Macrocytic Megalobastic anaemia Flashcards

1
Q

What is B12 deficiency anaemia

A

Anaemia (low levels of Hb in the blood) caused by B12 deficiency.

This is a macrocytic megaloblastic anaemia.

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2
Q

Epidemiology of B12

A
  • Found in meat + dairy - bad 4 vegans
  • Vitamin B12 deficiency increases with age.
  • Unlike folate, vitamin B12 stores last for years before deficiency develops.
  • B12 deficiency most commonly due to pernicious anaemia
  • Pernicious anaemia: relatively common amongst Northern Europeans, with a high prevalence in those aged 60-70 years old
  • F>M
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3
Q

Vitamin B12 pathophysiology

A

essential vitamin for DNA synthesis in cells undergoing rapid proliferation

Deficiency of Vitamin B12 affects rapidly dividing cells, such as those in the bone marrow. This can lead to pancytopenia. As compensation for anaemia, the bone marrow produces abnormal precursors of RBCs - macrocytic, megaloblastic RBCs

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4
Q

B12 + Neuro

A

Keeps levels of methylmalonic acid low > high levels can lead to:
- Peripheral neuropathy
- Subacute degeneration of the cord
- Focal demyelination

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5
Q

Causes of B12 deficiency

A
  • Inadequate intake(e.g. strict vegetarians, vegans)
  • Inadequate secretion of intrinsic factor(e.g. pernicious anaemia, gastrectomy)
  • Malabsorption(e.g. Crohn’s, tropical sprue, patients who have had gastric bypass)
  • Inadequate release of B12from food(e.g. gastritis, alcohol abuse
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6
Q

What is pernicious anaemia

A

Pernicious anaemia (PA) refers to vitamin B12 deficiency as a result of autoimmune destruction of the gastric epithelium. This may be due to anti-parietal cell antibodies or anti-IF antibodies.

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7
Q

What do patients with PA develop?

A

chronic gastric inflammation, which may lead to gastric atrophy. Over time, the basal secretion of IF is severely decreased leading to the development of vitamin B12 deficiency.

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8
Q

S + S of b12

A

Signs: Pallor, confusion, ataxia
Symptoms: General anaemia stuff
+ CNS involvement= Depression, memory loss, personality change

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9
Q

1st line investigations for B12

A
  • Full blood count (FBC): raised MCV
  • Blood film: megaloblastic anaemia +/- hypersegmented neutrophils
  • Haematinics: look for iron, B12, folate deficiency
  • Lactate dehydrogenase (LDH): may be elevated
  • Liver function tests (LFTs)
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10
Q

Management of B12

A
  • Treatment of the underlying cause
  • B12 supplementation e.g. oral cyanocobalamin; intramuscular hydroxocobalamin
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11
Q

What is folate deficiency anaemia?

A

Anaemia (low levels of Hb in the blood) caused by folate (vitamin B9) deficiency. This is a type of macrocytic megaloblastic anaemia

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12
Q

Epidemiology of Folate deficient anaemia

A
  • In general, megaloblastic anaemia and folate deficiency are seen most commonly in countries where malnutrition is problematic.
  • High-risk patient groups include: children, pregnant women and the elderly.
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13
Q

RF of Folate

A
  • Elderly
  • Poverty
  • Alcoholic
  • Pregnant
  • Crohn’s or coeliac disease
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14
Q

What is Folate (vitamin B9) important for?

A

important molecule which acts as a cofactor in amino acid metabolism and DNA/RNA synthesis.

BM affected hard since most active for cell division - leads to pancytopenia

Response to anaemia - BM compensates and releases megaloblasts in blood leading to macrocytic megaloblastic anaemia

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15
Q

Other folate pathology

A
  • Other rapidly dividing cells, include mucosal epithelial cells of the tongue. These are affected, preventing healing. This leads to glossitis.
  • Folate is also essential for foetal development - deficiency can result in neural tube defects e.g. spina bifida. So supplementation is essential during pregnancy!
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16
Q

Causes of folate defiency

A
  • Inadequate intake
  • Malabsorption(e.g. coeliac disease, resection)
  • Increased requirements(e.g. pregnancy, malignancy disease)
  • Increased loss(e.g. Chronic liver disease)
  • Other(e.g. anti-convulsants, alcohol abuse)
17
Q

S + S of folate

A

Sign - pallor
Symptom - fatigue, SOB, palpitations, headache

18
Q

Primary investigations for Folate

A
  • FBC: high MCV
  • Blood film: macrocytic, megaloblastic RBC
  • Haematinics: search for iron, B12 and folate deficiencies
  • Serum and red cell folate: low
19
Q

Management of folate

A
  • Treat underlying cause e.g. stopping drugs or alcohol consumption
  • Folic acid supplements: always give alongside B12, because replacement of folic acid in the presence of vitamin B12 deficiency may cause significant neurological disease.