Lactose Tolerance Blood Test

Lactose Tolerance Blood Test

Quick Overview

Helps diagnose lactose intolerance in individuals who have difficulties digesting dairy products, or sometimes as part of an investigation of malabsorption.

Test #7675


Availability: In stock


Fasting for 8 hours required.

Test Results 4-5 days. May take longer based on weather, holiday or lab delays.

Important note: The test must be scheduled at a PSC capable of administering the dose. Please call 1-866-MyQuest (866-697-8378) to schedule.

Lactose tolerance tests measure hydrogen in the breath or changes in the level of glucose in the blood after a person is given a drink containing a standard amount of lactose, thus determining whether the individual is capable of proper digestion of lactose.

A lactose tolerance test is a test that measures how well your body can process lactose, a type of sugar found in dairy products. Normally the body is able to process milk and other dairy products thanks to an enzyme in the intestines called lactase, which breaks lactose down during digestion.

However, some people have levels of lactase that are lower than normal. For these people, instead of breaking down the milk sugar (lactose), the lactose will persist in the intestines and ferment. This inability to digest lactose is referred to as lactose intolerance.

Testing is ordered when a person has signs and symptoms that suggest lactose intolerance that develops 30 minutes to 2 hours after ingesting milk or other dairy products. Some of these include:

  • Abdominal pain and bloating
  • Diarrhea
  • Nausea
  • Flatulence (passing gas)

According to the National Digestive Diseases Information Clearing House (NDDIC), lactose intolerance occurs more often in older adults and babies who are born prematurely.


Fasting specimen, 1/2-hour, 1-hour, 2-hour, and 3-hour specimens

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