MMA Test - Urine or Blood Best?

[arcticsun]

Hi everyone. I have come over from thyroid uk, as I am desperately searching for an answer to my mum's deteriorating health. She has graves disease, confirmed with positive antibodies test in 2015. She is now house-bound and has many symptoms of b12 deficiency along with an in range, but low, Active b12 blood draw last week.

57.9 (37.5-188 pmol/L)

May I ask to draw on some of your knowledge?

For MMA testing, which is deemed better (if any), blood test or urine test? When I ask which is 'better' I suppose I mean both more accurate, and more acceptable to the NHS? I realise these two don't always marry up!

Thanks for any help!

[fbirder]

Acceptable to the NHS? That would be the blood test. The urine test isn't available on the NHS.

If done properly then the urine test may be better. That's because raised levels of MMA can have many causes. One of these is a kidney problem, So, if you do have raised MMA the doctor should check on kidney function - which is best done with a urine test. So a urinary MMA test can use the same sample.

But most places aren't going to test for kidney function.

[arcticsun in reply to fbirder]

Thank you for the response fbirder,

May I ask a couple more questions if you have time?

1. Is the MMA test a conclusive test? If the results don't support b12 deficiency does that completely rule it out as a cause of her symptoms?

2. Do you know if antibody testing in relation to b12 deficiency should also be done pre b12 injections also, or are these results unaffected by b12 dosing?

Thanks you so much!

[fbirder in reply to arcticsun]

1. It’s my strong belief that B12 is involved in something other than the two known processes. Before I started treating myself with frequent injections I had terrible symptoms, but high serum B12 and normal MMA. So I don’t think that normal MMA can rule out B12 as a cause. But most doctors would.

2. The anti-IF antibody test can get affected by high levels of serum B12, depending on how old the method is that they use. Modern tests shouldn’t be affected at all, but advice is to leave a couple of weeks after an injection before being tested.