- Published on Wednesday, 04 April 2012 15:38
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Principal Clinical Scientist
Dept. Clinical Chemistry
Sheffield Children's Hospital
Thanks very much for taking the time to answer these questions. I have had loads of question through via email and I am certain your help will be greatly appreciated by everyone.
Can you briefly explain for our readers your background and experience in testing for tmau?
As an NHS laboratory scientist I’ve been involved in the diagnosis of metabolic disorders at Sheffield Children’s Hospital for over 20 years. The techniques we use for such work can often be employed in the development of new tests in the field and when an existing TMA service in London closed in the late nineties I managed to adapt the use of an instrument known as a mass spectrometer to detect TMA. By the end of 1997 I had developed a method to give reliable measurements of TMA and TMA-oxide so the service was started. Since then we have modified and improved the test which now runs on a more modern instrument with a greater capacity. To date we have analysed more than 1,300 urine samples for TMA and TMA-oxide.
Are there any figures, both worldwide and in the UK for the number of people who have been diagnosed with TMAU?
It is unlikely that an exact figure will be available for worldwide diagnoses. TMAU will encompass both primary and secondary forms so getting figures for patients with increased urinary TMA concentrations worldwide would involve surveying all the centres who have ever tested for TMAU. DNA analysis gives the ultimate confirmation of primary TMAU (FMO3 deficiency) so perhaps numbers of DNA-confirmed TMAU1 patients may eventually be collated.
How many people have you tested in your lab and of those how many have been diagnosed with TMAU 1 and TMAU 2?
Without DNA analysis, it is impossible to confirm urine TMA results which tend to indicate TMAU1, but from 1997 to 2009 we found results indicating TMAU in 379 adults and children who complained of an odour. Using increased TMA/TMA-oxide data as a possible indicator of TMAU1 approximately 67% fell into this category. However only 27 of these patients have since been followed up by DNA analysis with just 9 giving confirmation of FMO3 deficiency.
With the recent media exposure have you seen a recent increase in test requests?
Certainly, since the 2007 BBC3 documentary we have seen a significant increase in requesting. In 2006 we analysed less than 100 samples, but for 2008 and 2009 that figure has more than doubled. Since the Embarrassing Bodies programme on Channel 4 and then the BBC’s One Show we have noticed a dramatic rise and we are now running 21 tests per week (our absolute capacity) to keep pace with requests.
Are there other Lab’s in the UK testing for TMAU? (We have had reports on the forum of labs testing for the wrong chemical)
As far as I know, there is no other lab offering a routine service.
Are you aware of any other Labs doing testing outside the UK? (We have had enquiries from places such as Brazil and India)
Yes, there are several centres including laboratories in Holland, Germany, Australia, Canada and the USA.
Are the testing procedures /protocols at the labs in the UK and worldwide all the same?
No, procedures and techniques and data vary between centres, as is the case with almost all diagnostic tests. Most TMA measurements are made using mass spectrometry (as in our lab), although there are other techniques used such as magnetic resonance spectroscopy.
Can you briefly outline the testing procedure?
In our laboratory each urine sample is tested twice for TMA and twice for TMA-oxide (‘total TMA’). The TMA-oxide measurement is done following a chemical process to convert TMA-oxide to TMA which is then measured by the same method as the ‘free’ TMA. We add to each test sample an accurate amount of a special synthetic TMA which has been made using ‘heavy’ hydrogens. This means we can use a mass spectrometer to obtain a ratio of urinary TMA to ‘heavy’ TMA and compare that to known amounts of TMA to achieve a final result.
The actual instrument we use is known as a gas chromatograph - mass spectrometer or GCMS for short. The samples are treated with strong alkali before heating in an oven then the heated vapour above the sample is injected into the GCMS for analysis. Each batch (which also includes quality control samples and known amounts of TMA and TMA-oxide) is injected 3 times for the final result - taking 48 hours in total.
Is all testing done via the NHS or can you do private tests as well?
