Lactose Tolerance Test

A lactose tolerance test (LTT) is performed in cases of suspected lactose (the form of sugar found in dairy foods) intolerance. The LTT assesses whether there is a deficiency of lactase (the enzyme needed to absorb lactose) by seeing if blood sugar levels rise after lactose has been eaten. The test is done on an empty stomach. First a blood sample is taken, then you are given some lactose. Thereafter blood samples are taken every half an hour for 2 hours and blood sugar is measured. As dairy food is important in a balanced diet, especially in children, the LTT test is useful for ruling out lactose intolerance.

What is it?
The lactose tolerance test (LTT) assesses your body?s ability to absorb lactose.

LTT may be performed in your doctor’s rooms, a clinic, or in hospital. It takes 2 hours to complete the test.

Why is it done?
Lactose is the form of sugar found in dairy foods. Some people are deficient in the enzyme required (lactase) to absorb lactose. The LTT can assess this by determining if blood sugar levels rise following ingestion of lactose ? blood sugar levels will only rise if lactose has been absorbed.

The LTT is therefore done in cases of suspected lactose/dairy intolerance.

What happens?

Before – how to prepare
You need to fast (eat and drink nothing) for 8 hours before the test.

During – how the test is done
An initial (fasting) blood specimen is taken and you are then given 100g of lactose, orally. Blood specimens are taken every 30 minutes over a 2-hour period and the blood sugar is measured.

After the test
You will have a small dressing over the puncture wound, which can be removed after a few hours.

Special Issues
Lactose/dairy intolerance is thought to be over-diagnosed, with many parents thinking that their children are lactose intolerant, when they may well not be. This test provides an opportunity to confirm, or refute, this diagnosis, which is important given the value of dairy in a balanced diet.

Short Description
A lactose tolerance test (LTT) is performed in cases of suspected lactose (the form of sugar found in dairy foods) intolerance.

Keywords
Lactose, lactose intolerance, lactose tolerance test, LTT