Lactose Intolerance Screening (Gas and Breath Hydrogen)
This test measures gas and hydrogen levels in your breath after drinking a lactose-containing solution. It helps determine if your body struggles to digest lactose, a sugar found in milk and dairy products.
["A positive result suggests possible lactose intolerance, which may cause digestive symptoms after consuming dairy."]
Key facts at a glance
- LOINC
- 82920-0
- Short code
- L pneumo IgA Ser IA-aCnc
- Synonyms
- L pneumo IgA Ser IA-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- CPT
- 82784
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
How the Test Works
You’ll drink a solution containing lactose. Your breath is collected before and after drinking it. Special sensors detect hydrogen gas, which builds up in your system if you can’t digest lactose properly. This gas passes out of your body through your breath.
What to Expect Before the Test
No special preparation is needed, but avoid eating or drinking dairy products for at least 3 days before the test. Stop taking any medications that affect digestion (like probiotics or antacids) unless your doctor approves otherwise.
Possible Symptoms of Lactose Intolerance
If you have lactose intolerance, you might experience bloating, gas, diarrhea, stomach cramps, or nausea shortly after eating dairy products. This test helps identify if these symptoms are linked to lactose digestion issues.
What the Results Mean
Higher than expected hydrogen levels in your breath after drinking lactose suggest lactose intolerance. Your doctor will discuss the results with you and may recommend dietary changes or further testing if needed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Lactose intolerance is common and usually harmless. It can cause discomfort but doesn’t usually lead to serious health problems. If symptoms are severe or persistent, your doctor may recommend a lactose-free diet or other tests to confirm the diagnosis.
Short name
Lactose Breath Test (Screening)
Frequently asked questions
Why did my doctor order this test?
What does a positive result mean?
Can I eat or drink dairy before the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy