Hematology introduction
Hematology is a discipline concerned with the production, function, and disorders of blood cells and blood proteins.
Blood is a liquid consisting of plasma (water, electrolytes, nutrients, waste products, and many soluble proteins) in which red cells, platelets and a variety of white cells are suspended. Its volume is about 70 mL/kg or about 5L total in an average size adult. 40-50% of blood volume is occupied by red cells.
Important proteins in the blood are: Albumin, which contributes a large portion of the oncotic pressure of plasma.· Immunoglobulins (antibodies), which combat infection· A number of proteins involved in the clotting cascade.·
The cellular components of blood include: Red blood cells (RBC, about 5 x 106· / µL), which carry oxygen to tissues Platelets (about 250,000 / µL), which facilitate clotting.· White blood cells (WBC, about 5,000 / µL), which fight infection.
WBC can be further· subdivided into neutrophils, lymphocytes (T, B, and natural killer [NK] cells), monocytes, eosinophils, and basophils (listed in order of typical frequency).
One of the most common tests ordered by all medical specialties is the complete blood count, or CBC.
The clinical laboratory uses an analyzer that functions both as a spectrophotomer and a flow cytometer. This instrument can determine the concentration (count) of RBC, platelets and WBC, the hemoglobin (Hgb) concentration, and the mean size of the red cells (MCV). The flow cytometer can accurately distinguish and count the various types of WBC, which it reports as a “differential”. The hematocrit (Hct), which represents the percentage of blood volume occupied by red cells, is calculated from the RBC count and the MCV.
Haematological values for normal adults expressed as a mean ±2SD (95% range)
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Red blood cell count |
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Men |
5.0 ± 0.5 × 1012/l |
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Women |
4.3 ± 0.5 × 1012/l |
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Haemoglobin |
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Men |
150 ± 20 g/l |
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Women |
135 ± 15 g/l |
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Packed cell volume (PCV) or Haematocrit (Hct) |
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Men |
0.45 ± 0.05 (l/l) |
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Women |
0.41 ± 0.05 (l/l) |
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Mean cell volume (MCV) |
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Men and women |
92 ± 9 fl |
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Mean cell haemoglobin (MCH) |
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Men and women |
29.5 ± 2.5 pg |
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Mean cell haemoglobin concentration (MCHC) |
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Men and women |
330 ± 15 g/l |
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Red cell distribution width (RDW) |
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As coefficient of variation (CV) |
12.8 ±1.2% |
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As standard deviation (SD) |
42.5 ± 3.5 fl |
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Red cell diameter (mean values) |
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Dry films |
6.7–7.7 mm |
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Red cell density |
1092–1100 g/l |
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Reticulocyte count |
50–100 × 109/l (0.5–2.5%) |
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White blood cell count |
4.0–10.0 × 109/l |
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Differential white cell count |
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Neutrophils |
2.0–7.0 × 109/l (40–80%) |
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Lymphocytes |
1.0–3.0 × 109/l (20–40%) |
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Monocytes |
0.2–1.0 × 109/l (2–10%) |
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Eosinophils |
0.02–0.5 × 109/l (1–6%) |
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Basophils |
0.02–0.1 × 109/l (<1–2%) |
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Lymphocyte subsets (approximations from ranges in published data) |
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CD3 |
0.6–2.5 × 109/l (60–85%) |
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CD4 |
0.4–1.5 × 109/l (30–50%) |
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CD8 |
0.2–1.1 × 109/l (10–35%) |
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CD4/CD8 ratio |
0.7–3.5 |
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Platelet count |
280 ± 130 × 109/l |
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Bleeding time |
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Ivy’s method |
2–7 min |
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Template method |
2.5–9.5 min |
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Prothrombin time |
