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LCB2 > Erythroid > Flashcards

Erythroid Flashcards

1
Q

List the components of blood

A
  • Fluid (plasma/serum)
  • Ions
  • Proteins (albumin, globulin, hormones, mediators, clotting factors, nutrients)
  • Lipids
  • Carbohydrates
  • Gas
  • Cells
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2
Q

List the functions of blood

A
  • Transport: nutrients, oxygen, waste removal, hormones and other mediators
  • Fluid/electrolyte haemostasis
  • coagulation
  • thermoregulation
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3
Q

What are reticulocytes?

A

Immature non-nucleated erythrocytes prematurely release to blood from bone marrow in regenerative anaemias. Names based on stain used - DiffQuik = polychromatophils, NMB = reticulocytes

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4
Q

Describe the appearance of reticulocytes

A
  • Romanowsky stains: Polychromatic, blue-pink mixed colour due to staining of ribosomes and haemoglobin
  • Using new methylene blue stain: precipitation demonstrates RNA protein complexes
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5
Q

What is the clinical relevance of reticulocytes?

A
  • Evaluation of erythropoiesis in bone marrow

- Differentiation of regenerative and non-regenerative anaemia

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6
Q

What is the absolute reticulocyte count?

A

The observed percentage of reticulocytes x RBC and is independent of variation of RBC numbers, ggiven as x10^9/l

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7
Q

What are the methods for the assessment of reticulocyte production?

A
  • Reticulocyte count (gives percentage)
  • Absolute reticulocyte count
  • Reticulocyte production index (sometimes used in dogs, going out of favour)
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8
Q

What are the 2 patterns of reticulocyte staining in cats?

A
  • Aggregate

- Punctate

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9
Q

Describe the dog-specific reticulocyte response (normal vs regerenative anaemia)

A
  • Low number of reticulocyte (<1%) in a healthy animal
  • Little regerenation of RBCs needed (live for ~100 days)
  • > 60x10^9/l in regenerative anaemia (>10 polychromatic cells per oil immersion field)
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10
Q

Describe the cat specific reticulocyte response (normal vs regenerative anaemia)

A
  • Low numbers normally ().2-1.6%)
  • Aggregate = 0.5% of erythrocytes, punctate = 1-10%
  • .50x10^9/l in regenerative anaemia
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11
Q

Which type of reticulocyte is considered in cats in the assessment of regeneration?

A

Aggregate

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12
Q

Compare the appearance of aggregate and punctate reticulocytes

A
  • Aggregate: blue stained, coarse clumping

- Punctate: small, blue stained dots

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13
Q

Describe the ruminant and hose specific reticulocyte response (normal and anaemia)

A
  • Virtually no reticulcytes in normal blood, can regenerate when have anaemia but generally do not release these into blood in normal animal
  • Reticulocytes may not appear even in very severe anaemias in horses
  • In cattle, peak production 7-14 days post acute blood loss
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14
Q

Compare the platelet size in dogs and cats

A

Platelet vs RBC size differs more in dog than cat

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15
Q

Outline some haematological variations within dog breeds

A
  • Macrocytosis in some poodles
  • Akitas have unusually small erythrocytes and particularly high potassium content
  • Greyhounds have high PCVs (0.55-0.6l/L)
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16
Q

What is red blood cell size measured by?

A

MCV (fL) = mean corpuscular volume = PCV (L/L) x1000/RBC count (10^12/L)

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17
Q

What conditions are indicated by macrocytosis of RBCs?

A
  • Regenerative anaemia
  • FeLV infection
  • Myeloproliferative disease
  • Normal in poodles
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18
Q

What does hypochromic macrocytosis indicate?

A

Regenerative anaemia haemorrhage, haemolysis)

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19
Q

What does normochromic macrocytosis indicate?

A

Non-regenerative anaemia, assocaited with FeLV usubgroup A in kittens and myeloproliferative disorders in dogs and cats

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20
Q

What does hypochromic microcytosis indicate?

A
  • With anaemia: classic iron deficinecy, chronic external blood loss
  • Without anaemia: portosystemic shunts
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21
Q

What is the most common cause of iron deficiency in dogs?

