Lactose loaded hydrogen breath test

The hydrogen breath test (HBT) is used to measure hydrogen levels in the breath the patient exhales after consuming a test sugar (sucrose). Hydrogen is produced in the process of fermentation by bacteria present in the large and small intestine. In the course of certain diseases, some of the carbohydrates ingested with food are not digested and undergo fermentation.

The test involves measuring hydrogen levels in the breath the patient exhales before consuming a certain amount of sugar and then after drinking sugar dissolved in water at set intervals.

The hydrogen breath test is performed to confirm malabsorption and intolerance of lactose, which manifest through, among others, bloatedness, abdominal pain and diarrhoea after the consumption of milk and dairy products. These symptoms appear between about 30 minutes and two hours after ingestion of food containing lactose. The digestion of lactose requires the enzyme called “lactase”, which is produced by the epithelium of the small intestine. The hydrogen breath test facilitates the confirmation or exclusion of lactose intolerance.

The test is performed in adults and in children aged 10 years and older.

The test is not recommended if less than 4 weeks have passed since the patient stopped taking antibiotics. Relative contraindications include the following:

taking probiotics up to 4 weeks before the test;
radiography and colonoscopy in 4 weeks before the test;
ileostomy.

To reduce the risk of false results, 1–2 days before the test:

eat low-fibre foods;
limit your consumption of lactose (products such as lactose-free milk, cheese and vegetable drinks are allowed);
limit your consumption of fruit (less than 1 handful every 3 hours);
do not eat products that cause bloating (e.g. dry pulses);
do not drink alcohol.

How to prepare for the test?

The day before the test, avoid taking vitamins, minerals, laxatives or stool thickening products (unless they are necessary).

Do not eat anything 8–12 hours before the test. You can drink still water (unsweetened and unflavoured), but you should not drink large amounts of water in the morning on the day of the test.

On the day of the test, do not do physical activity, do not smoke, do not chew gum, do not use strong perfumes or aftershaves and do not put on lipstick.

In the morning on the day of the test, if possible, avoid taking medicines (unless it is contraindicated for medical reasons).

Before the test, brush your teeth thoroughly and rinse your mouth (do not use mouthwashes or oral rinses). Do not use denture adhesives.

As the test takes some time, you may want to take a newspaper or book to read.

In order to undergo the test, please make sure to obtain a referral from a doctor

Absolute contraindications to the test:

congenital fructose intolerance in children;
diagnosed or suspected reactive hypoglycaemia.

Relative contraindications to the test:

intake of antibiotics within the last 4 weeks;
colonoscopy within the last 4 weeks;
radiography within the last 4 weeks;
ileostomy;
acute infection.

How to prepare for the test?

Remember! A paper referral is required to perform the test.

It is necessary to refrain from taking medication such as vitamins, aspirin and laxatives for two days before the test (until the day of its performance).

On the day before the test, avoid eating vegetables which cause flatulence, such as cabbage, onions, leek, beans or pickled vegetables. DO NOT smoke cigarettes or chew gum. DO NOT drink milk or fruit juices.

12 hours prior to the test, have a meal – make sure that the meal is frugal and low in fibre – and remember not to eat anything later.

Up to 6 hours before the test, you can drink sugar-free water.

On the day of the test, you:

will be required to fast (it is acceptable to drink a glass of sugar-free water);
may take medication other than those mentioned above – as prescribed by the doctor;
will be required to thoroughly brush your teeth and tongue – right before the test (patients with dentures are advised not to use adhesive on this day).

The test lasts between 1-3 hours, depending on the indications of the doctor ordering it (an indicated factor):

fructose – 2 hours;
lactose – 2 hours;
glucose – 1 hour;
lactulose – 3 hours.

As the test takes several hours, we recommend making this time more pleasant by bringing something interesting to read.

If the result of the bioassay is >20 PPM, the test will not be performed due to the value for correct interpretation being exceeded