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Y2 Haematology > Iron, B12 and Folate > Flashcards

Iron, B12 and Folate Flashcards

1
Q

What three functional groups are needed in a red cell and why?

A

Iron, amino acids and blasts
Iron and amino acids form haemoglobin
Blasts needed for DNA synthesis and dividing cells

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2
Q

How is iron mainly stored?

A

Haemoglobin (65%), ferritin (20-30%)

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3
Q

How is iron absorbed into the body?

A

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

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4
Q

What are the disease outcomes when iron, amino acids and blasts are not functional?

A

Iron deficiency
Thalassaemias
Megablastic anaemias

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5
Q

What compound is made from liver and decreases iron absorption and how does it work?

A

Hepcidin made by liver
Downregulates iron absorption
It inhibits ferroportin-1so reduced iron in plasma

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6
Q

What may be seen on a blood film in iron deficiency?

A

Hyperchromic - decreased hb so pale cells

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7
Q

In bloods, what would be high and low in microcytic anaemia iron deficiency?

A

Low-
MCV
Serum Fe
Ferritin
BM iron

High
Transferrin
soluble transferrin receptor

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8
Q

In bloods, what would be high and low in microcytic anaemia of chronic disease?

A

Low; MCV, serum fe, transferrin,
High: ferritin

Normal: MCV, FERRITIN, sTf-R, BM iron

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9
Q

In bloods, what would be high and low in microcytic anaemia in thalassaemia trait?

A

Low; MCV, sTf-R
High; BM iron

Normal: serum Fe, transferrin, ferritin

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10
Q

In bloods, what would be high and low in microcytic anaemia sideroblastic anaemia?

A

Low: MCV
High: MCV, Serum Fe, ferritin
Normal,: transferrin, sTf-R, BM iron

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11
Q

Main causes of iron deficiency?

A

Inadequate diet
Increased requirements (growth, pregnancy)
Malabsorption
Blood loss (menstrual, GI, urinary, lung)

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12
Q

What GI investigations are there for causes of iron deficiency?

A

Drug history (NSAIDS, aspirin, bisphosphonates)
Faecal haemoglobin
Tissue transglutaminase antibody
Gastroscope

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13
Q

GI causes for iron deficiency anaemia?

A

Hookworm infections
Cancers
Coeliac and chrons
Gastritis
Peptic ulcers gastrectomy
Colitis

Etc

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14
Q

Treatment for iron deficiency?

A

Oral ferrous sulphate 3 months post Hb-normalisation OD

IV infusion if oral not work. Ferric carboxymaltose; ferric derisomaltose

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15
Q

What is folic acid and where is it found in diet?

A

In green veg, and needed for DNA synthesis
It forms deoxyuridine as a precursor for thymine dna base

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16
Q

What investigations are carried out if GI involvement is suspected?

A

Drug history (NSAIDS, aspirin, bisphosphonates)
Faecal haemoglobin
Tissue transglutaminase antibody (tTG) (for coeliac disease)
Imaging (Gastroscopy)
Stool for parasites

17
Q

How is folate absorbed into the body?

A

Absorbed in jejunum and is methylated in order to be absorbed

18
Q

What is the role of B12 in folate absorption?

A

Methyl THF is transmethylated by B12 (which forms methionine from homocysteine) to form THF to go on form DNA bases

19
Q

Where is B12 absorbed and how?

A

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

20
Q

Affects of B12 and folate deficiency?

A

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

21
Q

What is the treatment for B12 deficiency?

A

Parenteral hydroxycobalamin, 3 monthly
Can give prophylaxis after GI resection

22
Q

What is the treatment for folic acid?

A

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)

23
Q

Main causes of folate deficiency?

A

Diet
Increased utilisation (physiological/pathological)
Malabsorption
Urinary loss
Drugs (methotrexate)

24
Q

Main causes of B12 deficiency?

A

Diet
Gastric disease
Ideal disease
Infections (bacterial overgrowth in small bowel/ fish tapeworm)
Pancreatic disease
B12 destruction via nitrous oxide

25
Q

What must you check before prescribing folic acid?

A

B12 levels - folic acid can mask B12 deficiency ans can lead to sub acute combined spinal chord degeneration

Y2 Haematology (23 decks)

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