A

Occult loss from GIT

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22
Q

Explain how microcytosis occurs as a result of iron deficiency

A
  • At a certain haemoglobin concentration this triggers the cell to stop dividing
  • Where this takes longer to reach due to deficiency,t he cell will continue to get smaller until the correct concentration is reached
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23
Q

What conditions may cause microcytosis?

A
  • Iron deficiency
  • Altered iron metabolism
  • Dogs/cats with portosystemic shunts
  • Normal in Akitas
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24
Q

What is Red Cell distribution Width?

A

A numeric representation of the variability in RBC size, more sensitive than MCV

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25
Q

How is red blood cell colour assessed?

A

MCH and MCHC (mean cell haemoglobin/concentration in cells)

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26
Q

What is MCHC?

A
  • g/L = Hb (g/L)/PCV (L/L)
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27
Q

What is MCH?

A
  • pg = Hb (g/L)/RBC (10^12/L)
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28
Q

Compare the use of MCHC and MCH

A

MCHC more useful than MCH since cell size is taken into account

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29
Q

Explain what is meant by normochromic and hypochromic red blood cells

A
  • Normo: normal MCHC, normal Hb content

- Hypo: low MCHC, low Hb content

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30
Q

What may cause a raised MCHC?

A
  • Not physiologically possible
  • Almost always due to sample or in vivo haemolysis
  • May be artifactual in lipaemic samples
  • or Heinz bodies
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31
Q

What is the haemoglobin distribution width?

A

Hb equivalent of RDW, numeric equivalent to seeing polychromasia on slide

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32
Q

What is indicated by normochromic, microcytic red blood cells?

A

Most likely analytic error, miscounting paltelets

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33
Q

What is indicated by microcytic, hypochromic cells?

A

Fe deficiency or PS shunts

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34
Q

What is indicated by macrocytic, hypochromic cells?

A

Regenerative anaemia (or cell swelling in sample transport)

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35
Q

What is indicated by normocytic, normochromic red blood cells?

A

If anaemic, often inflammation/chronic illness

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36
Q

Name the different morphological appearances of red blood cells

A
  • Codocytes
  • Acanthocytes
  • Spherocytes
  • Schistocytes
  • Burr cells/crenation
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37
Q

Define poikilocytosis

A

Alterations in cell’s shape, may be due to abnormal erythropoiesis or specific organ dysfunction

38
Q

describe the appearance of codocytes

A
  • Aka target cells
  • Central haemoblobinised area surrounded by an area of pallor, periphery of cell contains band of haemoglobin
  • Lack normal biconcave cross section due to folding of cell membrane
39
Q

What may cause the production of codocytes?

A
  • Iron deficiency anaemia
  • Liver disease with cholestasis
  • After splenectomy in dogs
40
Q

What are leptocytes?

A

Thin, empty RBCs

41
Q

Describe the appearance of acanthocytes

A
  • Aka spur cells

- Rounded projections of variable diameter and length, unevenly distributed

42
Q

What causes the formation of acanthocytes?

A
  • Increase in membrane cholesterol or associated with RBC fragmentation
  • See in diffuse liver disease
  • Splenic haemangioma
  • Haemangiosarcoma
  • Portosystemic shunts
  • High cholesterol diet
43
Q

Describe the appearance of spherocytes

A
  • Small, densely staining spherical RBCs lacking central pallor
  • Small portions of cell membrane may have been phagocytosed by mononuclear phagocytes residual cellular tissue resume that smallest shape possible i.e. sphere
44
Q

What causes the formation of spherocytes?

A
  • Immune mediated haemolytic anaemia in dogs
  • Presence of surface bound antibodies or complement
  • Present in animals that have had transfusions
45
Q

Describe the appearance of schistocytes

A

Irregular, fragmented erythrocytes due to mechanical trauma to circulating erythrocytes

46
Q

What causes the formation of schistocytes?

A
  • DIC, other angiopathies
  • Immune mediated anaemia
  • Thrombosis
  • Splenic haemagiosarcoma
  • Hypersplenis
  • Glomerulonephritis
  • Congestive heart failure
  • Valvular heart disease
  • Doxorubicin toxicosis and myelofibrosis
47
Q

Describe the appearance of crenation in ertyrhocytes aka burr cells

A

RBCs with spiked projections of uniform length

- aka echinocytes

48
Q

What may cause the formation of burr cells?

