Anaemia(Cell Counts)

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Introduction to Haematology

Haematology The study of blood forming tissues and circulating blood components.

Functions of Blood:

1) Deliver nutrients, oxygen and hormones to tissues2) Collect aste from cellular metabolism!) Deliver cells to tissues for protection against the external environment

") To prevent lea#age by closing holes in blood vessels

Circulating blood accounts for $%&' of total body eight and is composed of cellular and

fluid elements.

Cellular elements:

(ed blood cells

hite blood cells

*latelets

Fluid elements:

*lasma vs. serumater

+lectrolytes

*roteins e.g. clotting factors, antibodies and transport proteins

Diagnosis of haematological disorders:

History ith emphasis on bleeding, infections and constitutional symptoms+xposure to toxins or chemicals

(evie of systemsamily history

Physical examination s#in, mucosae, eyes, organomegaly, lymphadenopathy, bony

tenderness.

Peripheral blood measurements

-anual vs. automated

Specimen collection

lood is collected in tubes that contain anticoagulant%+DT/, Trisodium citrate and

heparin(atio of blood to anticoagulant must be appropriate

lood can be stored for testing at a later time BUTstorage conditions must be

appropriate

(e0uest forms must be accurately and completely filled out

Cell counts

-anual % -ay be imprecise and technically time consuming

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;mmature C include bands, metamyelocytes, myelocytes, promyelocytes and blasts.

one marro examination

Cytology prepared from bone marro aspirate

Cellularity and infiltration assessed from bone marro biopsy

Indications for bone marrow assessment

+valuation of primary bone marro tumors

4taging of tumors/ssessment of abnormalities seen on the peripheral blood smear

/ssessment of infectious disease processes

+valuation of metabolic storage diseases

Sites for bone marrow evaluation

/nterio%medial tibia in children

4ternum

/nterior and posterior iliac crest

Staining of bone marrowright or -ay%6runald%6iemsa stain

aematoxylin and eosin for biopsy

4pecial stains Cytochemical stains ;mmunohistochemical stains

Cytogenetics

Erythrocyte sedimentation rate+4( commonly done but nonspecific

(eflects the tendency of blood to settle more rapidly in some disease states;ncrease in rate is related to increases in plasma fibrinogen, immunoglobulins and otheracute phase reactive proteins

(ed cell shape and numbers may also affect rate of fall

;ncreases ith age in otherise healthy people*oor screening test in asymptomatic individuals

5seful in folloing the course of disease e.g. (./., odg#in


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Definition

/naemia is a disorder in hich the patient suffers from tissue hypoxia due to a reductionin the oxygen%carrying capacity of the blood. The underlying problem is a decreased redcell mass, but it is demonstrated in clinical practice by a reduction in the haemoglobin

concentration or red cell count belo the loer limit of normal for the age and gender of

the patient./naemia is a sign of an underlying pathology >it is not a diagnosis) hose recognition

re0uires an approach to the hole patient for the delineation of the mechanism and

causes>s) of the red cell deficit.

#ormal &alues

;n order to identify the anaemic state one needs to have #noledge of the normal

haematological values.

Red cell count

-en $.$ 1.7 x 1712=lomen ".? 1.7 x 1712=l

;nfants >full%term, cord blood) $.7 1.7 x 1712=l

Children, 1 year "." 7.? x 1712=lChildren, 17%12 years ".& 7.& x 1712=l

Haemoglobin-en 1$.$2.$ g=dl

omen 1".7 2.$ g=dl;nfants >full%term, cord blood) 1@.$ !.7 g=dl

Children, 1year 12.7 1.7 g=dlChildren, 17%12 years 1!.7 1.$ g=dl

Paced cell volume !PC"# haematocrit$

-en 7."& 7.7& >l=l)

omen 7."2 7.7$ >l=l);nfants >full%term, cord blood) 7.$" 7.17 >l=l)Children, ! months 7.!? 7.7@ >l=l)

Children, 17%12 years 7."1 7.7" >l=l)

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Classification

There are to main classifications of anaemiaA1) the pathogenetic and aetiological classification, based on the cause of the anaemiaB

2) the morphological classification based on the characteristics of the red cell.

These to classifications are complimentary to each other, as the clinical investigation ofa patient ith anaemia involves to distinct stepsA

1) determination of the morphological type of anaemia and

2) determination of the cause of the anaemia.

The aetiological classificationof anaemia can be further subdivided into either

>a) hypo%regenerative or >b) hyper%regenerative.The presence of anaemia may result from the failure of bone marro production of red

cells >hypo%regenerative) or increase in red cell destruction or consumption ith a

concomitant increase in red cell production >hyper%regenerative).

