
|
NR |
0–5 |
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|
|
Segmented neutrophilic |
MV |
60 |
30 |
30 |
30 |
granulocytes |
NR |
35–85 |
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|
absolute ct./µl |
MV |
3650 |
3800 |
3500 |
4400 |
or 106/l** |
NR |
1850–7250 |
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|
Lymphocytes % |
MV |
30 |
55 |
60 |
40 |
absolute ct./µl |
NR |
20–50 |
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|
MV |
2500 |
6000 |
6300 |
3100 |
|
or 106/l** |
NR |
1500–3500 |
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Monocytes % |
MV |
4 |
6 |
5 |
4 |
absolute ct./µl |
NR |
2–6 |
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or 106/l** |
MV |
450 |
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|
NR |
70–840 |
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Eosinophilic granulocytes (%) |
MV |
2 |
3 |
2 |
2 |
absolute ct./µl |
NR |
0–4 |
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MV |
165 |
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or 106/l** |
NR |
0–400 |
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Cells Blood of Pathophysiology and Physiology 12
Basophilic granulocytes (%) |
MW |
0.5 |
|
0.5 |
0.5 |
0.5 |
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NR |
0–1 |
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Male |
Female |
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Erythrocytes 106/µl |
MV |
5.4 |
4.8 |
4.7 |
4.7 |
4.8 |
or 1012/l** |
NR |
4.6–5.9 |
4.2–5.4 |
3.9–5.9 |
3.8–5.4 |
3.8–5.4 |
Hb g/dl |
MV |
15 |
13 |
17 |
12 |
14 |
or 10 g/l** |
NR |
14–18 |
12–16 |
15–18 |
11–13 |
12–15 |
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HKT |
MV |
0.45 |
0.42 |
44 |
37 |
39 |
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NR |
0.42–0.48 |
0.38–0.43 |
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MCH " HbE (pg) |
MV |
|
29 |
33 |
27 |
25 |
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NR |
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26–32 |
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MCV/µm3 |
MV |
|
87 |
91 |
78 |
80 |
or fl** |
NR |
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77–99 |
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MCHC g/dl |
MV |
|
33 |
35 |
33 |
34 |
or 10 g/l |
NR |
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33–36 |
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Erythrocyte, diameter (µm) |
MV |
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7.5 |
8.1 |
7.3 |
7.4 |
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Reticulocytes (%) |
MV |
16 |
24 |
7.9 |
7.1 |
7.6 |
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NR |
8–25 |
8–40 |
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Thrombocytes 103/µl |
MV |
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180 |
155–566 |
286–509 |
247–436 |
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NR |
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140–440 |
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MV " mean value, NR " normal range (range for 95% of the population, reference range), ct. count, ** SI units give the measurements per liter.
* For technical reasons, data may vary considerably between laboratories. It is therefore important also to consult the reference ranges of the chosen laboratory.
13 Values Normal and Assays, Procedures,