Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y2 MCD Haem Fwong > Anaemia and Polycythaemia > Flashcards

Anaemia and Polycythaemia Flashcards

1
Q

What is anaemia?

A

A reduction in the amount of haemoglobin in a given volume of blood below what would be expected in comparison with a healthy subject of the same age and gender

RBC and Hct are usually also reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Other than a reduction in the absolute amount of haemoglobin in the blood stream, what else could cause anaemia?

A

An increase in the plasma volume can decrease the haemoglobin concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why would this type of anaemia only be transient in a healthy individual?

A

The excess fluid would be excreted in a healthy individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Broadly speaking, state four mechanisms of anaemia.

A

Reduced production of red blood cells/haemoglobin in the bone marrow
Loss of blood from the body (haemorrhage or eg into the stools)
Reduced survival of red blood cells (haemolytic)
Pooling of red blood cells in a very large spleen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

For each type of anaemia(microcytic, normocytic and macrocytic), state whether they are usually hypochromic, normochromic or hyperchromic.

A

Microcytic – hypochromic as both are usually caused by defect in Hb synthesis
Normocytic – normochromic
Macrocytic - normochromic, macrocytosis is usually caused by other defects rather than Hb synthesis so Hb conc would be normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

State the common causes of microcytic anaemia.

A

In general, it is caused by problems in Hb synthesis.
Problem with Haem synthesis
 Iron deficiency
 Anaemia of chronic disease: anaemia is associated to some chronic inflammatory diseases like rheumatoid arthritis
Problem with globin synthesis
 Alpha thalassemia (alpha chain defect)
 Beta thalassemia (beta chain defect)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What mechanism usually causes macrocytic anaemia?

A

Macrocytic anaemias usually result from abnormal haemopoiesis so that the red cell precursors continue to synthesize haemoglobin and other cellular proteins but fail to divide normally
As a result, the red cells end up larger than normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is megaloblastic erythropoiesis? Describe the appearance of a megaloblast.

A

Megaloblastic erythropoiesis is a mechanism for MACROCYTIC ANAEMIA.
A megaloblast is an abnormal bone marrow erythroblast

The nucleus is delayed but the rest of the cell continues to grow. Cannot produce DNA quickly enough to divide at the right time and thus grow too large before division

They are large and show nucleo-cytoplasmic dissociation (nucleus more primitive compared to the rest of the cell)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is an alternative mechanism of macrocytosis?

A

Reticulocyte mechanism.

NB two mechanisms for macrocytic anaemia:

  1. reticulocyte
  2. megaloblastic

You can get premature release of cells from the bone marrow (reticulocytes)
Reticulocytes are about 20% larger than mature red cells so reticulocytosis would increase the MCV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

State the two most common causes of megaloblastic anaemia.

A

B12 deficiency

Folate deficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

State some causes for the 2 mechanisms of macrocytic anaemia:

  1. megaloblastic mechanism
  2. Reticulocyte mechanism
A 
Megaloblastic:
B12 deficiency 
Folate deficiency 
Drugs that interfere with DNA synthesis (e.g. chemotherapy) 
Liver disease  
Ethanol toxicity

Haemolytic:
Recent major blood loss with adequate iron stores (reticulocytes increased). Bone marrow tries to spit out reticulocytes to compensate for the blood loss

Haemolytic anaemia (reticulocytes increased). Breakdown of RBC causing bone marrow to spit out reticulocyte which are bigger than normal RBC, hence causing macrocytic anaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

State three mechanisms of normocytic normochromic anaemia.

A

Recent blood loss
Failure to produce red blood cells
Pooling of red blood cells in the spleen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

State five causes of normocytic normochromic anaemia.

A
  1. Mechanism=Recent blood loss, caused by eg:
    Peptic ulcer
    Oesophageal varices
    Trauma

2.Mechanism=Failure of production of red blood cells, caused by:
 Early stages of iron deficiency and Anaemia of CD
 Renal failure (drop in EPO)
 Bone marrow failure (reduced no of stem cells or bone marrow suppression by cancer drugs)
 Bone marrow infiltration by eg cancer cells

  1. Mechanism= Pooling of RBC in spleen, caused by PORTAL CIRRHOSIS (cirrhosis of liver)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define haemolytic anaemia.

A

Anaemia resulting from shortened survival of red blood cells in the circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

State two different classifications of haemolytic anaemia.

A

INHERITED OR ACQUIRED
OR
INTRAVASCULAR OR EXTRAVASCULAR

Haemolysis can be inherited (resulting from abnormalities of the cell membrane, haemoglobin or the enzymes in the red blood cell)

It can be acquired usually resulting from extrinsic factors such as micro-organisms, chemicals or drugs

Haemolytic anaemia can also be described as intravascular if there is very acute damage to the red cell
It can also be classified as extravascular when the spleen removes defective red cells too quickly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

State some inherited abnormalities that can cause haemolytic anaemia.

A 
Abnormal red cell membrane eg hereditary spherocytosis
Abnormal haemoglobin  (Sickle cell)
Defect in the glycolytic pathway  (pyruvate kinase deficiency)
Defect in the enzymes of the pentose shuttle (eg G6PD deficiency)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

State some acquired abnormalities that cause haemolytic anaemia.

A

Damage to the red cell membrane
Damage to the whole red cell
Oxidant exposure

18
Q

Explain how G6PD Deficiency can cause haemolytic anaemia.

