Macrocytic Megalobastic anaemia Flashcards
What is B12 deficiency anaemia
Anaemia (low levels of Hb in the blood) caused by B12 deficiency.
This is a macrocytic megaloblastic anaemia.
Epidemiology of B12
- 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
Vitamin B12 pathophysiology
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
B12 + Neuro
Keeps levels of methylmalonic acid low > high levels can lead to:
- Peripheral neuropathy
- Subacute degeneration of the cord
- Focal demyelination
Causes of B12 deficiency
- 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
What is pernicious anaemia
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.
What do patients with PA develop?
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.
S + S of b12
Signs: Pallor, confusion, ataxia
Symptoms: General anaemia stuff
+ CNS involvement= Depression, memory loss, personality change
1st line investigations for B12
- 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)
Management of B12
- Treatment of the underlying cause
- B12 supplementation e.g. oral cyanocobalamin; intramuscular hydroxocobalamin
What is folate deficiency anaemia?
Anaemia (low levels of Hb in the blood) caused by folate (vitamin B9) deficiency. This is a type of macrocytic megaloblastic anaemia
Epidemiology of Folate deficient anaemia
- 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.
RF of Folate
- Elderly
- Poverty
- Alcoholic
- Pregnant
- Crohn’s or coeliac disease
What is Folate (vitamin B9) important for?
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
Other folate pathology
- 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!