Approach to anaemia 1 Flashcards

1
Q

What is anaemia defined as?

A

Reduction of either:

  1. PCV or haematocrit
  2. RBC count
  3. Haemoglobin
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2
Q

Is anaemia associated with underlying disease?

A

Always - anaemia is a clinical sign, not a disease

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3
Q

Is acute or chronic anaemia worse?

A

Acute

Chronically anaemic animals can compensate

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4
Q

What are examples of responses to anaemia?

A

Increased RBC 2,3 DPG
Alterations in tissue perfusion
Alterations in behaviour
Different oxygen affinity behaviour (cats only)

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5
Q

What does 2,3 DPG do?

A

Lowers affinity of haemoglobin for oxygen

Facilitates release of oxygen

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6
Q

How does increased RBC 2,3 DPG help in response to anaemia?

A

Increased RBC 2,3 DPG causes lower O2-haemaglobin affinity

Better delivery of oxygen to tissues

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7
Q

What can only cats do in response to anaemia?

A

Different haemoglobins - respond over range of oxygena conditions

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8
Q

Tissue perfusion alters in response to anaemia. What hormonal effect does this have?

A

Lack of perfusion causes increased erythropoietin

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9
Q

Where is erythropoietin produced? What does it do?

A

Kidneys

Stimulates RBC production

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10
Q

Give an example of a behaviour associated with anaemia, particularly in cats

A

Pica

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11
Q

Give examples of what you may see on a physical exam of an anaemic animal

A
Jaundice 
Pallor
Weakness
Prolonged CRT
Tachycardia etc
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12
Q

How can anaemia be classified (3 descriptions)

A

Degree of severity
Erythrocyte indexes
Regenerative response

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13
Q

What are the 3 degrees of severity for anaemia?

A

Mild, moderate, severe

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14
Q

What are examples of erythrocytes indexes when describing anaemia?

A

Microcytic, normocytic or microcytic

Hypochromic or normochroic

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15
Q

What are the 3 main causes of anaemia?

A

Inadequate production by bone marrow
Increased destruction of RBCs
Haemorrhage

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16
Q

What types of anaemia can be caused by inadequate production by bone marrow - severity, RBC index and regeneration?

A

Mild to severe
Normocytic, normochromic
Non-regenerative

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17
Q

What type of anaemia can be caused by increased destruction of RBCs - regeneration, RBC index and immune mediated?

A

Regenerative
Macrocytic hypo chromic or normocytic normochromic
Immune mediated or non-immune mediated

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18
Q

Does haemorrhage cause proportional or disproportional loss of blood components? Does it cause regenerative or non-regenerative anaemia?

A

Proportional

Regenerative usually

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19
Q

How does the body recover hypovolaemia after haemorrhage?

A

Interstitial fluid moves into vascular space (within a few hours)

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20
Q

A few hours after haemorrhage, how does the total protein differ? What other haematological abnormalities are present?

A

Low total protein - blood diluted by ISF

Decreased PCV, haematocrit and erythrocyte mass

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21
Q

How can acute blood loss present clinically?

A

Hypovolaemic shock - pallor, tachycardia, weak pulse, cold extremities, increased lactate

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22
Q

How long does blood need to be lost to define it as chronic?

A

More than 2 weeks

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23
Q

How long does chronic blood loss need to continue to develop iron deficiency anaemia in an adult?

A

1 month - abundant iron supply

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24
Q

Does acute or chronic blood loss cause IDA?

A

Chronic

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25
Q

Is chronic blood loss regenerative or non-regenerative?

A

Can be either

Eventually lack of iron slows down erythropoiesis

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26
Q

What 2 things on a blood smear indicates regenerative anaemia?

A

Reticulocytosis

Polychromasia

27
Q

What stain is used for reticulocytes?

A

Methylene bue

28
Q

Is reticuocytosis or polychromasia more accurate to diagnose regenerative anaemia?

A

Reticulocytosis

Rely on absolute count not % - do manually as can be mistaken as WBC

29
Q

When do reticulocytes become present from the onset of regenerative anaemia? When are they at peak levels?

A

Start 2-3 days after onset

Peak at 4-7 days

30
Q

What can cause iron deficiency anaemia?

A

Chronic haemorrhage
Dietary deficiency
Congenital haemostatic defects
Parasitic infestations

31
Q

What is the most common cause of iron deficiency anaemia? What can cause this?

