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MEH > intro to anaemia > Flashcards

intro to anaemia Flashcards

1
Q

define anaemia

A

a haemoglobin conc lower than normal range

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2
Q

is anaemia itself a diagnosis

A

no but a manifestation of an underlying disease

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3
Q

what are the main symptoms of anaemia

A
  • shortness of breath
  • palpitations
  • headaches
  • claudication (muscle pain due lack of O2)
  • angina
  • weakness and lethargy
  • confusion
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4
Q

what are the main signs of anaemia

A
  • pallor
  • tachycardia
  • systolic flow murmur
  • tachypnoea
  • hypotension
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5
Q

what are specific clinical signs associated with the cause of anaemia

A

IRON DEF:
- koilonychia (spoon nails)
- angular stomatitis (inflam corners mouth)

VIT B12 DEF:
-glossitis (imflam tongue)

THALASSAEMIA:
- abnormal facial development

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6
Q

what are the three causes of anaemia in bone marrow

A
  • reduced or dysfunctional erythopoiesis
  • abnormal haem synthesis
  • abnormal globin chain synthesis
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7
Q

what are the four causes of anaemia in peripheral blood cells

A

abnormal structure
mechanical damage
abnormal metabolism
excessive bleeding

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8
Q

what are the causes for anaemia in removal or RBC

A

increased removal by reticuloendothelial system

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9
Q

how can anaemia develop from reduced erythropoiesis

A
  • lack of response in haemostatic loop so in chronic kidney disease kidney stops making erythropoietin
  • marrow does not respond to EPO
  • marrow infiltrated by cancer or fibrous tissue so less haemopoietic cells
  • iron not made available for RBC
  • myelodysplastic syndrome abnormal stem cells in marrow
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10
Q

how can anaemia develop from defects in Hb synthesis

A
  • mutations in genes for globin –> thalassemia
  • defects in haem synthesis –> sideroblastic anaemia
  • insufficient iron in diet to make haem
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11
Q

how can anaemia develop from abnormal structure (inherited)

A
  • mutations in genes coding for proteins involved in interactions between plasma mem and cytoskeleton
  • less flexible and more easily damaged
  • break up in circulation and removed more quickly by RES
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12
Q

how can anaemia develop from mechanical damaged (acquired)

A
  • damaged caused by mechanical valves
    -cells snagging on fibrin strands in small vessels causing clots
  • heart damage from severe burns
    osmotic damage (drowning)
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13
Q

what are the fragments called when RBC go under mechanical damage

A

schistocytes

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14
Q

why might anaemia develop from defects in cell metabolism

A
  • G6PDH deficiency:
    more ox stress to RBC –> Heinz bodies and cleared by RES
  • pyruvate kinase deficiency:
    RBC no mito so deficient in ATP without pyruvate kinase so undergo haemolysis
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15
Q

why might anaemia develop from excessive bleeding

A
  • acute blood loss (injury, surgery, childbirth, ruptured vessel)
  • chronic bleeding (menstruation, nosebleeds, haemorrhoids, gastro bleeding in stool, kidney or bladder tumours)
  • chronic NSAID usage (aspirin, ibuprofen, naproxen,)
    (induce GI bleeding by inhibiting cyclooxygenase activity = toxic)
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16
Q

why might anaemia develop from reticuloendothelial system

A
  • in haemolytic anaemias RBCs destroyed more quickly as abnormal or damaged
  • damage can occur in blood vessels (intravascular) or in RES (extravascular)
  • autoimmune anaemia causes antibodies to bind to RBC mem so recognised by spleen
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17
Q

what two factors can help determine cause of anaemia

A

RBC size
presence or absence or reticulocytes

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18
Q

what are reticulocytes

A

immature RBC
- no nucleus and eliminate remaining mitochondria
- take one day to mature

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19
Q

what are the causes of macrocytic anaemia

A
  • Vit B12 def
  • folate def
  • myelodysplasia
  • liver diease
  • alcohol toxicity
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20
Q

what are the three types of macrocytic anaemias

A
  • megaloblastic
  • macronormoblastic
  • stress
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21
Q

what is macrocytic anaemia

A

where average size of RBC is greater than normal so higher MCV

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22
Q

what is megaloblastic anaemia

A
  • interfers with DNA synth during erythropoiesis during development of nucleus so nuceluar, cytoplasmic dssynchrony as cell division delayed but cell continues to grow = larger cells = megaloblasts
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23
Q

what are examples of causes of macrocytic anaemia

A
  • Vit B12/ folate def
  • drugs that interfer with DNA synth
  • erythroid leukaemias
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24
Q

what is macronormoblastic anaemias

A

larger erythroblasts are larger than normal and give rise to larger than red cells

