Test for Lactose Intolerance

A case

Jane M. has been suffering from recurring digestion problems for years. Repeatedly she gets diarrhoea, sometimes accompanied by vertigo or nausea. Then she has periods when she feels fine again, but all of a sudden her problems can reoccur. Her diarrhoea attacks restrict her in her daily activities and she feels worse each year. After many years she hears about milk intolerance and simply leaves out all dairy products. This improves her symptoms to a certain degree. A test for lactose intolerance was positive in Jane’s case. After she had eliminated all products containing lactose from her diet her symptoms disappeared completely.

Lactose and Lactase

People with lactose intolerance either cannot digest lactose (milk sugar) from food sources properly or not at all. This is caused by a lack of the enzyme lactase. Lactose is a disaccharide, which is composed of the monosaccharides galactose and glucose. Lactose represents the most important carbohydrate in the milk of mammals and the respective concentration depends on the species. Lactose is of crucial importance in nutrition, especially for babies.

Lactose tolerance with age

After the age of about three, however, a certain percentage of people get lactose intolerant.

Diagnostics:

In former times lactose intolerance was diagnosed by a lactose tolerance test. Before and after a provocation meal of 50g lactose (in children 2 g/kg, maximum of 50g) blood was taken to measure blood glucose. If there was an increase of blood glucose of over 20 mg/dl in two hours, it was assumed that sufficient lactose had been split and absorbed. Today this lactose ntolerance test has been widely replaced by the H2 breath test in which the hydrogen concentration is measured before and after a provocation meal with 25g lactose (in children 1g/kg, maximum 25g). If there is an increase in H2 concentration by more than 20 ppm above the basal reading, it can be assumed that enough lactose has been metabolised. Both methods can lead to severe symptoms in lactose intolerant patients. A gene test is a new detection method. Only recently the genetic cause for the lactose intolerance was discovered. At the location 13910 before the lactase gene (LCT) there is a polymorphism, which determines the quantity of lactase produced. By testing the LCT genotype the genetic disposition can be determined.

LCT-Genotype Importance

• LCT-13910 TT No genetic lactose intolerance (approx. 40 % of the population)
• LCT-13910 TC: Heterozygote symptom carrier, no increased risk of a primary lactose intolerance (approx. 45 % of the population)
• LCT-13910 CC: Genetic disposition for lactose intolerance (approx. 15 % of the population)

SAMPLE REQUIREMENTS: Since May 2024 the sample requirement is a blood sample which is unfortunately not possible any more by mailing samples.

Find out more about Lactose and Lactase HERE.