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Recombinant |
11–16 s |
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thromboplastin |
10–12 s |
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Activated partial thombo-plastin time (APTT) |
30–40 s |
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Thrombin time |
15–19 s |
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Plasma fibrinogen |
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Clauss |
2.0–4.0 g/l |
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Dry clot |
1.5–4.0 g/l |
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Fibrinogen titre |
≥ 128 |
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Plasminogen |
0.75–1.60 u/ml |
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Euglobulin lysis time |
90–240 min |
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Antithrombin |
0.75–1.25 u/ml |
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β-Thromboglobulin |
<50 ng/ml |
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Platelet factor 4 |
<10 ng/ml |
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Protein C |
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Function |
0.70–1.40 u/ml |
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Antigen |
0.61–1.32 u/ml |
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Protein S |
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Total |
0.78–1.37 u/ml |
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Free |
0.68–1.52 u/ml |
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Activity |
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(MOREROWS) |
Men |
0.60–1.35 u/ml |
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Women |
0.55–1.35 u/ml |
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Heparin cofactor II |
0.55–1.45 u/ml |
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Median red cell fragility (MCF) (g/l NaCl) |
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Fresh blood |
4.0–4.45 g/l NaCl |
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24h at 37°C |
4.65–5.9 g/l NaCl |
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Cold agglutinin titre (4°C) <64 |
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Blood volume (normalized to “ideal weight”) |
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Red cell volume |
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Men |
30 ± 5 ml/kg |
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Women |
25 ± 5 ml/kg |
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Plasma volume |
45 ± 5 ml/kg |
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Total blood volume |
70 ± 10 ml/kg |
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Red cell lifespan |
120 ± 30 days |
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Serum iron |
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Men and Women |
10–30 μmol/(c 0.6–1.7 mg/l) |
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Total iron-binding capacity |
47–70 μmol/l (c 2.5–4.0 mg/l) |
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Transferrin saturation |
16–50% |
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Ferritin |
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Men |
15–300 μgl/l (median 100 μg/l) |
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Women |
15–200 μg/l (median 40 μgl/l) |
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Serum vitamin B12 |
180–640 ng/l |
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Serum folate |
3–20 μg/l (6.8–45 nmol/l) |
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Red Cell folate |
160–640 μg/l (0.36–1.45 μmol/l) |
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Plasma haemoglobin |
10–40 mg/l |
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Serum haptoglobin |
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Radial immunodiffusion |
0.8–2.7 g/l |
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Haemoglobin binding capacity |
0.3–2.0 g/l |
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Hb A2 |
2.2–3.5% |
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Hb F |
<1.0% |
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Methaemoglobin |
<2.0% |
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Sedimentation rate (mm in 1 hour at 20 ± 3°C) |
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Men |
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(MOREROWS) |
17–50 yr |
10 or < |
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51–60 yr |
12 or < |
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61–70 yr |
14 or < |
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>70 yr |
30 or < |
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Women 17–50 yr |
12 or < |
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(MOREROWS) |
51–60 yr |
19 or < |
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61–70 yr |
20 or < |
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>70 yr |
35 or < |
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Plasma viscosity |
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25°C |
1.50–1.72 mPa/s |