25
Q

what are examples of causes of macronormoblastic anaemia

A
  • liver disease
  • alcohol toxicity
  • myelodysplastic
26
Q

what is stress erythropoiesis

A

conditions associated with a high reticulocyte count (reticulocytes are larger than RBCs)
- high level of erythropoeitin leads to expanded and accelerated erthyropoeisis

27
Q

what are examples of causes of stress erythropoiesis

A
  • recovery from blood loss due to haemorrhage
  • recovery from haemolytic anaemia
28
Q

what is folate

A

synthetic form of folic acid

29
Q

where is folate synthesised

A

bacteria and plants

30
Q

where is folate present

A

variety if animal and vegetable food sources mainly leafy greens

31
Q

where is folate absorbed

A

mainly duodenum and jejunum

32
Q

what is folate converted to by intestinal cells

A

tetrahydrofolate

33
Q

where is folate stored

A

liver

34
Q

what is folate important for

A

recipient reactions include synth of nucleotides for DNA and RNA synthesis

35
Q

what are the causes of folate deficiency

A
  • poor diet
  • increased requirement (preg, increased erythropoiesis, skin disease)
  • diseases of duodenum and jejunum (coeliac, crohns)
  • alcoholism
  • liver disease and heart failure
36
Q

what symptoms of folate def

A
  • related to anemia
  • reduced tase
  • diarrhoea
  • numb feet and hands
  • muscle weakness
  • depression
37
Q

when is folate especially important to take

A

before contraception and during first 12 weeks of pregnancy

38
Q

why is folate important for pregnancy

A

prevents majority of neural tube defects

39
Q

what is vitamin B12 required for

A
  • cofactor for DNA synthesis (due to role in folate metabolism
  • required for normal erythropoiesis
  • normal function and development of CNS
40
Q

what is vit B12 produced by

A

bacteria but largerly obtained from animal origin from commensal bacteria in animal stuff

41
Q

how is B12 released from food

A

proteolysis in stoach

42
Q

what does B12 bind to after it is released from food in stomach

A

haptocorrin

43
Q

what is the haptocorrin B12 complex digested by

A

pancreatic proteases in small intestine

44
Q

what does B12 bind to after the haptocorrin complex is digested

A

intrinsic factor produced by gastric parietal

45
Q

what does the intrinsic factor B12 complex bind to

A

cubam receptor which mediates uptake of complex by receptor mediated endocytosis into enterocytes

46
Q

after lysosomal release in enterocytes ho does B12 exit the basolateral mem

A

through MDR1

47
Q

what does B12 bind to after exiting through MDR1

A

transcobalamin in blood

48
Q

how long can the store of B12 last for

A

3-6 years

49
Q

what are the causes of B12 def

A
  • diet (mainly vegans)
  • lack of intrinsic factor (pernicious anaemia)
  • diseases of ileum
  • lack of transcobalamin
  • chemical inactivation
  • parasite
  • some drugs can chelate intrinsic factor
50
Q

what is pernicious anaemia

A

decreased or absent intrinsic factor causes progressive exhaustion of B12

  • autoimmune disease
51
Q

what are the sympoms of vit B12 def

A
  • anaemia symptoms
  • glossitis and mouth ulcers
  • diarrhoea
  • paraesthesia
  • disturbed vision
  • irritable
52
Q

what is subacute combined degeneration of the cord

A

degeneration of posterior and lateral columns of spinal cord

53
Q

what is subacute combined degeneration of the cord caused by

A

B12/ folate def

  • 12 can cause demyelination
  • folate de can cause neural defects in preg
54
Q

what are the symptoms of subacute combined degeneration of the cord

A

onset weakness , numb, arms, legs and trunk

changes in mental state

55
Q

how are B12 and folate linked

A

Vit B 12 is required to convert methyltetrahydrofolate (stable) tetrahydrofolate

56
Q

how does a def in B12 affect folate cycle

A

lack of B12 will trap folate in stable methyltetrahydrofolate form preventing conversion to tetrahydrofolate to be used in other reactions such as synthesis of thymidine for DNA synthesis

57
Q

why do B12 and folate def cause megaloblastic anaemia

A
  • lead to thymidine def
  • absence of thymidine uracil is added to DNA
  • DNA repair enzyes detect and repair by excision
  • asynchronous maturation between nucleus and cytoplasm (nuc does not mature with ope chromatin)
58
Q

how to treat folate def

A

oral folic acid

59
Q

how to treat vit B12 def

A
  • pernicious anaemia : hydroxycobalamine intramuscularly NOT ORALLY as will not absorb
  • other causes : oral cyanocobalamine

MEH (12 decks)

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