A

MOSTLY artifactual e.g sampling into EDTA tube with incorrect ratio blood to EDTA

  • Some normal in ruminants
  • Rarely snake envenomation
  • Occasionally dehydration
49
Q

Describe rouleaux formation

A
  • Clustering of RBCs in standing blood
  • Normal in horses
  • Increased stickiness of plasma with increased globulin content
50
Q

What does rouleaux formation indicate in small animals?

A

Inflammation

51
Q

How can rouleauxz formation and agglutination be distinguished from one another?

A
  • To confirm agglutination, mix 1 drop blood with 1 drop saline
  • Agglutintion persists due to antibodies sticking RBCs together, rouleaux will disperse
52
Q

What are the pathological causes of agglutination?

A

Immune mediated haemolytic anaemia, mismatched blood transfusions (agglutinate due to presence of antibodies sticking cells together)

53
Q

Describe the appearance of Heinz bodies

A

Irregular shaped, refractile inclusions consisting of oxidative denatured haemoglobin

54
Q

What may cause the formation of Heinz bodies?

A
  • Up to 10% of RBCs in normal cats
  • Paracetamol and onion toxicity (+ other oxidative compounds)
  • Diabetes mellitus
  • Lymphoma
  • Hyperthyroidism
55
Q

What stain should be used to confirm the presence of Heinz bodies?

A

New methylene blue (NMB)

56
Q

What causes basophilic stippling of RBCs in dogs, cats and ruminants?

A
  • In vivo aggregation of ribosomes into small basophilic granules, caused by low levels of pyrimidine 5’-nucleotidase (P5N) enzyme that catabolises ribosomes
  • In cats and dogs: intensely regenerative anaemia, lead poisoning
  • Normal in immature erythrocytes in ruminants
57
Q

Describe the appearance of basophilic stippling

A
  • Multiple, small, dark blue, punctate aggregates in RBCs
58
Q

What are metarubricytes and what are they also known as?

A
  • Nucleated erythrocytes

- aka nRBCs, normoblasts

59
Q

What are the potential causes of the formation of metarubricytes?

A
  • Regenerative anaemia
  • Production of RBCs outside of the bone
  • Non-functioning spleen
  • Marrow damage
60
Q

What causes the formation of nucleated erythrocytes in the absence of polychromasia in cats?

A

Myelodysplasa or myeloproliferative disease

61
Q

What is the significance of nucleated RBCs with regards to laboratory analysers?

A

May count as white cells, need to check manually on slide if these are present

62
Q

What are Howell-Jolly bodies?

A

refractile, singlye blueish bodies in RBCs of variable size, representing nuclear remnants

63
Q

What may cause the formation of Howell-Jolly bodies?

A
  • Regenerative anaemia
  • Splenectomy
  • Suppressed splenic function
  • Higher percentage normally seen in cats
64
Q

Describe the appearance of babesiosis on blood smears

A
  • Visible intracellular as eosinophilic blobs

- Can cause haemolytic anaemia, systemic inflammatory syndrome, multiple organ dysfunction syndrome

65
Q

Describe the appearance of Mycoplasma haemofelis on blood smears

A

Highly pleomorphic, apperaing as chains, discs or rods on surface or embedded into RBC membranes

66
Q

Briefly outline the clinical signs of Mycoplasma haemofelis (and give the alternative name)

A
  • Haemobartonella felis

- Regenerative anaemia, pyrexia, malaise

67
Q

What is the rule of 3 and how can errors be identified on haematology?

A
  • Look at MCHC
  • HCT% approx = Hb (g/dL) x3 (+/-3%)
  • If this is not true for the sample, the something has been mismeasured
  • When PCV, RBCC, Hb increase/decrease usually do this in line with each other, if discordant is abnormal, need to find out why = rule of three
68
Q

What may lead to an incorrect PCV?

A
  • RBCs miscounted e.g. mistaken for platelets

- MCH misleading (cell shrinkage or swelling as consequence of handling or dehydration_

69
Q

What artefacts commonly occur regarding MCV?

A
  • Swelling of transport
  • Mis-identification (pairs, triplets cross over with large platelets)
  • Cell shrinkage or expansion in sample e.g. hyperosmolar
70
Q

How is PCV calculated?

