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Breath Hydrogen Partial Pressure (H₂) at 50 mmHg or Glucose in Exhaled Breath

Published: August 9, 2026Updated: August 16, 2026

This test measures small amounts of hydrogen gas and glucose in your breath to help assess certain digestive or metabolic conditions.

Quick summary

["Helps detect issues like bacterial overgrowth or sugar metabolism problems through breath analysis."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
2437-2
Short code
Breath H2 p 50 g Glc PO
Synonyms
Breath H2 p 50 g Glc PO
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
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

Why This Test Is Done

Your doctor may order this test if they suspect conditions like small intestinal bacterial overgrowth (SIBO), diabetes-related issues, or other metabolic disorders. It’s often used as a non-invasive way to monitor gut health or glucose processing without drawing blood.

How the Test Works

You’ll exhale into a special device that measures hydrogen levels (often linked to gut bacteria) and glucose. The machine analyzes these to generate a reading, which may be compared to a baseline or threshold value.

Sample Collection

No blood or urine sample is taken. Instead, you’ll exhale into a breath collector for a few minutes, and the test measures gases or chemicals in your exhaled air.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to avoid certain foods or medications that could interfere with results (e.g., high-fiber foods, probiotics, or antibiotics). Follow your doctor’s instructions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated hydrogen in breath can signal bacterial overgrowth in the small intestine, while glucose levels may reflect how well your body processes sugar. These findings can guide treatment for conditions like SIBO, diabetes, or other metabolic disorders.

Short name

Breath H₂/Glucose Test

Frequently asked questions

What does a positive result mean?
A positive result may indicate abnormal bacterial activity in your gut (e.g., SIBO) or potential issues with glucose metabolism, but results depend on clinical context and may require further testing.
Will I need to fast before this test?
No fasting is typically required, but your doctor may advise avoiding certain foods or supplements that could affect breath chemistry, such as high-fiber foods or probiotics.
Is this test painful or uncomfortable?
No, this test is completely painless. You’ll simply exhale into a device for a few minutes, similar to blowing into a straw.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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