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Haem > B12 and folate deficiency > Flashcards

B12 and folate deficiency Flashcards

1
Q

What is B12 required for?

A

DNA synthesis

The integrity of the nervous system

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2
Q

What is folic acid required for?

A

DNA synthesis

Homocysteine metabolism

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3
Q

Which cells are affected by a deficiency in folate and B12?

A

All rapidly dividing cells:

  • bone marrow
  • Epithelial surfaces of mouth and gut
  • Gonads
  • Embryos
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4
Q

What are the clinical features of folate and B12 deficiency?

A 
Anemia - weak + tired 
Jaundice 
Sterility 
Glossitis and angular cheilosis
Weight loss, change of bowel habit
Sterility
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5
Q

What it is the size of the red blood cell in folate and B12 deficiency?

A

High MCV

Macrocytic - red cell size bigger than normal

megaloblastic

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6
Q

What are the causes of macrocytic anaemia?

A 
Vitamin B12/folate deficiency
Liver disease or alcohol
Hypothyroid
Drugs e.g. azathioprine
Haematological disorders:
Myelodysplasia, 
aplastic anaemia
Reticulocytosis e.g. chronic haemolytic anaemia
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7
Q

What does megaloblastic mean?

A

Describes the morphological changes in red cells precursors in the bone marrow.

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8
Q

What are the peripheral changes in megaloblastic anaemia?

A

Anisocytosis
Large red cells
Hypersegmented neutrophils
Giant metamyelocytes

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9
Q

If someone had macrocytosis you would investigate:

A

B12
Folate
Thyroid function test
Liver function test

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10
Q

What are two causes of hypersegmented neutrophils?

A

B12 and folate deficiency

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11
Q

Where can you find dietary folate?

A

Fresh leafy vegetables

Destroyed by: overcookinh/canning/processing

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12
Q

Who is at risk of folate deficiency?

A

Ignorance
Poverty
Apathy

Elderly + alcoholics

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13
Q

When would you have increased demand in folate?

A

PHYSIOLOGICAL
Pregnancy
Adolescence
Premature babies

PATHOLOGICAL
Malignancy
Erythoderma
Haemolytic anaemias

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14
Q

How would you diagnose low folate levels?

A

FBC - look at the folate levels

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15
Q

What are the consquences of folate deficiency?

A

Megaloblastic + macrocytic anaemia

Neural tube defects in developing fetus (Spina bifida
Anencephaly - pregnant women told to take doses of folic acid)

Increased risk of thrombosis in association with variant enzymes involved in homocysteine metabolism

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16
Q

What is homocysteine associated with?

A

atherosclerosis

premature vascular disease

17
Q

What are consequences of B12 deficiency?

A

Neurological problems

Optic atrophy

Dementia

Common history includes:

Paraesthesiae
Muscle weakness
Difficult walking
Visual impairment
Psychiatric disturbance
18
Q

What are causes of B12 deficiency?

A

Poor absorption - across the duodemum (very slow), most of it is by binding to the intrinsic factor (made in parietal cells in the stomach), this binds to ileal receptors- this is much faster

Reduced doetary intake - vegans not vegetarians as animal produce is rich in b12.

Infections/infestations

19
Q

What three things are essential for the absorption of B12?

A

Intact stomach
Intrinsic factor
Functioning small intestine

20
Q

What can cause a decrease in absorption of intrinsic factor?

A

a) post gastrectomy
b) gastric atrophy
c) antibodies to intrinsic factor or parietal cells

21
Q

What is pernicious anaemia?

A

The autoimmune condition associated with SEVERE LACK OF IF

22
Q

What are the tests for pernicious anaemia?

A

Intrinsic factor antibodies

Parietal cell antibodies

23
Q

What can be an alternative explanation to the lack of absorption of B12?

A

Diseases of small bowel (terminal ileum)

a) Crohns
b) Coeliac disease
c) surgical resection

Infections:
H Pylori
Giardia
Fish tapeworm
Bacterial overgrowth

Drugs:

  • Metformin
  • Omeprazole
24
Q

What is the schilling’s test?

A

Drink radiolabelled B12

Measured excretion in the urine - if absorbed then the radioactivity will be in the urine but if there is no B12 in the urine then this will pass straight to the poo.

25
Q

If the B12 levels are normal the patient can still be deficient in B12 how would you test for this?

A

Measure methylmalonyl acid
Measure homocysteine
Look for anti-intrinsic factor antibodies

Haem (12 decks)

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