We receive most of our samples from NHS hospitals with less than 10% from private hospitals and laboratories in the UK and a few per year from overseas.
Would you recommend doing a pre choline load test followed by a post choline load test?
When an odour is intermittent it is important to collect a sample when the odour is at its strongest. Sometimes this can be in response to choline in the diet, so to create those conditions a load may be necessary. It really depends on the circumstances of the individual. If an odour is a constant problem then a load shouldn’t be necessary. Some women have an odour problem around the time of their period, in which case this is the time to collect a sample and a choline load may not be necessary.
In general, a meal of say 2 eggs and 400g of beans on toast should be a good choline load for a collection a few hours afterwards.
Can you give some general guidance on interpreting the test result numbers in respect of what this means in terms of the severity of TMAU?
This is a very difficult question. There have been studies of severity of odour related to DNA mutation in the FMO3 gene, but offering guidance on urinary TMA concentrations and degree of odour may be misleading. The issue is whether urinary TMA levels reflect levels in sweat and on the breath of TMAU patients. Also the degree to which people can smell TMA seems to be very variable. We have known of a case when an odour was a problem when urinary TMA was more than 300 (normal is less than 11) but after treatment no odour could be detected by the patient although they still had a high urinary TMA value of more than 50. This contrasts with patients whose values were as low as 14 when they complained of an odour.
Factors such as circulating levels, excretion and sweat rates will play a part in how much of a TMA odour is generated and these will certainly vary.
Severe TMAU may be indicated by very high urinary TMA (eg over 1,000) but TMA amounts released in sweat possibly vary too much for an accurate severity scale of odour using urinary TMA for the majority of TMAU patients.
What are the highest TMA figures you have tested for someone with TMAU?
We have measured values of more than 10,000 in two patients.
Can people get referred to you by their GP for testing after undergoing different antibiotic therapies to determine what works best for them – do you think this is a good idea?
I would always advise a follow-up test following any therapy. I am routinely contacted by GPs about patients who have increased urinary TMA and want to try a course of antibiotics. Naturally the first test for the antibiotic therapy is whether the odour has reduced, but this may depend on circumstances such as who is able to smell the odour (of course, it may not be the TMAU patient who can smell their TMA odour).
I would still recommend the monitoring of urinary TMA to help both patient and GP assess what is working best for their condition.
In respect of antibiotic treatment; is this equally as effective in suppressing symptoms for both TMAU 1 and TMAU 2?
This depends on many factors for both TMAU1 and TMAU2. Intestinal bacteria are a large part of our metabolic make-up. Types of bacteria vary between individuals with up to 1,000 different species colonising our intestinal tracts. Some may dominate and become firmly established. If in excess, TMA producing species can give an odour which may take one course or many courses of antibiotics to eradicate.
TMAU1 patients (i.e. FMO3 deficient) will benefit from periodic antibiotics to reduce intestinal TMA production and those mild or ‘carriers’ for the mutant FMO3 gene will be possibly be able to time their antibiotic courses if they coincide with circumstances where they may expect the odour to return (eg menstrual periods).
I f someone has TMAU 2 is it possible for antibiotics to eradicate the condition completely?
Yes – we have known of a patient in whom the odour was eliminated with a single course of metronidazole. Further doses (and possibly different antibiotics) may be required for some TMAU2 patients, although long-term antibiotic use needs to be carefully controlled to avoid antibiotic resistance.
Have you any general guidelines for alternating antibiotics (or not), which ones to use and also dosage / frequency.
As a scientist and not a doctor I would prefer to leave that question for medical colleagues such as Robin Lachmann.
What is you take on the use of copper chlorophyllin charcoal and riboflavin
Adsorbants such as Nullo, Chlorofresh, charcoal and Champex (Agaricus bisporous) are worth trying, although anecdotal reports suggest that these products work for some people but not everyone.
