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Flashcards in B 12 Deck (25)
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1
Q

Holotranscobalamin - what is

A

Transcobolamin bound to b12
Active
25% b12

2
Q

What is haptocorrin

A

Glycoproteins binds 75% b12

Holohaptocorrin

3
Q

What Changes total B 12

A

Change in binding protein

4
Q

Metabolic function of b12

A

Last step in fatty acid digestion-
2 methylmalonyl A to succinyl co A
If this doesn’t happen in mitochondria- mma leaks out
2- making methionine w homocysteine- this will also be elevated in folate def

5
Q

Genetic haptocorrin def

A

Low total b12 bug normal tissue b12(Holo TC)
No clinical manifestation b12
Found in 15% w low total b12

6
Q

Clinical indications for b12 testing

A
Macrocytic anaemia
Anaemia of chronic kidney diseases
Cognitive de
Dementia
Polyneuropathy
Chronic fatigue syndrome
7
Q

What is good negative predictor of b12 def

A

Normal mma/homocysteine

8
Q

Plasma homocysteine limitations

A
Non fasting
Ageing/rénal impairment 
Smoking, coffee wine
Low folate/Vit B6
Hyper proliferation d/o
Genetic defect

High npv

9
Q

Mla limitations

A

Elderly
Rénal failure
Urine mma more influenced by good than plasma
Hypocolaemia

10
Q

Anti if ab

A

Near 100% spec for PA

50-70% sens

11
Q

Transferrin sat < 15%

A

Latent iron deficiency

12
Q

Timing iron studies

A

Early am fast

Because dietary iron can inc iron- this is used in calculation of t sat gives false result

13
Q

sTFr in fe def

A

Increased

Not affected by infection

14
Q

sTFr in pgy

A

Increased due to inc stimulation of eryhtropoeisis and inc iron requirements by iron dependant cell proliferation
Can be used in pgy
Not affected by post partum inflammation like ferritin
Useful I’m unclear situations in pgy

15
Q

McV in pgy

A

Falsely high due to inc erythropoeisis so not reliable for fe def

16
Q

TIBC in pgy

A

Raised

17
Q

What can lower tibc

A
Infl 
Chronic infxn 
Malignancy 
Liver disease 
Nephrotic syndrome 
Malnutrition
18
Q

sTFr

A

86% sen 75% spec
Not standardised
Is a truncated fragment of membrane receptor

19
Q

Hepcidin in iron homeostasis

A

Inhibits iron entry into plasma from gut, macrophages
Deficiency causes iron overload
Interacts w ferroportin to control iron flow- causes it to internalise and degrade

20
Q

Iron excess causes ? Hepcidin

A

Inc production

21
Q

Iron

A

Colorimetric assay

Ferrizyme binds to iron and get colour change

22
Q

False high iron

A

Haemolysis

23
Q

Transferrin assay

A

Immunoturbidometric
Human t ferrin forms precipitate w antiserum which is determined turbidemetrically
Measure might- more précipitante there is less light so inv proportional to ferritin

24
Q

Interférence w ferritin

A

High level paraprotein

Biotin

25
Q

Ferritin assay

A

Colourimetric sandwich assay

Solid phase