Comment on the NEW UK TMAU Test (Sheffield)

NEW TEST

In early March the 'Sheffield TMAU Test Team' kindly gave a lecture at the UCL Adult Metabolic Unit in London to a group of TMAU patients.

Below is an abridged version of the lecture

Sheffield NEW TMAU Test lecture slides (hosted on SCH site)

The main 'changes' seems to be :
Almost no TMAU2 cases (this used to be a very large group).
A large amount that had no detectable TMA (this is a new category).
A big drop in TMAU1 cases (?)

Here's some thoughts on the old/new test.  The views may be inaccurate.
Maybe over time things will become clearer.

Interference :
A main reason given for the 'changes' is that the old test was prone to interference.
In effect saying there were many false 'positives'.
This may be true or not, but for some reason IMHO the old test was better at spotting the METBO smell disorder most people have.
Perhaps the incorrectly detected volatiles were a better measure of the disorder the person has.
Who knows ?

OLD TEST

Liberal (and fair) new ref range :
The new test has what could be termed a 'very liberal reference range' (TMAU1 = <94%).
The old test was very conservative. (TMAU1 = < 79%).
With the new test ref-range, old test results would maybe have been 70% positives ... which I think is likely in a group who identify with systemic body odor.
Instead, the new test gives 16% positives.

TMA and TMAO levels
New TMA levels are way lower than the old test levels :
TMAO seems slightly lower but not much,
but TMA levels in general seem way lower on average.

You'd think there would be many more TMAU1's but it's not the case.
Old test 'positive' rate : around 33%
New test : around 16%

I accept that the new test may be more 'precise' at detecting TMA, but have long guessed most metBO cases are not based around TMA anyway.
TMA should still be an excellent biomarker of FMO3 function, but I have doubts too.

For some reason I think the new test now misses the vast majority of FMO3 smellies, the 'mild genetic transients'.

New Sheffield ref ranges.

TMA:  < 7.7 µmol/mmol creatinine
TMANO: < 119µmol/mmol creatinine
% N-oxidation: > 90-94%

Old Sheffield ref ranges.

TMA:  2.5 - 10 µmol/mmol creatinine
TMANO: 17 - 147 µmol/mmol creatinine
% N-oxidation: > 79%

TMAU2
A new explanation for the lack of TMAU2's is that in fact most might be 'mild genetic TMAU1's'.
I tend to agree with this theory.
I don't think 'normals' ever fall into the 'zone'.

New big group of 'non-detectable TMA' cases
Of 722 tests, 147 had no detectable TMA level.
The old test thought that a normal human would have at least >2.5umol TMA.
I tend to agree with the old test. Humans probably have some TMA in them.

Old and New test can't be compared
It's been said the old and new test can't be compared.
Both use Gas Chromatography/Mass Spectrometry and have the same scale for ref range.
So to me they are directly comparable.

What can be done to change the UK system ?

TMAU / metBO people are poorly served by their societies.
It will be by miles the biggest 'rare disorder' (i.e. not rare).
Any Health Service test labs that offer the TMAU test regard it as very charitable and to question is an insult.
Their set-ups suit the department workers.

Any change to an acceptable minimum standard will have to come from politicians.
Examples :
People can write to their MPs
e.g.
Let people test direct and self-pay for the TMAU test.
If only one lab tests, it is the national lab, and has a  responsibility to do more ... e.g. have a website and contact point.

Perhaps if anyone lives in the Sheffield area they can contact their politician to insist of minimum levels of help.
Ultimately the test should be done at all NHS 'rare disorder' test labs.     

TMAU / MetBO people worldwide should always remember our current help is below a minimum standard.   

That said, thank you to Sheffield CH for the slides and lecture.

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By sysbodyodor

campaign, main points, tmau, TMAU stats, tmau test

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