Riboflavin is becoming more widespread in its use and has had some dramatic effects in reducing urinary TMA in our experience. It probably works by enhancing FMO3 activity so may be effective as part of a general therapeutic approach or even on its own. 100mg per day of riboflavin may not work for everyone but monitoring TMA should show any effect after a few weeks.
Reading the forums reveals that many people have difficulty convincing their GP of the existence of TMAU and even then the procedure for getting tested seems unclear for both the patient and the GP – Have you any advice on this?
If the GP has problems recognising the existence of TMAU then, apart from looking it up online (OMIM is a good scientific source) then I would be happy to supply information or take a phone call and discuss it. The procedure may be a little difficult for GPs as they don’t always have immediate access to 24 hour collection bottles and hydrochloric acid. Their local hospital should be able to deal with this and GPs should be able to arrange a 24 hour acidified sample by talking to the hospital’s clinical chemistry or chemical pathology lab. Sometimes a GP will prefer to arrange a referral to either a gastroenterologist, metabolic physician or a dermatologist at a hospital which can deal more easily with the investigation and arranging to send the sample to us at Sheffield Children’s.
Either way I’m happy to talk to GPs if they have concerns.
Specific Questions from individual forum users: (I think you may well have answered parts of these questions in the preceding answers)
I am about to hand in a urine sample to a local biochemistry lab in Glasgow.
Do you know if there are labs other than yours, in the UK, successfully diagnosing TMAU (and differentiating between types 1 and 2)?
None that I know of.
Do other labs know to refer to you for advice on testing or is there a standard protocol they would automatically know to access?
NHS laboratories and anyone else can access our TMA testing information by checking a service known as Assay Finder, which we all use for looking up who does what test and whether there are special conditions which apply to samples, storage transport etc.
Would it be possible for there to be a problem with the collection / handling / processing of the sample, which resulted in a false negative? And would this be obvious from the result?
It is unlikely that a false negative will be generated by incorrect sample collection and handling. There are, however, potential problems that can arise if samples are not acidified before posting. The hydrochloric acid stabilises the TMA as its hydrochloride salt and also prevents bacterial growth within the sample which can generate TMA and therefore potentially give a false positive result. Although the lack of acidification will be noted when the sample arrives with us and possibly a delay in transit may be noticed, it is virtually impossible to know how much a sample result may have been affected by these conditions. In this case a repeat sample is the only answer.
I thought I should mention that I also suffer from Chronic Inflammatory Demyelenating Polyneuropathy, for which, among other things, I receive six weekly infusions of Immunoglobulin. I note that TMAU is a genetic condition, and since I know of no such occurrence within my family, I wondered if it is possible that this condition could have been contracted via the Immunoglobulin infusion
TMAU can be secondarily caused by diseases that affect the liver or kidneys as well as intestinal bacterial overgrowth but I wouldn’t want to speculate about the side - effects of immunoglobulin infusion in any individual.
I wondered if all Trimethylene analysis is done by you. My first 24 hour urine specimen was sent to our local hospital laboratory, and was tested for all the wrong chemicals. I discussed this with my GP, and he said he would ensure that my second specimen would be clearly labelled, but he was unsure about what would happen next. He said he is not familiar with TMAU, in fact, it was only on my reference to this website that he took action.
I’m not aware of any other laboratory offering a service at present (according to Assay Finder).
If it transpires that the second specimen has suffered the same fate as the first, would it be possible for me to ask my GP to have it sent to you directly, or does my out of the way location preclude this?
We offer a national and international service and I’d be happy to talk to your GP and make any arrangements necessary.
Finally Dr Manning has you any advice or words of encouragements to anyone who has TMAU.
Even though modern medicine has enabled the diagnosis TMAU since 1970, there is a much greater awareness of this condition now than just 10 years ago. There are many new approaches to diagnosis (such as DNA analysis) and therapy (antibiotics and riboflavin) that should give hope to anyone suffering from this condition. I’m sure people suffering with medical malodour will be taken more seriously by healthcare professionals as a result of publicity and understanding of TMAU especially with the help of online forums and support groups.
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