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Can PPI consumption cause false-positives for the 13C-urea breath test?

Breath tests are the most accurate way of detecting H.pylori without actually having an endoscopy (stomach examination). Breath tests are especially useful after treatment to make sure H.pylori is cured. Urea breath tests are known to be completely harmless. Either C14-urea or C13-urea tests are used. Read about them at the diagnosis section at http://www.helico.com/diag_breath.html where a diagram can be found. C14-urea breath tests use a radioactive tracer but such a tiny amount that it can be used safely at any age. It is a 15 minute test, convenient and inexpensive. The C13-urea test uses a stable isotope of carbon which is also harmless but requires two breath samples and takes about 30 minutes. Both tests have accuracy greater than 90%.

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Wonderboy123
Posts: 7
Joined: Thu Dec 22, 2022 11:32 pm

Can PPI consumption cause false-positives for the 13C-urea breath test?

Post by Wonderboy123 »

I previously posted about my first-line treatment failing, and I went to see a gastro specialist today.

The specialist wanted to send me off to do a breath test before giving me my second-line treatment, as apparently the rapid antigen stool tests I used to test myself are not accurate (tested positive twice this weekend). The problem is, my previous GP put me on Omeprazole for nearly a month when I saw him for stomach discomfort, and I only stopped taking them last Thursday. Because of the above, the specialist wanted to schedule the breath test in 2-4 weeks, which feels like an eternity away as my swollen and bloated stomach feels almost unbearable (already tried various medicines like Cimetidine, Propranolol, Simethicone, they don't help).

To speed up the process, I am thinking of paying out of pocket for an earlier breath test sometime this week, just so that if it comes back positive I can go to the specialist ASAP and get my second line treatment prescribed, as opposed to waiting until nearly the end of February. If it comes back negative, I will wait until 2 weeks later and do the scheduled test as well.

I've read a lot about PPIs causing false negatives for breath tests because it lowers stomach acid, which in turn means that the H.pylori bacteria will stop producing urease. So what about false positives, is this likely as well? And also, will repeating the breath test so soon again have any affect on the results? Thanks in advance!

Wonderboy123
Posts: 7
Joined: Thu Dec 22, 2022 11:32 pm

Re: Can PPI consumption cause false-positives for the 13C-urea breath test?

Post by Wonderboy123 »

Update: I went ahead and booked one for this Monday, the results just came back negative.

The base reading was -24.9 and the "post" reading was -22.7. Cut off point for a positive diagnosis was DOB <4.0.

Will be taking another test later to see if there's an increase in the figure, as Monday was just a few days after I stopped PPIs.

Helico_expert
Site Admin
Posts: 4600
Joined: Wed Mar 02, 2011 7:20 am

Re: Can PPI consumption cause false-positives for the 13C-urea breath test?

Post by Helico_expert »

delta 2.2% is negative.
However, because you only stopped PPI for a few days, the risk of false negative is high.
perhaps you can get a blood test. if it's negative, then I think you are truly negative.
if your blood test is positive, that just mean you had been expose before, you dont need to pay too much attention to positive blood test result.

alternatively, have you considered an endoscopy examination? even if you dont have H. pylori, it's probably a good idea to see if there is any abnormality in your stomach that causes you all the symptoms.

Wonderboy123
Posts: 7
Joined: Thu Dec 22, 2022 11:32 pm

Re: Can PPI consumption cause false-positives for the 13C-urea breath test?

Post by Wonderboy123 »

Helico_expert wrote:
Wed Feb 22, 2023 11:41 am
delta 2.2% is negative.
However, because you only stopped PPI for a few days, the risk of false negative is high.
perhaps you can get a blood test. if it's negative, then I think you are truly negative.
if your blood test is positive, that just mean you had been expose before, you dont need to pay too much attention to positive blood test result.

alternatively, have you considered an endoscopy examination? even if you dont have H. pylori, it's probably a good idea to see if there is any abnormality in your stomach that causes you all the symptoms.
I have an endoscopy scheduled for tomorrow. Will give an update on the results!

Are you familiar with the OTC rapid stool antigen test kits by any chance? I was wondering how accurate they are as I've been getting positive results from them despite the negative breath tests.

I've used over ten of those and they have been able to track my symptoms (e.g. negative at first during the acid reflux stage, and then started testing positive once my stomach became very swollen, and after antibiotics, it was negative again. Around 6 weeks after treatment my symptoms fully returned, and I consistently tested positive again over the next few weeks). Then out of nowhere, I started testing negative again last week despite my stomach still being swollen (though less swollen compared to the week before). I did not use any PPIs or antibiotics.

