This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Investigation

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Tests

The most common cause of lactose intolerance is secondary lactose intolerance. The use of an Exclusion diet is the simplest diagnostic method:

  • exclusion diet (low lactose) (symptom improvement) and then reintroduction (symptom recurrence). Usually improve within 48 hours of exclusion

More detailed investigation may be undertaken in some cases:

Diagnosis is often strongly suggested by the presence of reducing sugars in the stool.

Breath tests may also be used

  • when colonic bacteria act upon undigested lactose, hydrogen is formed. Breath hydrogen analysis may be useful in the diagnosis of lactose intolerance

Notes:

  • testing for reducing substances in the stools is not always helpful. Infants with positive reducing substances may have sufficient lactase activity
    • because lactase breaks down lactose into glucose and galactose, the presence of 20-25 milligrams per deciliter of glucose above fasting levels indicates sufficient levels of lactase

Related pages

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page

The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.

Connect

Copyright 2024 Oxbridge Solutions Limited, a subsidiary of OmniaMed Communications Limited. All rights reserved. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions receives funding from advertising but maintains editorial independence.