Anaemia, B12 and Folate Flashcards
Define anaemia
Haemoglobin conc. lower than the normal range
varies with age, sex and ethnicity
What are the signs of anaemia?
- Pallor
- Tachycardia
- Systolic flow murmur
- Tachypnoea
- Hypotension
What are the symptoms of anaemia?
- Shortness of breath
- Palpitations
- Headaches
- Claudication
- Angina
- Lethargy
- Weakness
What is Koilonychia?
Spoon shaped nails associated with iron deficiency
What is angular stomatitis?
Inflammation of the corners of the mouth associated with iron deficiency
What is glossitis?
Inflammation and depapillation of tongue associated with Vit B12 deficiency
What are the 6 causes of the development of anaemia?
1) Reduced of dysfunctional erythropoiesis
2) Defects in haemoglobin synthesis
3) Abnormal structure and mechanical damage resulting in haemolysis
4) Defects in red cell metabolism
5) Excessive bleeding
6) Reticuloendothelial system increased removal
What are the 2 key features looked for when evaluating anaemia?
1) RBC size (macrocytic, microcytic, normocytic)
2) Presence or absence of reticulocytes = shows bone marrow is functioning
What is macrocytic anaemia?
Anaemia whereby the average red cell size is greater than normal
What are the three types of macrocytic anaemia and where do they derrive from?
1) Megaloblastic anaemia = asynchronous maturation between nucleus and cytoplasm; from Vit B12/folate deficiency, drugs that interfere DNA synthesis
2) Macronormoblastic erythropoiesis = normal nucleus + cytoplasm growth but erythroblastosis are larger than normal; from liver disease, alcohol toxicity
3) Stress erythropoiesis = high reticulocyte count from high levels of erythropoietin causing accelerate erythropoiesis (reticulocytes larger); from recovery from blood loss, recovery from haemolytic anaemia
What is folate and what is it used for?
A B vitamin (B9) synthesised by bacteria and plants used for nucleotide base synthesis for RNA+DNA synthesis
Where is folate absorbed?
duodenum and Jejunum
What are the causes of folate deficiency?
- poor diet
- increased requirement (e.g. pregnancy)
- disease of duodenum/jejunum (e.g. Crohn’s)
- drugs that inhibit dihydrofolate reductase
- alcoholism
- liver disease
What are the symptoms of folate deficiency?
- anaemia-related symptoms
- diarrhoea
- numbness or tingling
- muscle weakness
- depression
What is Vitamin B12 and what is it used for?
Water soluble B vitamin that acts as a cofactor for DNA synthesis
It’s required for normal erythropoiesis and essential for normal CNS function and development
What are some good sources of Vitamin B12?
- meat
- fish
- milk
- egg
- cheese
- yeast extract
Describe the absorption of Vitamin B12
1) B12 released from protein in diet (proteolysis) the binds to
HAPTOCORRIN
2) B12-haptocorrin complex cleaved by pancreatic proteases, B12 then binds to INTRINSIC FACTOR
3) Intrinsic factor-B12 complex then enter intestinal cell by receptor mediated endocytosis (CUBAM RECEPTOR)
4) B12-intrinsic factor complex cleaved
5) B12 binds to TRANCOBALAMIN 2 to travel blood
6) B12 leaves via MDR1
What are the causes of B12 deficiency?
- poor intake e.g. vegans
- lack of intrinsic factor
- ileum diseases e.g. Crohn’s
- lack of transcobalamin
- chemical inactivation of B12
- parasitic infection
- drugs that chelate intrinsic factors
What are the symptoms of B12 deficiency?
- anaemia-related symptoms
- glossitis and mouth ulcers
- irritability
- diarrhoea
- disturbed vision
- paraesthesia
What is Pernacious anaemia?
Autoimmune disease where there is decreased/absence of intrinsic factors leading to exhaustion of reserves
Why is folic acid important for pregnancy?
To prevent neural tube defects
Describe the B12-Folate link
- Vit B12 is important for the methionine cycle (important for methylated products such are adrenaline, creatine and melatonin)
- Folate cycle drives formation of Thymidine required for DNA synthesis
- Methionine cycle and folate cycle linked
- Lack of B12 ‘traps’ folate in a stable form and can’t go through the folate cycle to drive thymidine synthesis
What would be seen in a FBC of megaloblastic anaemia?
- increased plasma lactate dehydrogenase
- increased bilirubin
- low haemoglobin
Folate deficiency treatment
Oral folic acid
Vitamin B12 deficiency treatment
Hydroxycobalamine intramuscular injection for pernicious anaemia and Cyanocobalamine orally for others