A

MCV x RBCC

71
Q

What needs to be considered when evaluating the erythron?

A
  • Is there inadequate, adequate or excessive red cell mass to deliver oxygen to tissues?
  • Evidence of anaemia? Regeneration?
  • Evidence of polycythaemia? Relative or absolute?
72
Q

List the main classifications of anaemia

A
  • Normocytic normochromic
  • Macrocytic hypochromic
  • Microcytic hypochromic
73
Q

What is polycythaemia?

A

Increase in PCV, Hb concentration and RBC count

74
Q

Compare polycythaemia in humans and in dogs and cats

A
  • In humans, usually implies increased number of several haemopoetic cell lines
  • In dogs and cats, usually have normal neutrophil and platelet counts with polycythaemia vera
75
Q

What is meant by relative polycythaemia?

A

Apparent increase in RBC due to decrease in fluid circulation, also often increased total protein and albumin

76
Q

What are the causes of relative polycythaemia?

A
  • Dehydration: water or cellular fluid loss e.g. V/D, PU, extensive burns, adipsia, water deprivation
  • Splenic contraction due to adrenaline secretion e.g. exercise, fear, excitement, severe pain, stress
77
Q

What is absolute polycythaemia and name the types

A

True increase in RBC mass due to increased RBC production/release

  • Primary polycythaemia vera
  • Secondary polycythaemia
78
Q

Describe primary polycythaemia vera

A
  • Rare myeloproliferaive disorder, abnormal response of RBC precursors, normal EPO levels
79
Q

Describe secondary polycythaemia

A
  • Chronic tissue hypoxia of renal tissues due to heart/lung disease
  • High altitude
  • Thrombosis
  • constriction of renal vessels
  • Renal tumour or cysts increasing intracapsular pressure preventing inflow of blood
  • Increased EPO release by kidneys
80
Q

What aspects of the erythron are assessed in the investigation of disease of the erythroid system?

A
  • Red cell mass (PCV, RBCC, Hb)
  • Evidence for effectie erythropoiesis (size, colour, reticulocyte count)
  • Red cell size and variation (MCV, RDW)
  • Red cell hemoglobinisation (colour, MCHC)
  • Red cell shape and inclusions (smear)
  • i.e. size, shape, colour, distribution, structure
81
Q

What are eccentrocytes?

A

RBCs with ragged appearance, poorly haemoglobinised fringe of cytoplasm along one side of cell

82
Q

What causes the formation of eccentrocytes?

A
  • Excess oxidant stress to erythrocytes
  • Inherited glucose-6-phosphate deficiency increasing susceptibility to oxidant induced erythrocyte injury e.g. onion poisoning
83
Q

Give examples of congenital portosystemic shunts

A
  • Persistent sinus venous connection
  • Direct portal vein connection
  • Connections to caudal vena cava or azygous vein
84
Q

What causes the formation of acquired portosystemic shunts? Describe the structure

A

Portal hypertension typically

- Typically multiple extra hepatic shunts that connect the portal system to the caudal vena cava

85
Q

Which animals are predisposed to congenital portosystemic shunts?

A
  • Yorkies
  • Miniature schnauzers
  • Irish Wolfhounds
  • Old english sheepdogs
  • Cairn terriers
  • Mixed breed cats
86
Q

Describe some diagnostic features for portosystemic shunts

A
  • Central nervous system signs
  • Poor growth
  • Non-specific GI signs
  • crytporchidism in dogs and cats
  • PUPD in dogs
  • Cats: Heart murmurs, seizures, ptyalism, copper iris colour in cats
87
Q

Compare the types of portosystemic shunts found in small and large breed dogs

A
  • Large: usually intrahepatic

- Small; usually extrahepatic

88
Q 
What would the following  signs be indicative of in a dog?
Mild non-regenerative anaemia with microcytosis and poikilocytosis
Mildly elevated ALT and ALP
Low BUN
Hypocholesterolaemia
Hypoglycaemia
Hypoalbuminaemia and globulinaemia
Seizures, V/D, PUPD, poor growth
A

Portosystemic shunt

89
Q

What is the reticulocyte production index used for?

A

Corrects reticulocyte count for PCV and indicates if level of regeneration is appropriate

90
Q

What is CRP?

A

Corrected reticulocyte percentage

LCB2 (14 decks)

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