Iron, B12 and Folate Flashcards
What three functional groups are needed in a red cell and why?
Iron, amino acids and blasts
Iron and amino acids form haemoglobin
Blasts needed for DNA synthesis and dividing cells
How is iron mainly stored?
Haemoglobin (65%), ferritin (20-30%)
How is iron absorbed into the body?
1) non-haem in Fe3+ converted into Fe2+ via ferric reductase (haem-iron just absorbed)
2) DMT-1 transports Fe2+ into enterocyte
3) Fe2+ binds to binding protein
4) Fe2+ leaves enterocyte via ferroportin-1
5) Haphaestin converts Fe2+ into Fe3+
6) Fe3+ binds to transferrin to move iron around in plasma to tissues
7) ferritin stores iron intracellularly and releases iron when it’s low
What are the disease outcomes when iron, amino acids and blasts are not functional?
Iron deficiency
Thalassaemias
Megablastic anaemias
What compound is made from liver and decreases iron absorption and how does it work?
Hepcidin made by liver
Downregulates iron absorption
It inhibits ferroportin-1so reduced iron in plasma
What may be seen on a blood film in iron deficiency?
Hyperchromic - decreased hb so pale cells
In bloods, what would be high and low in microcytic anaemia iron deficiency?
Low-
MCV
Serum Fe
Ferritin
BM iron
High
Transferrin
soluble transferrin receptor
In bloods, what would be high and low in microcytic anaemia of chronic disease?
Low; MCV, serum fe, transferrin,
High: ferritin
Normal: MCV, FERRITIN, sTf-R, BM iron
In bloods, what would be high and low in microcytic anaemia in thalassaemia trait?
Low; MCV, sTf-R
High; BM iron
Normal: serum Fe, transferrin, ferritin
In bloods, what would be high and low in microcytic anaemia sideroblastic anaemia?
Low: MCV
High: MCV, Serum Fe, ferritin
Normal,: transferrin, sTf-R, BM iron
Main causes of iron deficiency?
Inadequate diet
Increased requirements (growth, pregnancy)
Malabsorption
Blood loss (menstrual, GI, urinary, lung)
What GI investigations are there for causes of iron deficiency?
Drug history (NSAIDS, aspirin, bisphosphonates)
Faecal haemoglobin
Tissue transglutaminase antibody
Gastroscope
GI causes for iron deficiency anaemia?
Hookworm infections
Cancers
Coeliac and chrons
Gastritis
Peptic ulcers gastrectomy
Colitis
Etc
Treatment for iron deficiency?
Oral ferrous sulphate 3 months post Hb-normalisation OD
IV infusion if oral not work. Ferric carboxymaltose; ferric derisomaltose
What is folic acid and where is it found in diet?
In green veg, and needed for DNA synthesis
It forms deoxyuridine as a precursor for thymine dna base
What investigations are carried out if GI involvement is suspected?
Drug history (NSAIDS, aspirin, bisphosphonates)
Faecal haemoglobin
Tissue transglutaminase antibody (tTG) (for coeliac disease)
Imaging (Gastroscopy)
Stool for parasites
How is folate absorbed into the body?
Absorbed in jejunum and is methylated in order to be absorbed
What is the role of B12 in folate absorption?
Methyl THF is transmethylated by B12 (which forms methionine from homocysteine) to form THF to go on form DNA bases
Where is B12 absorbed and how?
R factors binds to B12 in stomach. Intrinsic factor released from parietal cells in stomach. R factors unbind from B12 in intestine. IF binds to B12 in terminal ileum absorption
Affects of B12 and folate deficiency?
Affects rapidly dividing cells the most (bone marrow precursors and gut epithelium)
Can cause neuropathy and optic atrophy specific for B12
Deficiency of both can cause confusion in elderly
What is the treatment for B12 deficiency?
Parenteral hydroxycobalamin, 3 monthly
Can give prophylaxis after GI resection
What is the treatment for folic acid?
Oral folic acid 4 months or continuously
Prophylaxis - preconception and pregnancy (400mg OD) (neural tube defects)
If pt has coeliacs and pregnant, 500mg OD.
Colonic acid for DHF-reductase inhibition (methotrexate)
Main causes of folate deficiency?
Diet
Increased utilisation (physiological/pathological)
Malabsorption
Urinary loss
Drugs (methotrexate)
Main causes of B12 deficiency?
Diet
Gastric disease
Ideal disease
Infections (bacterial overgrowth in small bowel/ fish tapeworm)
Pancreatic disease
B12 destruction via nitrous oxide
What must you check before prescribing folic acid?
B12 levels - folic acid can mask B12 deficiency ans can lead to sub acute combined spinal chord degeneration
