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Year 2 haem mine > Vitamin B12 and folic acid deficiency > Flashcards

Vitamin B12 and folic acid deficiency Flashcards

1
Q

what are the roles of vit B12 and folate

A

Required for DNA synthesis

Absence leads to severe anaemia which can be fatal

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2
Q

B12 required for

A
  1. DNA synthesis

2. Integrity of the nervous system

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3
Q

folic acid required for

A

DNA Synthesis

Homocystine metabolism

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4
Q

what are the clinical features of B12/folate deficiency

A 
Anemia: weak, tired, short of breath
Jaundice
Glossitis and angular cheilosis
Weight loss, change of bowel habit
Sterility
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5
Q

what cells does B12 and folate deficiency effect?

A 
ALL RAPIDLY DIVIDING CELLS ARE AFFECTED
Bone marrow
Epithelial surfaces of mouth and gut
Gonads
embryos
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6
Q

what does deficiency of B12 or folate lead to?

A

ANEMIA

This is macrocytic and megaloblastic

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7
Q

what is macrocytic mean?

A

Average red cell size is above the normal range

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8
Q

what can cause macrocytic anemia?

A 
Vitamin B12/folate deficiency
Liver disease or alcohol
Hypothyroid
Drugs e.g. azathioprine
Haematological disorders:
-Myelodysplasia, 
-aplastic anemia
-Reticulocytosis e.g. chronic haemolytic anemia
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9
Q

what does megaloblastic mean?

A

Describes a morphological change in the red cell precursors within the bone marrow

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10
Q

what is the order for normal red cell maturation?

A

Erythroblast
Normoblast: early/intermediate/late
Reticulocyte
Circulating red blood cell

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11
Q

what is megaloblastic anemia?

A

Defined by asynchronous maturation of the nucleus and cytoplasm in the erythroid series.

Maturing red cells seen in the bone marrow

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12
Q

what are the features in peripheral blood in megaloblastic anaemia?

A

Anisocytosis
Large red cells
Hypersegmented neutrophils
Giant metamyelocytes

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13
Q

what would define hypersegmented neutrophil?

A

neutrophil with 5 or more segments/lobes

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14
Q

where do you get dietary folate from?

A

Fresh leafy vegetables

Destroyed by overcooking/canning/processing

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15
Q

folate: decreased intake reasons:

A

IGNORANCE
POVERTY
APATHY

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16
Q

what are some common reasons for increased demands of folate?

A

PHYSIOLOGICAL
Pregnancy
Adolescence
Premature babies

PATHOLOGICAL
Malignancy
Erythoderma
Haemolytic anaemias

17
Q

Laboratory diagnosis of folate deficiency

-what would you use?

A

FBC and film

Folate levels in the blood

18
Q

assessing cause of decreased folate:

A

EASY – history (diet/alcohol/illness)

EXAMINATION – skin disease/ alcoholic liver disease

19
Q

consequences of folate deficiency:

A

Megaloblastic, macrocytic anemia

Neural tube defects in developing fetus

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

20
Q

what can neural tube defects lead to

A

Spina bifida
Anencephaly

ALL PREGNANT WOMEN TAKE FOLIC ACID 0.4MG PRIOR TO CONCEPTION AND FOR FIRST 12 WEEKS

21
Q

what are high homocysteine levels associated with?

A

Very high homocysteine levels are associated with
atherosclerosis
premature vascular disease

Mildly elevated levels of homocysteine are associated with:
cardiovascular disease DEFINITELY
arterial thrombosis PROBABLY
venous thrombosis POSSIBLY

22
Q

what are the consequences of B12 deficiency

A

Neurological problems
Bilateral peripheral neuropathy
Subacute comined degeneration of the cord
Posterior and pyramidal tracts of the spinal cord
Optic atrophy
dementia

23
Q

example of symptoms in B12 deficiency history

A 
Paraesthesiae
Muscle weakness
Difficult walking
Visual impairment
Psychiatric disturbance
24
Q

what do you find upon examination of B12 deficient patient

A

Absent reflexes and upgoing plantar responses

25
Q

B12 Deficiency cause

A 
POOR ABSORPTION
Reduced dietary intake
Stores are large and last for 3-4 years
Animal produce
Vegans are at risk

Infections/infestations
Abnormal bacterial flora (stagnant loops)
Tropical sprue
Fish tapeworm

26
Q

what is normal B12 absorption?

A

Occurs in small intestine – B12 is then stored – when stores are saturated excess B12 is excreted in the urine
2 methods of absorption
Method 1 - Slow and inefficient (1%)
- duodenum

Method 2..most absorption this way.

B12 must combine with intrinsic factor
Intrinsic factor is made in the stomach
(parietal cells)
B12-IF binds to ileal receptors

27
Q

3 key things for B12 absorption to occur

A

THREE THINGS ARE ESSENTIAL
Intact Stomach
Intrinsic factor
Functioning small intestine

28
Q

what can cause reduction in intrinsic factor?

A

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

29
Q

what is pernicious anemia?

A

Autoimmune condition associated with SEVERE LACK OF IF

Peak age: 60 years
Family history

Males have a decreased life expectancy- increased risk of cancer in stomach

30
Q

what conditions may lead to impaired B12 absorption

A

Diseases of small bowel (terminal ileum)

	a) Crohns
	b) Coeliac disease
	c) surgical resection
31
Q

infections that might cause B12 deficiency

A

H Pylori
Giardia
Fish tapeworm
Bacterial overgrowth

32
Q

Drugs associated with low B12

A

Metformin
Proton pump inhibitors e.g. omeprazole
Oral contraceptive pill

33
Q

what is the procedure you’d carry out in patients with low B12

A

What is the cause of B12 deficiency?
Antibodies to parietal cells and intrinsic factor
Anitbodies for coeliac disease
Breath test for bacterial overgrowth
Stool for H Pylori
Test for Giardia
OLDEN DAYS - Shilling test (part I and part II)

34
Q

what do you do in shilling test part 1

A

Prior to test, replenish stores

	a) drink radiolabelled B12
	b) measure excretion in the urine
35
Q

what if you dont measure B12 in urine part 1 schilling

A
  1. Not absorbing B 12
    - pernicious anaemia
    - small bowel disease
  2. Hadn’t corrected B 12 deficiency before the test
36
Q

schilling test part 2

A

Repeat test with addition of intrinsic factor

Measure excretion of B12 in the urine

37
Q

classic case but normal B12

A

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

Treat as B12 deficiency until you get all of the results back

38
Q

treatment for B12 deficiency

A

Injections of B12…. 1000ug (i.m)
3x/week for 2 weeks
Thereafter every 3 months

IF NEUROLOGICAL INVOLVMENT
B12 injections alternate days until no further improvement – up to 3 weeks
Thereafter every 2 months

Year 2 haem mine (11 decks)

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