Stomach Acid Tests

There are multiple Stomach or Gastric Acid Tests, five of which are detailed below. Self-care tests also exist. With age, parietal cells tend to make less HCL. (See parietal cells file) It is therefore useful to know one’s stomach acid levels and-or to be aware of the clinical signs that indicate low stomach acid and thereafter, to intervene holistically in order to boost gastric acid, the effects of which break down food, unfold proteins, absorb key nutrients, nutrients and vitamins (B-12, zinc, iron etc) remove microbes, optimize the immune and energy systems and so much more.

The Gastric Acid Secretion Test

The GAST is a highly invasive and expensive test that is typically only used by medical doctors if the individual has a diagnosed stomach ulcer.  It is only covered by insurance in cases of stomach ulcers (1)

Using this test, medical Doctors find it helpful to see if the anti-ulcer medication that was prescribed is working and to see if there is any material coming into the stomach from the intestines.

This test consists of having tube inserted into your stomach through the esophagus in order to suck out any existing stomach fluid.  You will also need an injection of the hormone gastrin into the body in order to stimulate the stomach cells to release acid.

The stomach should normally have 20-100mL of fluid with a pH between 1.5-3.5.  A low level of fluid and/or high pH would be indicative of either achlorhydria or hypochlorhydria, which are stomach acid diseases (See Disease Sectin)

The Heidelberg Stomach Acid Test

For Conventional medicine, this test is the gold standard test for hypochlorhydria as it can give an accurate result regarding the capability of the stomach to produce acid.  It typically costs around $350 and most insurance plans do not pay for it.

This test works by using a small capsule with a specific wireless electronic transmitter that records the pH of the stomach as the patient drinks a solution with small amounts of baking soda (hydroxide (OH-) ions from bicarbonate of sodium).

The baking soda will naturally neutralize the HCL in the stomach.  If the acid does not return to normal after the baking soda is swallowed than that is a positive test for hypochlorhydria (2).The modality thereof is as follows.  Avoid any acid suppressing drugs for at least 4 days before the test. Fast for 8-12 hours Swallow the small electronic capsule Drink a solution of baking soda The test will record the time it takes to reacidify.

This test can determine if the patient has too much acid production (hyperchlorhydria), too little or none at all, called achlorhydria (3). This test will show a graph of your pH levels at regular intervals of time.  The video below shows more detail if you are interested.

The CBC and CMP

 Low stomach acid levels can also be diagnosed via a complete blood counts (CBC) and comprehensive metabolic panels (CMP).  CBC and CMP  are routine tests for medical doctors and are nearly always covered by insurance.  Below, key parameters.

Low Chloride Levels:  One of the main components of hydrochloric acid is chloride.  When we see low chloride levels in the blood under 100 (101-106 is functionally normal) than it is a sign of low HCL.

Abnormal Serum Protein and Serum Globulin Levels:  Since HCL is needed for protein digestion, when these levels are abnormal such as a serum protein under 6.9 or over 7.4 g/dL and globulin level under 2.4 or over 2.8 g/dL than it could be a sign of low HCL.  Especially if liver enzymes are relatively normal.

Low Phosphorus Levels:  If phosphorus levels are low, with a vitamin D deficiency and/or hyperparathyroidism than it may be a sign of low HCL production.

High BUN Levels: A lack of stomach acid may result in a high amount of nitrogenic waste (from poor protein digestion) in the bloodstream.  This can be seen as a BUN (blood urea nitrogen) level of 20 or more.

Abnormal MCV//MCH/MCHC:  This has to do with the size of the red blood cell (RBC). Methylation with B12 is a critical part of the RBC maturation process in the bone marrow.  Inadequate B12 will result in immature RBC’s that will be larger and less effective at carrying oxygen to cells. HCL is also necessary for iron absorption, so if these numbers are below normal along with low Hct, Hbg, etc. it could be an iron deficiency related to low HCL. Normal MCV should be between 85-92 Normal MCH should be between 27.7-32% Normal MCHC should be between 32-36%

Additional Lab Testing

High Homocysteine Levels:  Stomach acid is critical for B12 absorption (4).  B12 is one of the key components of methylation which keeps homocysteine levels between 5-8 umol/L.  If B12 levels are low, than homocysteine will be elevated.

Low B12 Levels:  Intrinsic factor is a glycoprotein in the stomach that is necessary for B12 absorption.  With inadequate HCL production, intrinsic factor will be unable to work effectively and the individual will develop a B12 deficiency (5). When a patient history indicates symptoms of low stomach acid levels and 2 or more of these findings are on lab work than it is a good clinical assumption that the individual needs to focus on strategies to improve HCL production. (Ie, The Complete Thyroid Report looks at all of these metabolites)

The Baking Soda Stomach Acid Test

This very easy, at home test to look at your stomach acid levels that is basically free other than the cost of ¼ tsp of baking soda.  This is a good one to do because it is safe and has no major cost involved.

This test works by creating a unique chemical reaction within your stomach that occurs when you mix the OH- ions of the baking soda with the hydrogen (H+) ions within the bodies stomach acid (HCL).  The natural results should be a carbon dioxide gas production which will cause a burping effect.

This test does have many variables that can cause false positives or negatives.  To minimize these variables and get a greater degree of accuracy, I recommend performing this test on 3 consecutive mornings to find an overall average.

It is also best to do this test first thing in the morning before eating or drinking anything.  You are looking for pattern of results, not a simple one-time “yes” or “no.”

There is no published data on this method and the reliability is up for question.  The results can vary from person to person depending upon how the individual interprets what they are experiencing.  However, I still like it as a baseline measure and it is simple enough that you can retest every month to see if you notice changes.


