Can laboratory tests confirm lactose intolerance?
Mar 13, 2025
Source: Cainiu Health
Dr. Shen Yonghua
Introduction
In general, laboratory tests can confirm lactose intolerance, and if necessary, should be performed under a doctor's guidance. Lactose intolerance is caused by a deficiency or reduced activity of lactase in the body, leading to an inability to effectively break down lactose, which in turn triggers a series of gastrointestinal symptoms. In the laboratory, lactose levels in the blood and galactose levels in the urine can be measured.
In general, laboratory tests can confirm lactose intolerance, and if necessary, should be conducted under the guidance of a doctor. Specific analyses are as follows:
Lactose intolerance is caused by a deficiency or reduced activity of lactase in the body, leading to an inability to effectively break down lactose, which in turn triggers a series of digestive system symptoms. In laboratories, the digestion and absorption of lactose can be assessed by measuring lactose levels in the blood and galactose or glucose levels in the urine. For example, during a lactose tolerance test, a doctor administers a certain amount of lactose to the patient and subsequently measures blood glucose levels. If the patient is lactose intolerant, their blood glucose level will not rise significantly. Additionally, reducing sugars in the urine can also be tested; after consuming lactose, patients with lactose intolerance will show a significant increase in these reducing sugars in their urine.
Gene testing is also an effective method for diagnosing lactose intolerance. Some types of lactose intolerance, such as congenital lactase deficiency, are caused by genetic defects. Genetic testing can accurately identify whether there are gene mutations that cause lactase deficiency, thereby confirming the diagnosis of lactose intolerance. This method is suitable for patients with typical symptoms but negative results from routine biochemical tests, or for those needing to determine the genetic type of lactose intolerance.
Patients with lactose intolerance should avoid or limit the intake of foods high in lactose, such as milk, cheese, ice cream, and other dairy products.