'eticulocytes

+ach day approximately 7.?' of the red cell pool needs be replaced by young

erythrocytes released from the marro.

(eticulocytes are larger than mature red cells and contain portions of polyribosomal

(9/ material. 4upravital stains of peripheral blood detect these reticulated cells, andtheir number permits an assessment of the marro


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(ed Cell *roduction

The ma8or factor controlling the rate of red cell production is the oxygen content of thearterial bloodB a decrease in oxygen content stimulates erythropoiesis hile an increase

depresses it.

The red cell mass is maintained ithin the prescribed limits through the regulatoryfeedbac# stimulus of the humoral factor erythropoietin.hen the cause of anaemia is blood loss or haemolytic destruction in the peripheral

blood, erythropoietin overdrive of the marro leads to reticulocytosis.

(eticulocytes released under heavy erythropoeitin stimulation remain in the peripheralblood longer than the usual one%day maturation time of Enonstress reticulocytes') x *atient *CF >1=1) x 1 9ormal *CF >1=1) -aturation time >days)

The maturation of reticulocytes in the circulation isA1.7 day hen the *CF is 7."$ l=l,

1.$ days hen the *CF is 7.!$ l=l,

2.7 days hen the *CF is 7.2$ 1=1,2.$ days hen the *CF is 7.1$ l=l.

e.g. reticulocyte count 27'

*CF >patient) 7.2$ l=l*CF >normal) 7."$ l=l

-aturation time 2.7 days

'I * +, x ,-+. * .-.

+-, ,-/.

(; G2 ypo%regenerative anaemia(; H! yper%regenerative anaemia

%orphological Classification

/n alternative classification of anaemia is based on the morphology of the red cells,

usually their si3e and staining characteristics.

(ed cells may be normal in si3e >normocytic), large >macrocytic), or small >microcytic).

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*aresthesias and neurological deficits are common in pernicious anaemia.

>e) /limentary 4ystem6astrointestinal symptoms are fre0uent in anaemic patients.

4ome are manifestations of the disorder underlying the anaemia e.g.

duodenal ulcersB others may be a conse0uence of the anaemic conditionhatever the cause. 6lossitis and atrophy of the papillae of the tonguecommonly occur in nutritional anaemia.

>f) ever hen anaemia is severe, fever of mild degree may occur ithout cause,

other than the anaemia.

Compensatory Physiological "d1ustments to "naemia

The main function of haemoglobin is to transport oxygen from the lungs to the tissues./naemia reduces the oxygen%carrying capacity of the blood and results in tissue hypoxia.

This hypoxia causes dysfunction of the blood


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;ncreasing or decreasing oxygen affinity is associated ith shifts of the

oxygen%dissociation curve to the left or right respectively. The partialpressure of oxygen hen its saturation is $7' is 2& mmg.

The binding and release of oxygen by haemoglobin are profoundly affected by the

variations in the concentration of phosphates, especially 2,! diphosphoglyceric acid>2,!D*6). /n increase in red cell levels of 2,! D*6 is found in chronic anaemia. This

increase facilitates the delivery of oxygen to the tissues by reducing the affinity of

haemoglobin for oxygen at the oxygen tensions found in capillaries. The oxygen%dissociation curve is then shifted to the right.

2) Circulation

Cardiac compensation includes an increase in cardiac output and in the rate ofcirculation of the blood. This is brought about mainly by an increase in the stro#evolume of the heart but to a lesser extent by an increase in the heart rate. hen

the haemoglobin falls belo & g=dl the cardiac output is usually increased, hen it

is less than $g=dl an increase in stro#e volume and to a lesser extent in heart rateespecially ith exercise.

The total blood volume is #ept normal by the expansion of the plasma volume, in

order to maintain an ade0uate circulation.

!) There is redistribution of blood flo aay from tissues having lesser oxygen

re0uirements to those ith greater oxygen re0uirement. Thus s#in flo is

decreased hile cerebral and muscle flo are increased.

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The compensatory mechanisms commonly allo the patient to remain asymptomatic at

rest but exertion may produce symptoms as a result of the increased oxygen

re0uirements.

%anagement

;n the investigation of the patient suspected of being anaemic three 0uestions must beansered.1) ;s the patient anaemicJ

2) hat is the type of anaemiaJ

!) hat is the cause of the anaemiaJ

The principles of management of the anaemic patient areA

1) treatment of the disorder causing the anaemia and2) treatment of the anaemia.

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Anaemia(Cell Counts)