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Anaemia Flashcards

1
Q

What is anaemia in terms of haemoglobin levels and what does this mean?

A

Haemoglobin level is lower than normal as a result of insufficient Hb or RBC, this means there is a reduction in the bloods ability to oxygenate tissues - hypoxia

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2
Q

What is MCV, MCH, MCHC?

A 
MCV = mean cell volume
MCH = mean cell haemoglobin content
MCHC = mean cell haemoglobin concentration
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3
Q

How is anaemia classified based on RBC size?

A
  1. Microcytic - RBCs are hypochromic - low MCV and MCH. caused by Fe deficiency
  2. Nromocytic - RBCs are normochromic - normal Mcv and MCH. Caused by acute blood loss
  3. Microcytic - RBCs are hyperchromic - high MCV. Caused by B12 and folate deficiency
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4
Q

How is anaemia classified based on mode of development? - just the names

A
  1. Excess loss
  2. Failure of production
  3. Excess destruction
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5
Q

How does excess blood loss cause anaemia?

A

Caused by acute haemorrhage (more than 1 litre of blood lost) or chronic haemorrhage - present as Fe deficiency.
RBCs are normochromic

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6
Q

How does failure of production cause anaemia?

A

Causes deficiency anaemia - defieicny of iron, B12 or folate.

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7
Q

What are haemantinics?

A

Molecules that make blood cells - iron, B12, Folate

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8
Q

How is iron present in the body?

A

75% in Hb, 20% in ferritin, 5% in myoglobin, 0.1% in transferrin

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9
Q

What are the daily sources of iron and how is it lost?

A

Non-haem iron (Fe3+) - from plant food - it is not easily absorbed by the body
Haem iron (Fe2+) - from myoglobin and Hb in meat, rapidly absorbed.
Mainly lost through sloughing of epithelial cells at skin and mucosal cells.

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10
Q

How is iron absorbed into the blood?

A

Fe2+ can be easily absorbed by Fe3+ needs to be converted to Fe2+ through a reduction reaction.
Vitamin C and citric acid are reducing agents so promote the absorption of iron.
Phytates, phosphates and tannins bind to Fe and inhibit absorption so they are inhibitors.

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11
Q

What can cause the malabsorption of Fe?

A

High phytate diet

Low vitamin C diet

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12
Q

How can iron be supplemented?

A

Oral haem iron - but this can stain teeth so sodium iron is used instead.
Iron supplements can cause tooth erosion - including chewable vitamin c

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13
Q

What are the sources of vitamin B12 and folate?

A

B12 from animal produce (meat and dairy). Humans have a low daily intake and it can be stored for several years.
Folate from liver and vegetables. Humans have a high daily intake and it is only stored for a few months.

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14
Q

What effects does B12 or folate deficiency have on cells?

A

B12 and folate are essential for DNA synthesis, so if deficient there will be ineffective DNA synthesis. Nuclear saturation is delayed but the cells continue to accumulate in the cytoplasm. So all forms of the myeloid line precursors increase in the blood. This causes megaloblastic anaemia.

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15
Q

How is B12 and folate essential for DNA synthesis?

A

In the blood folate is converted into dihydrofolate then to tetrahydrofolate, methylene FH4 and then Methyl FH4. Methyl FH4 can then be converted back to tetrahydrofolate using vitamin B12 as a cofactor. More trtrahydrofolate so more methylene, methylene is then converted back to dihydrofolate using the conversion of dUMP to dTMP which makes DNA.
If B12 is deficient then folate will be stored as methyl and will also be deficient.

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16
Q

What is megaloblastic anaemia?

A

Slowed DNA synthesis as a result of prolonged cycling.

Delayed maturation of nucleus and delayed division leading to macrocytic cells (large and misshapen)

17
Q

What 2 main problems are caused by B12 deficiency, and how is it caused?

A

Lack of coenzyme fro FA breakdown, so odd number of FA in the cells which leads to neurological symptoms.
Secondary folate deficiency as it causes folate to be trapped as methyl, nucleotide synthesis will decrease.
Caused by diet, GIT disease (pernicious anaemia) or GIT surgery. Large stores for several years so takes 2 years to develop.

18
Q

How is B12 absorbed from the diet?

A

Into the stomach, the parietal cells lining the stomach release intrinsic clotting factor (IF). The IFs bind to B12 and move through the GI tract.
In the intestine IF B12 complex bind to mucosal cells and B12 is released into the bloodstream.

19
Q

What is pernicious anaemia?

A

AN increase in the production of antibodies against parietal cells, increasing atrophy (death) so less IFs released.
Or
Antibodies made against the binding sites on the IFs (binding site for B12 and binding site for mucosal cells), so B12 cannot be absorbed.

20
Q

What are the signs of pernicious anaemia?

A 
Depaptilation of the tongue
Ulcers
Blood sample shows large MCV
Blood film shows macrocytic cells
Serum B12 is low
Auto immune profile shows a high level of gastric parietal cell antibodies.
21
Q

What is Schillings test?

A

Test to determine if an individual has pernicious anaemia.
Patient is given a small dose of radioactive B12, followed by a large dose of normal B12 (to saturate the IFs - no radioactive in the blood).
Urine is collected.
If more than 15% B12 =normal
Less than 15% B12 suggests malabsorption
Test is then repeated but with B12 and IFs. If more than 15% B12 = pernicious anaemia, if less than 15% suggest ill disease.

22
Q

How is folate deficiency caused and how is it diagnosed?

A

Caused by a poor diet, increase in requirement (pregnancy), malabsorption.
Diagnosed by taking serum folate and RBC folate - will be below normal
Treated with folic acid

23
Q

What is aplastic anaemia and what are the signs?

A

Bone marrow not functioning.
RBC = normochromic
WBC = low = leucopenia
Platelets = low

24
Q

How is excess loss anaemia classified by RBC size?

A

Normochromic

25
Q

How is megaloblastic anaemia classified by RBC size?

A

Macrocytic - hyper chromic

26
Q

What is the MCV like of someone with pernicious anaemia?

A

High

27
Q

How is pernicious anaemia classified by RBC size?

A

Macrocytic

28
Q

How is aplastic anaemia classified by RBC size?

A

Normochromic

Blood (7 decks)

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