nutritional anaemias. iron found in most animal products – not so available from vegetarian diet...
DESCRIPTION
Vitamin B12 Vitamin B12 is found in all animal products, so nutritional deficiency is rare in all except the fussiest eaters It is not absorbed by the gut UNLESS it is bound to Intrinsic Factor (IF) which is secreted by parietal cells in the stomach lining It is then carried around the body by three transport proteins - transcobalamins 1, 2 & 3. In health the body stores several years worth of Vitamin B12 Measured in laboratory by immunoassayTRANSCRIPT
Nutritional Anaemias
Iron
Found in most animal products – not so available from vegetarian diet
Body does not easily absorb or lose iron
Deficiency state common - often subclinical complication
Iron metabolism is discussed in another presentation
Vitamin B12
Vitamin B12 is found in all animal products, so nutritional deficiency is rare in all except the fussiest eaters
It is not absorbed by the gut UNLESS it is bound to Intrinsic Factor (IF) which is secreted by parietal cells in the stomach lining
It is then carried around the body by three transport proteins - transcobalamins 1, 2 & 3.
In health the body stores several years worth of Vitamin B12
Measured in laboratory by immunoassay
Deficiency was historically investigated with the Schilling Test
•Inject a massive dose of Vitamin B12corrects deficiencyfills storesany more B12 absorbed will then be excreted
•Orally feed them Vit B12 with Co57 label and Vit B12+IF with Co58 label
•Collect urine for 24 hours
•If both isotopes are in the urine, the patient has no absorbtion problem.
•If there is only the Co58 label in the urine the patient has an underlying absorption problem
Vitamin B12
Deficiency was historically investigated with the Schilling’s Test
•Schilling’s test is no longer performed
•Feeding radio-isotopes to patients is frowned upon (!)
•Intrinsic Factor antibody assay instead nowadays
Vitamin B12
Most likely causes of deficiency:
1 Ca stomach2 Post gastrectomy state3 Auto - Immune disease4 Dietary insufficiency is very unlikely
Classic pernicious anaemia is case 3
Vitamin B12
Found in fresh fruit & vegetables, but is destroyed by cooking and storage
Body easily absorbs folate, but stores only a few months worth
Deficiency state common - often subclinical complication
Measured in laboratory by immunoassay
Folate
Two real causes of a nutritional anaemia
1 Dietary insufficiency
2 Absorption problems
Nutritional Anaemias
Dietary insufficiency
Iron is in your diet though your diet is better at holding iron than you are at absorbing it
B12 is in your diet unless strict vegan
Folate is probably in your dinner unless you don’t eat properly“tea & toast”Gran’s been boiling the sprouts
Absorption in Health
IronThe body isn’t very good at absorbing iron at the best of times.And certain foods don’t give up their iron
B12 Actively absorbed with intrinsic factor
Folate
Easily absorbed
Intestinal hurryThe best diet in the world needs time to be absorbed.
The gut function must be OKGut diseaseRadiationauto immune problemscarcinoma
Increased demand GrowthPregnancydisease (How borderline is your diet !!)
Absorption problems
Laboratory Investigations
First line test: Hb
•Is a “normal” Hb level indicative of no deficiency?
Cell size – the MCV
High
?? B12 deficiency?? Folate deficiency
Low
?? Fe deficiency
Laboratory Investigations
Specific Assays
B12FolateIron ? - why not so useful ?FerritinIron binding
Laboratory Investigations
HOMOCYSTEINE
METHIONINE
METHIONINE SYNTHASE
METHYMALONYL CoA
SUCCINYL CoA
DEOXYLADENOSYL B12
Homocysteine
METHYL THF
THF HOMOCYSTEINE
METHIONINE
METHIONINE SYNTHASE
Homocysteine
Elevated with both B12 and folate deficiency
Homocysteine
Treatments
These are anaemias of deficiency !!!!
So the treatment is obvious !!!!!!
Failure to Respond to Iron Therapy
Non Compliance Defective absorption Continuing blood loss Concurrent B12 or folate deficiency Wrong diagnosis
Failure to Respond to B12 Therapy
Non Compliance Defective absorption Concurrent iron or folate deficiency Wrong diagnosis
Failure to Respond to Folate Therapy
Non Compliance Defective absorption Concurrent iron or B12 deficiency Wrong diagnosis