A

GI haemorrhage

NSAIDs, ulceration, neoplasia, parasites

32
Q

How does iron deficiency affect red blood cells size and colour?

A

Causes hypochromic and microcytic RBCs

33
Q

How does iron deficiency cause microcytic and hypo chromic RBCs?

A

Production of haemoglobin defective with iron deficiency

Extra divisions of RBC precursors cause smaller and hypo chromic RBCs

34
Q

Give examples of drugs that can be used to treat chronic GI haemorrhage

A

Sucralfate
Ranitidine
Omeprazole

35
Q

Why should antacids be administered several hours apart from each other?

A

Interfere with iron absorption

36
Q

How is IDA treated?

A

Treat underlying cause
Iron supplementation
(RBC transfusion)

37
Q

What can be given for iron supplementation with IDA?

A

Oral ferrous sulphate

Intramuscular iron dextran

38
Q

Why should precautions be taken when administering iron dextran IM?

A

Painful

Can cause anaphylaxis

39
Q

Can IDA be caused by a dietary deficiency?

A

Yes - if vegan diet
Particularly puppies and kittens
Supplement and transfer diet

40
Q

What are the 2 causes of immune mediated RBC destruction?

A

Immune mediated haemolytic anaemia

Neonatal isoerythrolysis

41
Q

Briefly describe the pathogenesis of IMHA?

A

Production of antibodies against RBCs

RBCs removed by macrophages

42
Q

In which organs does extravascular haemolysis take place?

A

Spleen
Liver
Bone marrow

43
Q

Extravascular haemolysis causes the release of what products?

A

Unconugated bilirubin
Aminoacids
Globin
Iron

44
Q

What affect does extravascular haemolysis have on the spleen and liver?

A

Enlargement - splenomegaly and hepatomegaly

45
Q

What are the symptoms of extravascular haemolysis?

A

If liver capacity overwhelmed - hyperbilirubinaemia, bilirbuinurea, jaundice
Collapse etc

46
Q

What colour is urine depending on if haemolysis is intra or extravascular?

A
Intravascular = red urine 
Extravascular = yellow urine
47
Q

What are the symptoms of intravascular haemolysis?

A

Haemoglobinaemia

Haemoglobinuria

48
Q

How can intravascular haemolysis cause renal compromise?

A

Free haemoglobin damages tubular epithelium

49
Q

What on a blood smear is strongly supportive of IMHA?

A

Spherocytes

Look smaller but actually just spherical shape

50
Q

How can spherocytes be differentiated from microcytes?

A

Microcytes have central pallor, spherocytes do not

51
Q

How does IMHA cause spherocytes?

A

Macrophages pit membrane of RBC

Decreased RBC surface causes loss of shape

52
Q

Is IMHA primary or secondary to infection or neoplasia?

A

Either

53
Q

Where on a blood smear should you look for spherocytes?

A

Monocyte layer

54
Q

How can immune mediated haemolytic anaemia be diagnosed by blood smear?

A

Regenerative anaemia WITH

Marked spherocytosis and or agglutination

55
Q

Why does IMHA cause auto agglutination?

A

Antierythrocyte antibodies high - causes agglutination

Can be macro (visible grossly) or micro

56
Q

IMHA can lead to cell lysis or cell ghosts - how?

A

RBC directly damaged by complement

57
Q

Why shouldn’t immunosuppressive drugs be given without finding cause of IMHA?

A

May be due to infection, cause animal to get sicker

58
Q

How can IMHA be diagnosed?

A

Clinical signs
Haematology
Coomb’s test

59
Q

What is Coombs’ test used for? When might it not work?

A

For autoimmune haemolyticc anaemia - detects anti RBC antibodies
Cannot be done if agglutination already present

60
Q

What is the Alvedia anti globulin test used for?

A

IMHA

Immunochromatography done in house

61
Q

What can cause non-immune mediated increased destruction?

A

Oxidative damage
Intraerthrocytic parasites
Mechanical damage - angiopathic anaemia
Bacteria/viruses

62
Q

What can cause oxidative damage?

A

Onion, garlic
Red maple (horses)
Paracetamol (cats)
Copper (sheep)

63
Q

Give 2 examples of intra-erythrocytic parasites

A

Babes

Mycoplasma haemofelis