A

slide 27
G6PD is part of the pentose phosphate pathway, this pathway produces a lot of NADPH which helps to REDUCE OXIDATIVE STRESS. Without this pathway, cell would be more prone to oxidative stress.

Because of the oxygen-carrying role of red blood cells, they are at constant risk of oxidant damage

So people with G6PD deficiency are at risk of haemolytic anaemia via oxidative stress

19
Q

When would you suspect haemolytic anaemia?

A
  1. Otherwise unexplained anaemia that is normochromic and usually either normocytic or macrocytic
  2. Evidence of morphologically abnormal red cells
  3. Evidence of increased red blood cell turnover (increased bilirubin and lactate dehydrogenase, LDH is released when cells are destroyed)
  4. Evidence of increased bone marrow activity
20
Q

What does the presence of fragments in the blood film suggest?

A

This suggests that red blood cells are being broken down within the circulation (in the small circulation)

21
Q

What condition causes breakdown of red blood cells in small blood vessels?

A

Microangiopathic haemolytic anaemia

Caused by overactive coagulation system, leading to fibrin mesh formation, these are protein networks that CUT RBC into schistocytes.

22
Q

State some important signs of haemolytic anaemia.

A

Jaundice – because of the increased break down of red blood cells there is an increase in bilirubin
The increase in bilirubin can also increase the risk of getting gallstones

23
Q

State examples of inherited diseases causing haemolytic anaemia that have defects at the following sites:

a. Membrane
b. Haemoglobin
c. Glycolytic Pathway
d. Pentose Shunt

A 
a. Membrane 
Hereditary spherocytosis 
b. Haemoglobin 
Sickle cell anaemia 
c. Glycolytic Pathway 
Pyruvate kinase deficiency
d. Pentose Shunt 
G6PD deficiency
24
Q

State examples of acquires disease causing haemolytic anaemia that have defects at the following sites:

a. Membrane - immune
b. Whole red cell - mechanical
c. Whole red cell - oxidant
d. Whole red cell - microbiological

A 
a. Membrane – immune 
Autoimmune haemolytic anaemia
b. Whole red cell –mechanical 
Microangiopathic haemolytic anaemia
c. Whole red cell – oxidant 
Drugs and chemicals
d. Whole red cell – microbiological 
Malaria
25
Q

What is hereditary spherocytosis?

A

This is haemolytic anaemia or chronic compensated haemolysis resulting from an intrinsic inherited defect of the red cell membrane
After entering the circulation, the cells lose membrane in the spleen and become spherocytic

26
Q

What are the features of red cells in hereditary spherocytosis?

A

They are LARGE and ROUND and have an increased MCHC

27
Q

How does the bone marrow respond to the increased extravascular haemolysis in hereditary spherocytosis?

A

It increases the output of red cells leading to polychromasia and reticulocytosis

28
Q

What is an effective treatment for hereditary spherocytosis?

A

Splenectomy

29
Q

Why is a good diet important in patients with hereditary spherocytosis?

A

They have increased bone marrow activity and erythropoiesis so they need a supply of B12, folate and iron to keep producing red blood cells

30
Q

Describe the pattern of inheritance of G6PD deficiency.

A

X linked recessive

31
Q

What can G6PD deficiency cause?

A

Intermittent, severe intravascular haemolysis as a result of infection or exposure to an exogenous oxidant

32
Q

What tends to appear in blood films during these episodes of severe intravascular haemolysis?

A

Irregularly contracted cells

33
Q

What happens to the haemoglobin during these episodes?

A

It becomes denatured and forms round inclusions called Heinz bodies
NOTE: you can get more than one Heinz body per cell unlike Howell-Jolly bodies

34
Q

What causes autoimmune haemolytic anaemia?

A

Results from the production of antibodies against red cell antigens
This is very sudden and dramatic

35
Q

Describe how autoimmune haemolytic anaemia can lead to spherocytosis.

A

The immunoglobulin bound to the red cell is recognised (Fc part) by splenic macrophages, which remove parts of the cell membrane leading to spherocytosis

36
Q

State two causes of spherocytosis.

A

Hereditary spherocytosis

Autoimmune haemolytic anaemia

37
Q

Describe the diagnosis of autoimmune haemolytic anaemia.

A

Finding spherocytes
Increased reticulocyte count
Detecting immunoglobulin±complement on the red cell surface
Detecting autoantibodies to red cell antigens or other autoantibodies in the plasma
slide 56

38
Q

What is the treatment for autoimmune haemolytic anaemia?

A

Corticosteroids or other immunosuppressive agents Splenectomy in severe cases

39
Q

Which red blood cell parameters are increased in polycythaemia?

A

RBC
Hct
Hb

40
Q

What is the term given to a condition where these parameters are increased but the absolute amount of haemoglobin is not increased?

A

Pseudopolycythaemia (or apparent polycythaemia)

This is due to a decrease in plasma volume

41
Q

State some causes of polycythaemia.

A

Blood doping
Elevation of EPO when at altitude
Tumour (renal or other tumour that can secrete high amounts of EPO)
Abnormal function of bone marrow – it can result from inappropriately increased erythropoiesis that is independent of EPO, this is an intrinsic bone marrow disorder called polycythaemia vera
It is a chronic myeloproliferative neoplasm

42
Q

What are the consequences of polycythaemia?

A

Hyperviscosity of the blood

This can lead to vascular obstruction

Y2 MCD Haem Fwong (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions