Lactose Intolerance Quick Test (BIOHIT)

What is lactose intolerance?

Lactose intolerance occurs when an individual is unable to digest lactose. This can occur when an individual does not express sufficient lactase enzyme to cope with the amount of lactose ingested, or as a result of intestinal injury or atrophy due to other diseases or events.

What are the symptoms of lactose intolerance?

Symptoms of lactose intolerance are broad and can be very non-specific, varying among individuals. Some individuals report systemic symptoms but the most common symptoms include:

• Bloating
• Diarrhoea
• Gas/excess wind
• Abdominal cramps or pains
• Nausea

Symptoms usually occur within a few hours of consuming lactose-containing foods or beverages.

How does the Lactose Intolerance Quick Test work?

The Lactose Intolerance Quick Test detects the amount of lactase enzyme activity in a duodenal biopsy sample. A lactose substrate is added to the biopsy in a small test plate which is hydrolysed by any lactase present in the specimen. The product of this enzymatic reaction is detected by a colour change that is proportional to the amount of lactase in the biopsy sample. If there is no colour change, it indicates severe lactase deficiency (alactasia or severe hypolactasia). Conversely if a colour develops it indicates the presence of lactase.

How accurate is the Lactose Intolerance Quick Test?

The Lactose Intolerance Quick Test is based on the gold standard biochemical disaccharidase test which directly measures lactase activity in biopsy specimens. Compared to the biochemical disaccharidase test LIQT has a sensitivity and specificity of 95% and 100% respectively.

Which patient groups does the LIQT apply to?

The Lactose Intolerance Quick Test can be used to identify lactase deficiency in adults and children undergoing gastroscopy. It can be used in cases where lactose intolerance is suspected or where abdominal symptoms indicate the need for testing.

What other tests are available for lactose intolerance?

Lactose intolerance can be investigated through various methods, each with their own merits and drawbacks:

1. Lactose Tolerance Test: Which involves fasting overnight and then drinking a liquid that contains a high amount of lactose. Blood samples are then taken at intervals to measure the body’s response to digesting lactose based on changes in blood glucose levels. An increase in blood glucose demonstrates lactose digestion.
2. Hydrogen Breath Test: Following an overnight fast the patient drinks a concentrated lactose solution. Breath samples are then analysed for the presence of hydrogen. In cases of lactose intolerance bacteria in the colon will ferment lactose, leading to the release of hydrogen.
3. Stool Acidity Test: This test is often used for infants and young children. It measures the acidity of stool after consuming lactose. Undigested lactose in the colon can make the stool more acidic.
4. Genetic Testing: Genetic tests can determine if you have genetic variants associated with lactose intolerance or more specifically lactase persistence, such as the C/T13910 polymorphism test, but they may not necessarily indicate the presence or severity of symptoms.
5. Elimination Diet: Some people choose to identify lactose intolerance by eliminating dairy products from their diet and then reintroducing them to see if symptoms recur.

How does the Lactose Intolerance Quick Test compare to the hydrogen breath test?

In a study comparing the Lactose Intolerance Quick Test to the hydrogen breath test (H2BT) the concordance was 81%. However, the LIQT appears to correctly identify more cases of adult type hypolactasia in a subgroup of patients who have low H2 production using H2BT (false negatives) and when methane (CH4) production is taken into account in these patients to maximise the sensitivity using a combined methane and hydrogen breath test the concordance increased to 96%.

What causes lactose intolerance?

If a patient presents with symptoms of lactose intolerance it is important to understand the patient’s medical and family history. Lactose intolerance symptoms usually develop gradually over time as the individual ages – adult type hypolactasia is actually a normal phenomenon that begins to occur post-weaning. However, around 1/3 of individuals retain the ability to digest lactose throughout their life through prolonged lactase expression. Lactose intolerance is also more likely to occur in certain populations with a wide distribution of disease prevalence across the globe.

Other factors can cause lactose intolerance too:

• Infection or illness that affects the digestive system (e.g. Crohn’s disease or gastroenteritis).
• Surgery or injury to the small intestine.
• Certain medications or treatments that affect lactase production.
• Aging, as lactase production tends to decrease with age in some individuals.

It’s important to note that lactose intolerance can also be a lifelong condition, and some people may have a genetic predisposition to it from birth. If you suspect your patient has lactose intolerance or experiences symptoms, proper diagnosis and management is key.