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