Lactose H2 Breath Test

The lactose H2 breath test (H2 breath test; H2 exhalation breath test; hydrogen breath test; hydrogen exhalation test) is a diagnostic test method for detecting lactose malabsorption, which is the impaired absorption of lactose (milk sugar) from the small intestine.

Indications (areas of application)

The lactosehydrogen breath test is a highly sensitive procedure to detect whether lactose malabsorption is present.

Before the examination

No antibiotics should have been taken and no colonoscopy (colonoscopy) should have been performed in the 4 weeks prior to the test.

The patient should not eat a high-carbohydrate, high-fiber diet the day before the examination. From the evening before the examination, patients should not eat, drink – except mineral water – or smoke. Smokers exhale carbon monoxide, which can activate the test device’s hydrogen sensor, producing false results.

On the morning of the examination day, do not eat or drink anything, neither eat sweets nor chew gum. In addition, teeth should not be brushed and mouthwash or mouth spray should not be used.

No exercise should be performed immediately before the test; likewise, no physical activity should be performed during the test.

The procedure

In this breath test, the patient’s exhaled air is measured for hydrogen concentration before ingestion and every ten minutes (up to a maximum of four hours) after ingestion of a test sugar (200 ml lactose solution/50 g lactose; children 2 g/kg bw).The principle of the test is that various disorders in the small intestine that prevent the absorption of lactose result in increased production of hydrogen, which passes through the intestinal wall into the circulation and thus into the lungs. There, the hydrogen is exhaled.The examiner can then identify increased hydrogen exhalation as a pathological finding.

During the H2 breath test for fructose, it is recommended to blow every 10-15 minutes for the first 60 minutes, then every 30 minutes.

Hydrogen concentration readings are reported in parts per million (ppm).

Duration of the test* : 2 hours

Interpretation

Basal value is the initial value measured before drinking the test solution.

Subsequent values are measured every 10 minutes after ingestion of the test substance. If one of the values – or two consecutive values – rises above 20 ppm above the basal value, then the test is considered positive.

* If, after two hours, the readings have risen no more than 10-20 ppm above the basal level, the test should be extended to 4 hours.