Mix ¼ tsp of baking soda in 4-6 oz of cold water, first thing in the morning before eating or drinking anything. Drink the baking soda solution Time how long it takes for a burp or belch to come about. Go up to 5 minutes.  If you have not burped or belched within 5 minutes than it would be a sign of insufficient stomach acid production.

If you have early and repeated belching than it may be due to too much stomach acid.  However, it is important not to confuse these with small little burps from swallowing air when drinking the solution.  Any belching after 3 minutes is an indication of low stomach acid levels and overall HCL production.

Betaine HCL Challenge Test

This is another at-home test that is quite reliable in my opinion, although there is no scientific data that I am aware of to prove this.  There are studies that show that supplemental betaine HCL does reacidify the stomach for a period of time (6).

To Perform the Test do the FollowingBuy some Betaine HCL with pepsin (we use Acid Prozyme) Eat a high protein meal of at least 6 ounces of meat (you can have veggies too) In the middle of the meal (never in the beginning) take 1 Betaine HCL pill Finish the meal and observe what you notice.

Outcomes: The patient doesn’t notice any change. He or she has therefore low stomach acid levels. On the other hand, if the patient notices indigestion or heaviness in the chest than these are signs that the patient has adequate stomach acid levels. To avoid false positives, this test should be done two or three times. (7)

Discussion & Disclaimer

The baking soda test is not accurate enough to rule out low stomach acid. To rule out low stomach acid, the Heidelberg test or Betaine HCL challenge test are better. The most reliable test one can perform at home is the Betaine HCL challenge test. On the web, the viewer can  find several health websites who will try to sell a kit to perform the steps mentioned above. This is not necessary. This test can be performed safely for around $20 or less, price of the Betaine HCL supplement.

Also, there is a deleterious interaction between NSAIDs and Corticosteroids and Betaine HCL.  The risk of getting ulcers and gastritis in the stomach is increased wit this combination. Except for the baking soda test, the patient should  consult a health-care practitioner before using any of the other tests. Each case of low stomach acid is unique and will require a custom dosage of HCL.

To learn about the cutting edge holistic techniques to better control and reverse low stomach acid, schedule a consult-coaching.

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1. Stomach Acid Test – MedlinePlus  The test is done after you have not eaten for a while so fluid is all that remains in the stomach. Stomach fluid is removed through a tube that is inserted into the stomach through the esophagus (food pipe). A hormone called gastrin may be injected into your body. This is done to test the ability of the cells in the stomach to release acid. The stomach contents are then removed and analyzed. How to Prepare for the TestYou will be asked not to eat or drink for 4 to 6 hours before the test. How the Test will Feel You may have some discomfort or a gagging feeling as the tube is inserted. Why the Test is Performed Your health care provider may recommend this test for the following reasons: To check if anti-ulcer medicines are workingTo check if material is coming back up from the small intestine To test for the cause of ulcersThe normal volume of the stomach fluid is 20 to 100 mL and the pH is acidic (1.5 to 3.5). These numbers are converted to actual acid production in units of milliequivalents per hour (mEq/hr) in some cases. Normal value ranges may vary slightly depending on the lab doing the test. Abnormal results may indicate: Increased levels of gastrin can cause increased release of acid and may lead to ulcers (Zollinger-Ellison syndrome). The presence of bile in the stomach indicates material is backing up from the small intestine (duodenum). This may be normal. It may also happen after part of the stomach is removed with surgery. Risks There is a slight risk of the tube being placed through the windpipe and into the lungs instead of through the esophagus and into the stomach.
2. DePestel, D. D., Kazanjian, P. H., Cinti, S. K., Kauffman, C. A. and Carver, P. L. (2004), Magnitude and Duration of Elevated Gastric pH in Patients Infected with Human Immunodeficiency Virus After Administration of Chewable, Dispersible, Buffered Didanosine Tablets. Pharmacotherapy, 24: 1539–1545.
3. Stack BH. Use of the Heidelberg pH capsule in the routine assessment of gastric acid secretion. Gut. 1969;10(3):245-246.
4. Rasool S, Abid S, Iqbal MP, Mehboobali N, Haider G, Jafri W. Relationship between vitamin B12, folate and homocysteine levels and H. Pylori infection in patients with functional dyspepsia: A cross-section study. BMC Research Notes. 2012;5:206.
5. King CE, Leibach J, Toskes PP. Clinically significant vitamin B12 deficiency secondary to malabsorption of protein-bound vitamin B12. Dig Dis Sci. 1979 May;24(5):397-402. PMID: 378625
6. Yago MAR, Frymoyer AR, Smelick GS, et al. Gastric Re-acidification with Betaine HCl in Healthy Volunteers with Rabeprazole-Induced Hypochlorhydria. Molecular pharmaceutics. 2013;10(11):4032-4037.
7. There are different reasons to get a false positive Didn’t Consume Enough Protein:  Low protein meals don’t need much HCL and therefore the supplement can cause too much of an increase.  Be sure it is as close to 6oz of meat as possible. Took the Capsule Before the Meal: This will almost always cause indigestion as  body isn’t ready for the supplement. Have Esophageal Sphincter Dysfunction:  For some individuals, they may have a hiatal hernia or poor contractile activity of the esophogeal sphincter that can cause an increase in indigestion like symptoms.  It is always good to get a medical exam to rule these things out before doing the test if possible.

Additional resources

Chernecky CC, Berger BJ. Gastric acid secretion test (gastric acid stimulation test). In: Chernecky, CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:549-602.
Schubert ML, Kaunitz JD. Gastric secretion. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 50.

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