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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)

 

Red blood cell count

Men

5.0 ± 0.5 × 1012/l

Women

4.3 ± 0.5 × 1012/l

Haemoglobin

Men

150 ± 20 g/l

Women

135 ± 15 g/l

Packed cell volume (PCV) or Haematocrit (Hct)

Men

0.45 ± 0.05 (l/l)

Women

0.41 ± 0.05 (l/l)

Mean cell volume (MCV)

Men and women

92 ± 9 fl

Mean cell haemoglobin (MCH)

Men and women

29.5 ± 2.5 pg

Mean cell haemoglobin concentration (MCHC)

Men and women

330 ± 15 g/l

Red cell distribution width (RDW)

As coefficient of variation (CV)

12.8 ±1.2%

As standard deviation (SD)

42.5 ± 3.5 fl

Red cell diameter (mean values)

Dry films

6.7–7.7 mm

Red cell density

1092–1100 g/l

Reticulocyte count

50–100 × 109/l (0.5–2.5%)

White blood cell count

4.0–10.0 × 109/l

Differential white cell count

Neutrophils

2.0–7.0 × 109/l (40–80%)

Lymphocytes

1.0–3.0 × 109/l (20–40%)

Monocytes

0.2–1.0 × 109/l (2–10%)

Eosinophils

0.02–0.5 × 109/l (1–6%)

Basophils

0.02–0.1 × 109/l (<1–2%)

Lymphocyte subsets (approximations from ranges in published data)

CD3

0.6–2.5 × 109/l (60–85%)

CD4

0.4–1.5 × 109/l (30–50%)

CD8

0.2–1.1 × 109/l (10–35%)

CD4/CD8 ratio

0.7–3.5

Platelet count

280 ± 130 × 109/l

Bleeding time

Ivy’s method

2–7 min

Template method

2.5–9.5 min

Prothrombin time

Recombinant

11–16 s

thromboplastin

10–12 s

Activated partial thombo-plastin time (APTT)

30–40 s

Thrombin time

15–19 s

Plasma fibrinogen

Clauss

2.0–4.0 g/l

Dry clot

1.5–4.0 g/l

Fibrinogen titre

≥ 128

Plasminogen

0.75–1.60 u/ml

Euglobulin lysis time

90–240 min

Antithrombin

0.75–1.25 u/ml

β-Thromboglobulin

<50 ng/ml

Platelet factor 4

<10 ng/ml

Protein C

Function

0.70–1.40 u/ml

Antigen

0.61–1.32 u/ml

Protein S

Total

0.78–1.37 u/ml

Free

0.68–1.52 u/ml

Activity

(MOREROWS)

Men

0.60–1.35 u/ml

Women

0.55–1.35 u/ml

Heparin cofactor II

0.55–1.45 u/ml

Median red cell fragility (MCF) (g/l NaCl)

Fresh blood

4.0–4.45 g/l NaCl

24h at 37°C

4.65–5.9 g/l NaCl

Cold agglutinin titre (4°C) <64

Blood volume (normalized to “ideal weight”)

Red cell volume

 

Men

30 ± 5 ml/kg

Women

25 ± 5 ml/kg

Plasma volume

45 ± 5 ml/kg

Total blood volume

70 ± 10 ml/kg

Red cell lifespan

120 ± 30 days

Serum iron

Men and Women

10–30 μmol/(c 0.6–1.7 mg/l)

Total iron-binding capacity

47–70 μmol/l (c 2.5–4.0 mg/l)

Transferrin saturation

16–50%

Ferritin

Men

15–300 μgl/l (median 100 μg/l)

Women

15–200 μg/l (median 40 μgl/l)

Serum vitamin B12

180–640 ng/l

Serum folate

3–20 μg/l (6.8–45 nmol/l)

Red Cell folate

160–640 μg/l (0.36–1.45 μmol/l)

