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E - Haem > Red cell parameters > Flashcards

Red cell parameters Flashcards

1
Q

what are you looking for when assesssing RBC?

A
  • Red cell mass
    (PCV/Hct, RBCC, Hgb)
  • Evidence for effective and appropriate erythropoiesis
    size and colour (MCV, MCHC)
    reticulocyte count
  • Red cells size and variation
    (MCV, RDW)
  • Red cell haemoglobinisation (colour)
    MCHC
  • Red cell shapes and inclusions
    Smear
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2
Q

what does MCHC stand for and what does it mean?

A

Mean corpuscular hemoglobin concentration - how much haemoglobin is in the red cell

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3
Q

what is polycythaemia?

A

high number of red blood cells in blood
can be relavtive or absolute

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4
Q

what is relative polycythaemia?

A

Apparent increase in RBC due to a decrease in fluid in circulation (often increase total protein and albumin)
PCV has increased but not RBC production (dehydration)

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5
Q

what is absolute polycythaemia?

A

True increase in RBC mass due to increased RBC production/release (usu polychromasia, anisocytosis and reticulocytes)

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6
Q

what is the opposite of polycythaemia?

A

anaemia

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7
Q

what are the two types of anaemia?

A

regenerative or non-regenerative

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8
Q

what are the 5 cellular charateristics of anaemia?

A

normocytic, normochromic, hypochromic, macrocytic, microcytic

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9
Q

what is the other initials for packed cell volume?

A

Hct - hematocrit test

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10
Q

what are the three tests that tell you how many red cells there are? (red cell mass)

A

PCV, RBC Count, HgB conc
* All three are measures of red cell mass and oxygen carrying capacity
* Usually interpret them as a block
* All equally affected by haemoconcentration
* Will usually increase and decrease in line with one another
* When they are discordant (dont match) find out why – “rule of three”

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11
Q

why can PVC from an analyser be wrong?

A

PCV is calculated rather than measured in an analyser (PCV = MCV xRBCC)
PCV may be wrong if:
* RBC’s miscounted
* Mistaken for platelets
* Aggregated into pairs and triplets
* MCV misleading
* Cell shrinkage or swelling
* Transport, tube filling
* Osmotic effects in machine

MCV - mean corpuscular volume

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12
Q

why might the MCHC be high ?

A
  • Haemolysis (sample handling or intravascular) - Hgb is outside the cells
  • Lipaemia - interferes with light through sample, affects Hbg measuring

Not physiological to cram more Hgb into red cells than they will take

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13
Q

what are the reasons that MCV is wrong?

A
  • Swelling of transport
  • Mis-identification – pairs and triplets, cross over with large platelets
  • Cell shrinkage or expansion in sample e.g. hyperosmolar
  • Will impact on calculated PCV/HCT
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14
Q

what is the rule of three for red cell mass?

A

Hematocrit % approx = Hgb (g/dL) x3 (+/-3%)

or can be picked up by looking at the MCHC, will show when RBC, HCT and HGB are not mathcing

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15
Q

what is analysis results is the classifiction of anaemia based on?

A

Based on MCV and MCHC
* Blunt measure - a lot of immature cells (bigger) are needed before the average cell volume will increase enough to be outside of the reference limit - smear reading might be better at recognising immature cells
* Microscope visible findings may not be sufficient to push parameter out of reference range - this is why visual exam is important
* Machine dot-plots and histograms more sensitive

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16
Q

what is often the reason for normocytic normochromic anaemic?

A

illness or pre-regenerative or occasionally non-regenerative

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17
Q

what is the reason for macrocytic hypochromic anaemia, why is this the apperance/structure?

A

classic highly regenrative
- lots of immature larger RBC, normal amount of haemoglobin but due to larger space, the colour is pale

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18
Q

what is the reason for microcytic hypochromic anaemia?

A

iron deficiency, chronic external blood loss
there is not enough iron to make enoguh Hgb to stop the red cells devision - therefore small red cells

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19
Q

what is the reason dor microcytic hypochromic RBCs without anaemia?

A

portosystemic shunt - as iron not an avalible as it should be

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20
Q

what are the causes of absolute polycythaemia?

A
  • tumour
  • bone marrow
  • more erythropoietin (kidney tumour and hypoxia (altitude training))
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21
Q

Exercise, fear, excitement, severe pain - (stress ) can cause a relative polycythaemia, why is this?

A

Adrenaline secretion, splenic contraction and transient redistribution of RBC from the spleen to the circulation

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22
Q

what is the cause of primary polycythaemia (polucythaemia vera)?

A
  • rare myeloproliferative disorder (affecting) the bone marrow
  • abnormal response of RBC precursors
  • Normal EPO levels
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23
Q

what is the cause of secondary polycythaemia?

A
  • Chronic tissue hypoxia of renal tissues (low arterial pO2) due to:
    heart/lung diseases, high altitude, thrombosis, constriction of renal vessels
  • Renal tumor or cysts [↑intra-capsular pressure]
  • Increased EPO
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24
Q

why can Renal tumor or cysts cause seconday polycythaemia?

A

↑intra-capsular pressure - less blood able to pass through, sensors that check oxygention levels for erythropoietin production, think O2 deficiency therefore increases erythropoietin production and increaased RBCs

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25
Q

what are reticulocytes?

