lactose intolerance, How is lactose intolerance diagnosed?

Lactose intolerance can be hard to diagnose based on symptoms alone. People may think they suffer from lactose intolerance because they have digestive symptoms; however, other conditions such as irritable bowel syndrome can cause similar symptoms.

Two tests are commonly used to measure the digestion of lactose.

Hydrogen Breath Test. The person drinks a lactose-loaded beverage and then the breath is analyzed at regular intervals to measure the amount of hydrogen. Normally, very little hydrogen is detectable in the breath, but undigested lactose produces high levels of hydrogen. Smoking and some foods and medications may affect the accuracy of the results. People should check with their doctor about foods and medications that may interfere with test results.

Stool Acidity Test. The stool acidity test is used for infants and young children to measure the amount of acid in the stool. Undigested lactose creates lactic acid and other fatty acids that can be detected in a stool sample. Glucose may also be present in the stool as a result of undigested lactose.

Because lactose intolerance is uncommon in infants and children younger than 2, a health professional should take special care in determining the cause of a child’s digestive symptoms.