Plasma haemoglobin

10–40 mg/l

Serum haptoglobin

Radial immunodiffusion

0.8–2.7 g/l

Haemoglobin binding capacity

0.3–2.0 g/l

Hb A2

2.2–3.5%

Hb F

<1.0%

Methaemoglobin

<2.0%

Sedimentation rate (mm in 1 hour at 20 ± 3°C)

Men

 

(MOREROWS)

17–50 yr

10 or <

51–60 yr

12 or <

61–70 yr

14 or <

>70 yr

30 or <

Women 17–50 yr

12 or <

(MOREROWS)

51–60 yr

19 or <

61–70 yr

20 or <

>70 yr

35 or <

Plasma viscosity

25°C

1.50–1.72 mPa/s

37°C

1.16–1.33 mPa/s

 

 

 

Haematological values for normal infants (amalgamation of data derived from various sources; expressed as mean ±2SD or 95% Range)

 

Birth

Day 3

Day 7

Day 14

1 Month

2 Months

3–6 Months

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

Haemoglobin g/l

180 ± 40

80 ± 30

175±4

165±4

140 ± 25

112 ± 18

126 ± 15

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

Mean cell volume (MCV) fl

110 ± 10

105 ± 13

107 ± 19

105 ± 19

104 ± 12

95 ± 8

76 ± 8

Mean cell Hb (MCH) pg

34 ± 3

34 ± 3

34 ± 3

34 ± 3

33 ± 3

30 ± 3

27 ± 3

Mean cell Hb conc (MCHC) g/l

330 ± 30

330 ± 40

330 ± 50

330 ± 50

330 ± 40

320 ± 35

330 ± 30

Reticulocytes × 109/l

120–400

50–350

50–100

50–100

20–60

30–50

40–100

White blood cell count (WBC) × 109/l

18 ± 8

15 ± 8

14 ± 8

14 ± 8

12 ± 7

10 ± 5

12 ± 6

Neutrophils × 109/l

4–14

3–5

3–6

3–7

3–9

1–5

1–6

Lymphocytes × 109/l

3–8

2–8

3–9

3–9

3–16

4–10

4–12

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

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

Lymphocyte subsets (× 109/l)[**]

CD3

 

3.1–5.6

 

 

 

2.4–6.5

2.0–5.3

CD4

 

2.2–4.3

 

 

 

1.4–5.6

1.5–3.2

CD8

 

0.9–1.8

 

 

 

0.7–2.5

0.5–1.6

CD4/CD8 ratio

 

1.1–4.5

 

 

 

1.1–4.4

1.1–4.2

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)

 

1 Year

2–6 Years

6–12 Years

Red cell count × 1012/l

4.5 ± 0.6

4.6 ± 0.6

4.6 ± 0.6

Haemoglobin g/l

126 ± 15

125 ± 15

135 ± 20

Packed cell volume (PCV) l/l

0.34 ± 0.04

0.37 ± 0.03

0.40 ± 0.05

Mean cell volume (MCV) fl

78 ± 6

81 ± 6

86 ± 9

Mean cell Hb (MCH) pg

27 ± 2

27 ± 3

29 ± 4

Mean cell Hb conc (MCHC) g/l

340 ± 20

340 ± 30

340 ± 30

Reticulocytes × 109/l

30–100

30–100

30–100

White cell count × 109/l

11 ± 5

10 ± 5

9 ± 4

Neutrophils × 109/l

1–7

1.5–8

2–8

Lymphocytes × 109/l

3.5–11

6–9

1–5

Monocytes × 109/l

0.2–1.0

0.2–1.0

0.2–1.0

Eosinophils × 109/l

0.1–1.0

0.1–1.0

0.1–1.0

Lymphocyte subsets (×109/l)[*]

CD3

1.5–5.4

1.6–4.2

0.9–2.5

CD4

1.0–3.6

0.9–2.9

0.5–1.5

CD8

0.6–2.2

0.6–2.0

0.4–1.2

CD4/CD8 ratio

1.0–3.0

0.9–2.7

1.0–3.0

Platelets × 109/l

200–550

200–490

170–450