A

Young (immature/non-nucleated) erythrocytes prematurely released to blood from the bone marrow in regenerative anaemias.

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26
Q

what do you need to do inorder to visualies reticulocytes on smear?

A

New methylene blue (NMB) precipitation demonstrates RNA-protein complexes (ribosmal RNA & mitochondria).

Young red cells including reticulocytes have “polychromatophil” (bluer) appearance on Romanowsky (routine) stain

27
Q

why would you want to measure reticulocytes?

A
  • Evaluation of erythropoiesis in bone marrow.
  • Differentiation of regenerative and non-regenerative anaemia.
28
Q
A
29
Q

what are the two ways to obtain a reticulocyte count, and what reticulocyte count are we after, why is this helpful?

A

Reticulocyte count:
Manual
Automated (some haematological analysers)

Absolute Reticulocyte count (ARC) (x10^9/l)
= observed % reticulocytes x RBC (x10^12/l) x 10
-> Independent of variation of RBC numbers

30
Q

what are the two types of reticulocytes that cats have?

A

aggregates and punctate

31
Q

what type of reticulocytes do we use in cats when assesing if an anaemia is regenerative?

A

aggregate

32
Q

what is the normal % of reticulocytes in dogs?

A

< 1 %

33
Q

what is the minimum conc of recticulocytes seen in dogs with regenerative anaemia?

A

60x 10^9/L

34
Q

what is the normal % of reticulocytes in cats?

A

0.2 - 1.6%

35
Q

what is the minimum conc of aggregate recticulocytes seen in cats with regenerative anaemia?

A

50x 10^9/L

36
Q

what is the conc of reticulocytes in ruminants and horses in normal blood?

A

virtually no reticulocytes in normal blood - immature cells stay in bone marrow until developed

37
Q

do you see reticulocytes in serverely anaemic horses?

A

no, not often

38
Q

when is peak reticulocyte production in cattle following acute blood loss?

A

7-14 days post blood loss

39
Q

decribe these RBCs, what species do they come from?

A

dog:
Larger erythrocytes (platelets are smaller)
Uniform size
Central pallor

40
Q

describe these RBCs what species are they from?

A

cat:
Smaller erythrocytes (platelets are simillar size)
Anisocytosis (variation in size)
Scarce central pallor (less concave)

41
Q

decribe these RBCs, what species do they come from?

A

horse:
Rouleaux (stack due to discoid shape)
(sedimentation tendency)

42
Q

describe these RBCs, what species do they belong to?

A

runimant:
anisocytosis and crenation (scalloped or notched)

43
Q

what is the variation in RBC that some poodles have?

A

macrocytosis in some poodles

44
Q

what is the variations that akitas have on blood analysis?

A

small erythrocytes and high potassium content within RBCs (other species have high K but dogs don’t except akitas)

45
Q

what variation do greyhounds have on blood analysis?

A

high PCVs (0.55-0.6 L/L)

46
Q

what is the words for varriation in shape of RBCs?

A

Poikilocytosis

47
Q

what are codocytes and what do they mean?

A

target cells (bulls eye), sign of iron deficency

48
Q

what are spherocytes and what are they used to diagnose?

A

round RBCs that are smaller in diameter than normal RBCs, lack central pallor, and have a denser (hyperchromic) staining quality.

immune mediated haemolytic anaemia

49
Q

what are acanthocytes?

A

thawny/ spikey cells

50
Q

what are schistocytes?

A

broken cells

51
Q

what are echinocytes?

A

crenation - small spikes, ‘burr cell’
without any pathological significance

52
Q

what are howell jolly bodies?

A

inclusions within red cells - reminants of nuclear matterial

53
Q

what is basophillic stippling?

A

blue spotting throughout cytoplasma

54
Q

what is heinz bodies?

A

crystalised haemoglobin withing RBCs

55
Q

what are the 5 inculsions that can be found in RBCs?

A
  • Howell Jolly bodies
  • Basophilic stippling
  • Nucleated RBC’s
  • Infectious agents
  • Heinz bodies
56
Q

what is this an example of?

A

schistocytes - erthrocytes fragmented and broken

57
Q

what is this an example of?

A

acanthocytes - Few irregular elongations of RBC border with rounded ends

58
Q

what is this an example of?

A

crenation (echinocytes) - enen numerous pin-point projections
often dehydrated samples (small volume of blood in EDTA tube causes osmotic effect)

59
Q

what is rouleaux formation?

A

Clustering, sticky, piling of RBCs

60
Q

in what species is rouleaux formation normal?

A

horses

61
Q

what does rouleaux formation indicate is SA? why is this?

A

Indicates inflammation in small animals
Relates to increased “stickiness” of plasma with increased globulin content

62
Q

why is agglutination of RBCs seen?

A

Immune-mediated haemolytic anaemia
Mismatched blood transfusion

63
Q

what can you do to tell the difference between agglutination and rouleaux formation?

A

Mix 1 drop of blood with 1 drop of saline on slide
-> Agglutination will persist, rouleaux formation will disperse
the right image is agglutination

E - Haem (9 decks)

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