In the lactose tolerance test, what substance is primarily tested for?

In the lactose tolerance test, the primary substance that is measured is glucose. This test is designed to assess how well the body can digest lactose, which is a sugar found in milk and dairy products. When lactose is consumed, it is broken down by the enzyme lactase into its component sugars, glucose, and galactose.

If a person has sufficient lactase activity, lactose will be effectively digested and absorbed into the bloodstream, resulting in an increase in blood glucose levels. Therefore, the test measures the increase in glucose levels after lactose ingestion to determine if there is an issue with lactose digestion. If glucose levels do not rise adequately, this suggests that lactose is not being broken down properly, indicating lactose intolerance.

Measuring glucose rather than directly measuring lactose itself is key in diagnosing lactose intolerance, since glucose levels reflect the efficacy of lactose digestion and absorption. Other options, such as insulin and galactose, are not the primary focus in this specific context of lactose metabolism.