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Year 2 MCD Haematology > B12+ Folic acid deficiency > Flashcards

B12+ Folic acid deficiency Flashcards

1
Q

What is the physiological function of Vitamine B12?

A
  1. DNA synthesis
    * involved in thymine synthesis
  2. Integrity of the nervous system
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2
Q

What is the physiological function of folic acid?

A
  • DNA Synthesis
    • needed for thymine generation
  • Homocystine metabolism
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3
Q

Which cells are primarily affected by a Vit B12 and Folic acid deficiency?

A

Because of role in DNA synthesis–> all rapidly dividing cells are affected! (need more DNA synthesis)

  • ŸBone marrow
  • ŸEpithelial surfaces of mouth and gut
  • ŸGonads
  • Ÿembryos
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4
Q

What are the clinical features or a B12 or Folic acid deficiency?

A
  • Anemia: weak, tired, short of breath
  • Jaundice
  • Glossitis and angular cheilosis
  • Weight loss, change of bowel habit
  • Sterility –> expecially in male (spermatogenesis)
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5
Q

What is a megaloblastic anaemia?

A
  • Type of anaemia only present in B12 or Folic acid deficiency
    • change in the red cell precursors within the bone marrow
    • leads to an asynchronous maturation of the nucleus and cytoplasm of erythrocytes (e.g. might see mature erythrocyte with nucleus)
    • maturing erythrocytes seeing in circulaiton
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6
Q

Which changes to the blood film might occur in a megaloblastic anaemia?

A
  • Anisocytosis (unequal size)
  • large cell size
  • hypersegmented neutrophils (>5 secments in nucleus) –> picture
  • Giant metamyelocytes (precursor of ganulocytes)
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7
Q

What are possible causes for macrocytic anaemia?

A
  • Vitamin B12/folate deficiency
  • Liver disease or alcohol
  • Hypothyroid
  • Drugs e.g. azathioprine
  • Haematological disorders:
    • ŸMyelodysplasia,
    • Ÿaplastic anemia
    • ŸReticulocytosis e.g. chronic haemolytic anemia
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8
Q

What are possible causes for a megaloblastic anaemia?

A

Mainly: Vit B12 and Folic acid deficiency

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9
Q

Which test would you perform in someonw with a macrocytic anaemia?

A
  • B12/Folate acid levels
  • Thyroid test
  • liver function test
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10
Q

What is the source of folate acid?

A

Diatary source in (uncooked) fresh, green leafy vegetables

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11
Q

When does the folic acid requirement increase?

A
  1. Physiologically
    • pregnancy
    • adolescence
    • premature babies
  2. Pathologically
    • malignancy–> more production of cells
    • erythoderma (eczemas)
    • haemolytic anaemias –> more production of cells
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12
Q

In which patients do you normally see a folic acid deficiency?

A
  • Ignorance
  • alcoholics, elderly–> don’t take care of themselves
  • poor – >poor diet
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13
Q

How would you diagnose someone to have a folate deficiency?

A

FBC and Blood film

macrocytic, megaloblastic anaemia

Folate acid levels

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14
Q

How to you investigate the cause of a folate acid deficiency?

A
  • EASY – history (diet/alcohol/illness)
  • EXAMINATION – skin disease/ alcoholic liver disease
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15
Q

What are the consequences of folate deficiencies?

A

Macrocytic, megaloblastic anaemia but also

  • neural tube defects in developing fetus
  • increased risk of thrombosis in association with variant enzymes involved in homocysteine metabolism
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16
Q

Explain the relationship between homocysteine and folic acid

A

Folic acid is needed for homocystein metabolism

In folic acid deficiency:

  • increase of homocystein leading to
    • atherosclerosis, vascular disease, likely thrombosis
17
Q

What are the possible consequences of vitamine B12 deficiency?

A

Countless neural symptoms –>

  • ŸBilateral peripheral neuropathy
  • ŸSubacute comined degeneration of the cord
    • Posterior and pyramidal tracts of the spinal cord
  • ŸOptic atrophy
  • Ÿdementia
  • Paraesthesiae
  • Muscle weakness
  • Difficult walking
  • Visual impairment
  • Psychiatric disturbance
18
Q

How does someoe with a severe vitamine B12 deficiency present on examination?

A

Absent peripheral reflexes and upgoing plantar responses

but also

  • glossitis
  • tingeling fingers
  • auto-immune dieseaes
  • §Premature grey hair
  • falling over when closing eyes, loss or proprioception
19
Q

What are the possible cuases for a vit B12 deficiency?

A
  1. Poor absorbtion
  2. Low intake
    • vegan diet
  3. Infectsions
    • mainly parasites
20
Q

What might be possible causes for a malabsorbtion of vitamine B12?

A
  1. Reduction of Intrinsic factor
    • post gastrectomy
    • gastric atrophy
    • antibodies to intrinsic factor or parietal cells –> autoimmune (common)
  2. ​Diseases of small bowel (terminal ileum)
    • Crohns
    • Coeliac disease
    • surgical resection
  3. Infections
    • H Pylori
    • Giardia
    • Fish tapeworm
    • Bacterial overgrowth
  4. Drugs
    • ​metformin (diabetis)
    • omenprazon (anti-acid)
    • oral contraceptive pill
21
Q

What is pernicious anaemia?

A

Anaemia due to Vit B12 deficiency, caused by autoimmune destruction of Intrinstic facotor

Normall in

  • ŸPeak age: 60 years
  • ŸFamily history or auto-immune disease
22
Q

How do you call the diese in patients with low IF due to autoimmune destruction of it?

A

Pernicious anaemia

–> also increased risk of Stomach Ca

23
Q

Which investigations would you perform in someone with a B12 deficiency?

A

What is the cause of B12 deficiency?

  1. History (e.g. vegan diet) –> easy
  2. Antibodies to parietal cells and intrinsic factor (IF destruction?)
  3. Anitbodies for coeliac disease (malabsorbtion)
  4. Breath test for bacterial overgrowth
  5. Stool for H Pylori
  6. Test for Giardia

OLDEN DAYS - Shilling test (part I and part II)

24
Q

What is the Shilling test?

When is it done?

A

Now: outrun , not performed anymore (radioactive)

It can investivate the absorbtion of Vit. B12, is done in Vit. B12 anaemia

  • After high dose B12 injections–>
    radioactive oral administration of B12
  • excretion in urine is measured
    • if urine radioactive –> absorbation possible
    • if not–> malabsorbtion or no adherence to previous injections (no excretion of B12 due to still deficiency)
25
Q

How do you treat someone with a vit B12 deficiency?

A

High dose IM injection of Vitamine B12

  • 3x/week for 2 weeks
  • Thereafter every 3 months

In neurological problems

  • B12 injections alternate days until no further improvement – up to 3 weeks
  • Thereafter every 2 months
26
Q

What is the pyhsiolocial role of B12?

A

Als Methylcobalamin dient es der Methioninsynthase als Coenzym bei der Methylierung von Homocystein zu Methionin. Der Methylgruppendonor ist dabei N5-Methyltetrahydrofolat (N5-Methyl-THF). Und als Adenosylcobalamin dient Vitamin B12 bei der Umwandlung von Methylmalonyl-CoA zu Succinyl-CoA durch die Methylmalonyl-CoA-Mutase der Einschleusung von Propionyl-CoA (aus dem Abbau ungeradzahliger Fettsäuren und einiger Aminosäuren) in den Citratzyklus.

Year 2 MCD Haematology (14 decks)

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