Lactose Intolerance: a highly accurate alternative to the hydrogen breath test
What is lactose intolerance?
Lactose intolerance (LI), or hypolactasia, is a common digestive problem whereby the body cannot digest lactose, the sugar found in milk and dairy products. It is caused by a shortage of the enzyme lactase in the small intestine, which breaks milk sugar into glucose and galactose to then be absorbed into the bloodstream. Prevalence of this condition is estimated to be at least 5%, however although lactase activity begins to decrease after weaning, roughly a third of the adult population worldwide retains the ability to digest lactose.
LI may be due to primary hypolactasia, or secondary causes of lactose maldigestion, including coeliac disease, infectious enteritis or Crohn’s disease. Congenital lactase deficiency can also be found.
Symptoms of LI include nausea, flatulence, abdominal bloating/cramps/pain and diarrhoea. As these are such generic symptoms, often LI is undiagnosed and therefore may be left untreated for years.
How is it diagnosed?
The gold standard method for lactase determination is the biochemical disaccharide test, a homogenised biopsy test. However, this is a time consuming and expensive test that is now rarely used. More commonly used is the hydrogen breath test, whereby a lactose solution is ingested, and levels of hydrogen and methane are then measured in the breath – these gases being produced, along with carbon dioxide, when undigested lactose is fermented by the intestinal flora. The gases are absorbed and eliminated by the lungs, but can also cause the bloating, flatulence, abdominal pain and diarrhoea seen in LI. In addition to being time consuming, the reliability of the breath test can be affected by use of antibiotics, colonic pH or adaptation of the intestinal flora arising from continuous lactose exposure. False negatives can also occur in up to 20% of patients with lactose malabsorption.
Another option is using an oral lactose tolerance test for diagnosis, which also involves the ingestion of lactose solution, but in this case measures the subsequent increase in blood glucose levels. Like the breath test, this is also time consuming, with the possibility of results being affected by environmental factors.
BIOHIT Lactose Intolerance Quick Test
The Lactose Intolerance Quick Test (LIQT) from BIOHIT is a test for lactase activity performed on a biopsy collected from the D2 region of the duodenum (post duodenal bulb), as part of gastroscopy. It is a simple test which is performed immediately, with the addition of three ready-to-use reagents giving a measurement of the amount of lactase enzyme activity, revealed by a colour change, in a maximum of 20 minutes. No instruments are required for the test, and results are easily visually interpreted.
Simple test procedure
- Place biopsy into the well. Add two drops of reagent 1, shake the plate and leave for 15 minutes.
- Add one drop of reagent 2 and two drops of reagent 3. Shake the plate and leave for 5 minutes.
- Read the result against the colour chart.
The semi-quantitative results indicate; severe hypolactasia/alactasia, mild hypolactasia, or normolactasia.
- Quick & easy diagnosis of a high prevalence condition – LIQT provides a direct and highly specific measure of lactase activity via a quick and easy to use method requiring no specialised training or equipment. Results are available in only 20 minutes, enabling testing and reporting during one visit.
- Greater accuracy than alternative methods – compared to the lactose breath test, LIQT is more sensitive[1] and also more accurate in predicting clinical response to a lactose-free diet[2]. Sensitivity of LIQT is 95%, with a specificity of 100%[3].
- High clinical utility – rule-out LI in irritable bowel syndrome (IBS) and functional dyspepsia, identify primary, secondary, congenital and familial lactase deficiency, assess the degree of lactase deficiency in coeliac disease, and exclude or confirm lactase deficiency as a cause of symptoms.
- Increased diagnostic yield from gastroscopy – the LIQT is cost effective in patients who are undergoing gastroscopy. Most patients who receive an inconclusive hydrogen breath test would ultimately undergo endoscopy anyway.
References:
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Ojetti V, La Mura R et al. Dig Dis Sci. 2008; 53(6): 1589-92
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Jolanda F, Parodi F et al. Poster presentation at DDW 2009; S2067
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Kuokkanen M, Myllyniemi M et al. Endoscopy 2006; 38: 708-712
