How is trimethylaminuria diagnosed?

Trimethylaminuria is diagnosed with a urine test that measures the ratio of trimethylamine (the fishy-smelling chemical) to trimethylamine N-oxide (the odourless version).

If you havetrimethylaminuria, you'll have higher-than-normal levels of trimethylamine in your urine.

The urine test is carried out the day after a 'choline load'. This involves eating a suggested meal including foods high incholine, such as:

• salt-water fish
• eggs
• baked beans or soya beans
• liver

Gene testing can also be carried out, to look for any genetic changes in the FMO3 gene. This means avoiding:

• milk from wheat-fed cows
• eggs
• liver
• kidney
• peas
• beans
• peanuts
• soy products
• Brussels sprouts
• broccoli
• cabbage
• cauliflower
• seafood (fish and crustaceans), although freshwater fish can be eaten
• lecithin and lecithin-containing fish oil supplements

However, if you're pregnant or planning a pregnancy, contact yourdietitian or GPbefore restricting your diet.

Medication

Takinglow doses of Penicillin can reduce the amount of bacteria in your gut and suppress the production of trimethylamine. However, to avoid antibiotic resistance, these should only beused now and again, or alternated every two weeks.

Laxatives can speed up the passage of food through your bowel so less trimethylamine is produced in your gut.

You may also be able to decrease the concentration of trimethylamine in your urine by taking supplements such as:

• 750 milligrams (mg) of charcoal twice daily for 10 days
• 60mg copper chlorophyllin three times a day for three weeks
• riboflavin ( vitamin B2 ) supplements to enhance any FMO3 enzyme activity

Always seek the advice of your doctor before trying any of the above medications and supplements.

Other lifestyle measures

It's a good idea to avoid anything that causes you to sweat excessively, such as intense exercise and stress. To help, try easy exercises and learn how to cope with stress .

Use soap and shampoos with a pH between 5.5 and 6.5. These help to remove traces of trimethylamine from your skin and hair.

Counselling

Trimethylaminuria can be very upsetting, potentially affecting your personal life and career. Depression and social isolation are common.

Counselling may help you cope with any depression and other psychological symptoms. For more information, visit our pages on how to get help for stress, anxiety and depression .

Genetic counselling may help you understand how you developed the condition and the risks of passing it on to any children you have.