It's important to visit your GP if you think you or your child may have lactose intolerance, as the symptoms canbe similar to other conditions.
Before seeing your GP, keep a diary of what you eat and drink, and what symptoms you experience. Tell your GP if you notice any patterns, or if there are any foods you seem particularly sensitive to.
Your GP may suggest trying toremove lactose from your diet for two weeks to see if it helps to relieve your symptoms. This will provide further evidenceof whetheryou're lactose intolerant.
Other tests aren't usually needed, but your GP may sometimes suggest further tests to:
Some of the main tests that may beusedare described below.
A hydrogen breath test is a simple way of determining if you may be lactose intolerant.
You'll be asked to avoid eating or drinking during the night before the test. When you arrive for the test, you'll be asked to blow up a balloon-like bag.This sample of your breath will be tested to find out how much hydrogen is present, measured in parts per million (ppm).
You'll then be given a drink of lactose solutionand your breath will be tested every 15 minutes over the next few hours to see if the level of hydrogen changes.
If your breath contains a large amount of hydrogen (more than 20ppm above your baseline) after consuming the lactose solution, it's likely that you're lactose intolerant. This isbecauselactose intolerance can cause the bacteria in the colon (large intestine) to produce more hydrogen than normal.
In a lactose tolerance test, you'll be given a drink of lactose solution and a blood sample will be taken from your arm using a needle. The blood will be tested to see how much glucose (blood sugar) it contains.
If you're lactose intolerant, your blood sugar levels will either rise slowly, or not at all. This is because your body is unable to break down the lactose into glucose.
In a milk tolerance test, you'll be given a glass of milk (about 500ml) and your blood sugar levels will be tested. If your blood sugar levels don't rise after drinking the milk, you may be lactose intolerant.
Asmall bowel biopsy is rarely used to diagnose lactose intolerance. However, it may be carried out to see if your symptoms are being caused by another condition, such as Gluten intolerance .
In a small bowel biopsy, a sample of your small intestinal lining is taken using an endoscope (a thin, flexible tube with a light and a tiny cutting tool at the end) that's passed down your throat. This will be carried out under local anaesthetic , so it won't hurt.
The sample of intestinal lining will be tested to see how much lactase it contains. If it only contains a small amount of lactase,it's likely you're lactose intolerant. The sample can also be examined to look for signs of possible underlying conditions such as coeliac disease.
Lactose intolerance is a common digestive problem where the body is unable to digest lactose, a type of sugar mainly found in milk and dairy products.
Lactose intolerance is usually caused by your body not producing enough lactase - an enzyme (protein that causes a chemical reaction to occur) that digests lactose.
It's important to visit your GP if you think you or your child may have lactose intolerance, as the symptoms can be similar to other conditions.
There's no cure for lactose intolerance, but most people are able to control their symptoms by making changes to their diet.
Zoe Bastion is an assistant content producer at the BBC. She has had primary lactose intolerance for most of her life.
Gary Alexander is a writer and author who lives in London. He suffered from secondary lactose intolerance for several months after a severe bout of gastroenteritis.