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ANAEMIA

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Cut-off Hb for normal ranges are arbitrary.

Normal ranges depend on age,

environment, physiologic state

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Mechanisms of anaemia

Reduced red-cell production

defective precursor proliferation

defective precursor maturation

defective proliferation and maturation

Increased RBC destruction

RBC loss from circulation

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DEFECTIVE RBC PRODUCTION

Reduced proliferation of precursors

Fe-deficiency

Anaemia of chronic disorders; Ca, infection, inflammation

Reduced EPO production; renal disease

Reduced O2 requirements; hypothyroidism, hypopituitarism

Reduced O2 affinityfor Hb

Bone marrow disorders; aplasia, pure RBC aplasia,infiltrative disorders

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Defective maturation of precursors Nuclear maturation; B12def., folate def.,erythroleukaemia

Cytoplasmic maturation; Fe-def., dis. of globin synthesis,

dis. of haem or Fe- metabolism, dis. of porphyrin metab

Unknown mechanismsMDS

Infection eg. HIVCong. Dyserythropoietic anaemias

Toxins and chemicals

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Finding the cause of anaemia

RBC changes are the most important

clues- MCV, MCH, MCHC

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AUTOMATED CYTOMETRY

FLOW CYTOMETRY- High-speed jet of dilute suspension of blood cells flowing

perpendicularly to a sensor. The sensor may be impedance(electric

current) or light beam detector. As the cell passes through there is

interuption to the current or light beam that is proportional to cellsize, the magnitude of this interuption is recorded.

-Typically, 10,000 cells can be counted in 30-60secs and several

variables can be examined at the time.

-Data is displayed in histogram/scattergram form.

IMAGE ANALYSIS-High-speed optics analysis of fixed cells with memory of examined

cells.

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RBC volume distribution in

normals is symmetrical, and

can be analyzed by Gaussian

model/Log-normal model.

Biologic heterogeneity can bediscrete(>one sub group) or

non-discrete(one sub group)

RBC heterogeneity is

measured by the coefficient of

variation ie. The ratio of

SD(width of histogram) to the

MCV. RDW

50

25

00 30 60 90 120 150

R

elativeFrequen

cy(%)

Particle volume, fl.

RBC 5.23

Hb 15.5

Hct 47.8

MCV 91.4

RDW 11.9

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MICROCYTIC DISORDERS

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Similar changes seen in

thalassaemia, sideroblastic

anemia but RDW remains

normal.

Advanced Fe-deficiency with

abnormalities in all indices

Hypochromic,microcytic

100

50

Relative

Frequency

%

9050 120 Particlevolume, fl

RBC 3.19

Hb 6.4

Hct 20.5

MCV 64.4

RDW 18.0

MCH 20.5

MCHC 22.2

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NORMOCYTIC DISORDERS

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In anaemia of chronic disease

there is a failure of erythroid

proliferation, hence reduced

RBC count but normal

histogram.

MCV may be lower in a

minority but RDW should

remain normal.

Increased RDW distinguishes

Fe-deficiency from ACD and

heterozygous thalassemia

100

50

Relative

Frequency

%

9050 120 Particlevolume, fl

RBC 3.83

Hb 11.3

Hct 33.5

MCV 87.0

RDW 11.9

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MACROCYTIC DISORDERS

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Severe folate/Vit B 12

deficiency shows low RBC

count, high MCV, and

Increased RDW.

The essential defect in folate /

Vit B 12 deficiency is nuclear

maturation delay.

100

50

Relative

Frequency

%

9050 120 Particlevolume, fl

RBC 2.87

Hb 10.6

Hct 31.4

MCV 109.6

RDW 17.3

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HAEMOLYTIC DISORDERS

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Red cell fragmentation

Fragments form a plateau

to the left.

Because of fragments the

MCV is less than realvalue ( approx 90)

50

25

00 30 60 90 120 150

R

elativeFrequen

cy(%)

Particle volume, fl.

RBC 3.49

Hb 10.7

Hct 31.3

MCV 84.1

RDW 16.0

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50

25

00 30 60 90 120 150

R

elativeFrequen

cy(%)

Particle volume, fl.

In sickle cell anaemia and other

Haemoglobinopathies there is an

inverse correlation between Hb

level and RDW.Anisocytosis on blood smear

correlates with RDW of

automated counter.

The counter does not measure

shapes, therefore the striking

poikilocytosis on blood smear

appears severer than the

increase in RDW.

RBC 2.10

Hb 6.4

Hct 19.8

MCV 94.0

RDW 22.0

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Mechanisms of Haemolysis

Abnormalities of RBC membrane

Genetic: HS,elliptocytosis

Alteration in lipid content: CLD

Complement/Ig activation: Immune Increased permeability: G6PD def.

Increased rigidity

Aggregation of Hb eg. Hb SS

Decreased solubility of Hb eg. Hb C

Inclusion body (Heinz). Thal., unstable Hb, oxidant drugs

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Mechanical damage

External trauma eg.march, karate,

Turbulent flow eg. Cardiac valves/prosthesis

Cleavage by fibrin strands. microangiopathy

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Evidence of haemolysis

Red cell breakdown

Raised serum bilirubin,unconjugated and bound to

albumin

Increased urine/faecal urobilinogen

Reduced haptoglobin/haemopexin levels from RE

removal of saturated Hb-hapto complex.

Fragments, microspherocytes etc.

Intravascular breakdown Meth-Hb

Raised plasma Hb

Haemoglobinuria/haemosiderinuria

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Shortened red cell survival. 51Cr

Increased RBC production

Polychromasia, reticulocytosis, macrocytosis,

erythroid hyperplasia,

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