Skip to content

Gastric Acid Concentration (24-Hour Quantitative, Serum/Plasma)

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of acid produced in your stomach over a 24-hour period, often assessed via a special capsule or tube placed in your nose.

Quick summary

["Understanding your stomach acid levels can help diagnose conditions like hyperacidity or Zollinger-Ellison syndrome."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
11891-9
Short code
GA from AC.Hadlock82
Synonyms
GA from AC.Hadlock82
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-ac-hadlock
CPT
82553
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 recommend this test if you have symptoms like persistent heartburn, unexplained stomach pain, or signs of acid-related issues. It helps evaluate conditions like gastroesophageal reflux disease (GERD) or unusual stomach acid overproduction.

How the Test Works

You’ll swallow a small capsule or tube that collects acid samples over 24 hours. The samples are then analyzed to determine total acid output in your stomach.

Sample Collection Process

You’ll need to follow specific instructions, such as fasting before the test or avoiding certain foods/drinks. Your healthcare provider will guide you on how to use the collection device and return it for testing.

What to Expect Before the Test

Avoid smoking, caffeine, or alcohol for a few hours before testing. Follow any dietary restrictions your doctor prescribes to ensure accurate results.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Gastric Acid Level

Frequently asked questions

How long does it take to get results from this test?
Results are typically ready within 1–2 weeks after the lab processes your samples, depending on the lab’s workflow.
What does a high or low gastric acid level mean?
High levels may signal conditions like excessive stomach acid production or rare tumors (e.g., Zollinger-Ellison syndrome). Low levels could indicate long-term stomach inflammation, medications, or other underlying health issues.
Can I eat or drink anything before the test?
No, you’ll need to follow fasting or dietary restrictions provided by your doctor to ensure accurate results. Avoid caffeine, alcohol, or smoking for a few hours before the test.
  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 17, 2026. · Read our editorial policy