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37°C |
1.16–1.33 mPa/s |
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Haematological values for normal infants (amalgamation of data derived from various sources; expressed as mean ±2SD or 95% Range)
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Birth |
Day 3 |
Day 7 |
Day 14 |
1 Month |
2 Months |
3–6 Months |
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Red blood cell count (RBC) × 1012/l |
6.0 ± 1.0 |
5.3 ± 1.3 |
5.1±1.2 |
4.9±1.3 |
4.2 ± 1.2 |
3.7 ± 0.6 |
4.7 ± 0.6 |
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Haemoglobin g/l |
180 ± 40 |
80 ± 30 |
175±4 |
165±4 |
140 ± 25 |
112 ± 18 |
126 ± 15 |
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Packed cell volume (PCV) l/l |
0.60 ± 0.15 |
0.56 ± 0.11 |
0.54 ± 0.12 |
0.51 ± 0.2 |
0.43 ± 0.10 |
0.35 ± 0.07 |
0.35 ± 0.05 |
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Mean cell volume (MCV) fl |
110 ± 10 |
105 ± 13 |
107 ± 19 |
105 ± 19 |
104 ± 12 |
95 ± 8 |
76 ± 8 |
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Mean cell Hb (MCH) pg |
34 ± 3 |
34 ± 3 |
34 ± 3 |
34 ± 3 |
33 ± 3 |
30 ± 3 |
27 ± 3 |
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Mean cell Hb conc (MCHC) g/l |
330 ± 30 |
330 ± 40 |
330 ± 50 |
330 ± 50 |
330 ± 40 |
320 ± 35 |
330 ± 30 |
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Reticulocytes × 109/l |
120–400 |
50–350 |
50–100 |
50–100 |
20–60 |
30–50 |
40–100 |
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White blood cell count (WBC) × 109/l |
18 ± 8 |
15 ± 8 |
14 ± 8 |
14 ± 8 |
12 ± 7 |
10 ± 5 |
12 ± 6 |
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Neutrophils × 109/l |
4–14 |
3–5 |
3–6 |
3–7 |
3–9 |
1–5 |
1–6 |
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Lymphocytes × 109/l |
3–8 |
2–8 |
3–9 |
3–9 |
3–16 |
4–10 |
4–12 |
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Monocytes × 109/l |
0.5–2.0 |
0.5–1.0 |
0.1–1.7 |
0.1–1.7 |
0.3–1.0 |
0.4–1.2 |
0.2–1.2 |
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Eosinophils × 109/l |
0.1–1.0 |
0.1–2.0 |
0.1–0.8 |
0.1–0.9 |
0.2–1.0 |
0.1–1.0 |
0.1–1.0 |
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Lymphocyte subsets (× 109/l)[**] |
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CD3 |
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3.1–5.6 |
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2.4–6.5 |
2.0–5.3 |
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CD4 |
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2.2–4.3 |
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1.4–5.6 |
1.5–3.2 |
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CD8 |
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0.9–1.8 |
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0.7–2.5 |
0.5–1.6 |
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CD4/CD8 ratio |
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1.1–4.5 |
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1.1–4.4 |
1.1–4.2 |
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Platelets × 109/l |
100–450 |
210–500 |
160–500 |
170–500 |
200–500 |
210–650 |
200–550 |
Haematological values for normal children (amalgamation of data derived from various sources; expressed as mean ±2SD or 95% Range)
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1 Year |
2–6 Years |
6–12 Years |
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Red cell count × 1012/l |
4.5 ± 0.6 |
4.6 ± 0.6 |
4.6 ± 0.6 |
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Haemoglobin g/l |
126 ± 15 |
125 ± 15 |
135 ± 20 |
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Packed cell volume (PCV) l/l |
0.34 ± 0.04 |
0.37 ± 0.03 |
0.40 ± 0.05 |
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Mean cell volume (MCV) fl |
78 ± 6 |
81 ± 6 |
86 ± 9 |
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Mean cell Hb (MCH) pg |
27 ± 2 |
27 ± 3 |
29 ± 4 |
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Mean cell Hb conc (MCHC) g/l |
340 ± 20 |
340 ± 30 |
340 ± 30 |
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Reticulocytes × 109/l |
30–100 |
30–100 |
30–100 |
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White cell count × 109/l |
11 ± 5 |
10 ± 5 |
9 ± 4 |
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Neutrophils × 109/l |
1–7 |
1.5–8 |
2–8 |
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Lymphocytes × 109/l |
3.5–11 |
6–9 |
1–5 |
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Monocytes × 109/l |
0.2–1.0 |
0.2–1.0 |
0.2–1.0 |
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Eosinophils × 109/l |
0.1–1.0 |
0.1–1.0 |
0.1–1.0 |
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Lymphocyte subsets (×109/l)[*] |
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CD3 |
1.5–5.4 |
1.6–4.2 |
0.9–2.5 |
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CD4 |
1.0–3.6 |
0.9–2.9 |
0.5–1.5 |
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CD8 |
0.6–2.2 |
0.6–2.0 |
0.4–1.2 |
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CD4/CD8 ratio |
1.0–3.0 |
0.9–2.7 |
1.0–3.0 |
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Platelets × 109/l |
200–550 |
200–490 |
170–450 |