This is the kit I used, according to instructions it tests for monoclonal antibodies: https://www.hktvmall.com/hktv/en/main/J ... FHZINI0029

Helico_expert
Site Admin
Posts: 4600
Joined: Wed Mar 02, 2011 7:20 am

Re: Can PPI consumption cause false-positives for the 13C-urea breath test?

Post by Helico_expert »

stool test is generally very accurate.
however, I am not too sure about home test kits.
The accuracy is highly depending on the person processing the specimen.

I still think you should get a blood test done. It would be even better if you can get an endoscopy done.
find out why your breath test is not consistent with your stool test.
I am interested to find out how good is the home test kit.

Wonderboy123
Posts: 7
Joined: Thu Dec 22, 2022 11:32 pm

Re: Can PPI consumption cause false-positives for the 13C-urea breath test?

Post by Wonderboy123 »

Helico_expert wrote:
Thu Feb 23, 2023 10:05 am
stool test is generally very accurate.
however, I am not too sure about home test kits.
The accuracy is highly depending on the person processing the specimen.

I still think you should get a blood test done. It would be even better if you can get an endoscopy done.
find out why your breath test is not consistent with your stool test.
I am interested to find out how good is the home test kit.
Hey Helico_expert, I just got my results from the endoscopy.

Mild antral gastritis was found, CLO test was negative. Samples were taken from the antrum, incisura, and body. Histology found mild inactive chronic gastritis, negative H pylori, mild intestinal metaplasia (complete) in the antral region, mild foveolar hyperplasia, and slight dilatation on some of the body-type glands. Should the metaplasia, hyperplasia and dilatation be of concern? My GI specialist recommended an endoscopy every 3 years because of the metaplasia.

As for the home stool test kit, it is very strange that it came out positive after my symptoms returned. Assuming it is accurate, then it might've been more accurate than the breath test, but it doesn't explain how the Hpylori just went away without any antibiotics. If it is inaccurate, then what would've caused it to give a false positive result, considering that it started testing positive at the peak of my symptoms (entire belly feeling swollen)? The only thing I remembered doing the weekend my home test kits started going negative, was that I had a couple drinks over the weekend (I very rarely drink). Surely a couple glasses of champagne wouldn't have killed the bacteria right? :lol:

To give a bit more information, here's a rough timeline of my symptoms. I took multiple breath tests out of pocket hoping to get a positive result ASAP so I could get treated faster. Also went through about 5 boxes of the home test kits (2 tests each).

Late-Oct to Mid-Nov 2022: Began having acid reflux, which turned into my entire stomach feeling swollen. Prescribed omeprazole, cimetidine, and simethicone for a week which didn't help with the symptoms.
Nov 14, 2022: First time tested positive with the Hpylori home stool kit, very faint line. Tested again in the afternoon, also faint positive line.
Mid Nov - Mid Dec 2022: GP prescribed omeprazole, cimetidine, amoxicillin and erythromycin for 14 days. Symptoms went away immediately over night, and all was fine 2 weeks after treatment.
Mid-December 2022 to Mid-Jan 2023: Acid reflux returned, took multiple home stool tests (should be around 4-5 times) at home which returned negative. Prescribed omeprazole, cimetidine, and simethicone, which helped with the acid reflux.
Mid-Jan - Early-Feb 2023: My entire stomach began to feel swollen, and worsening to the point where if I leaned slightly forward or backward it'd feel very uncomfortable.
Feb 2, 2023: Stopped taking Omeprazole
Feb 4 and 5, 2023: Tested with home stool kit twice, both times positive with a faint line. Symptoms persist, swollen belly at its peak.
Feb 7, 2023: Urea 13 Breath test, Delta Over Baseline 2.20 (Negative). Symptoms persist, swollen belly at its peak.
Feb 9, 2023: Urea 13 Breath test, Delta Over Baseline 2.40 (Negative). Symptoms persist, swollen belly at its peak.
Feb 10, 2023: Tested positive with home stool kit, solid colored line. Symptoms persist, swollen belly at its peak.
Feb 13, 2023 Home stool test kit negative. Urea 13 Breath test, Delta Over Baseline 0.3 (Negative). Symptoms subsided over the weekend, stomach feels like it's getting less swollen.
Feb 15, 2023 Home stool test kit negative. Urea 13 Breath test, Delta Over Baseline 1.4 (Negative). Stomach continuing to feel better.
Feb 23, 2023 Endoscopy, results as above. No significant symptoms aside from two areas feeling swollen when pressed down on (left side of the upper abs, 1 inch to the left of the belly button)

Helico_expert
Site Admin
Posts: 4600
Joined: Wed Mar 02, 2011 7:20 am

Re: Can PPI consumption cause false-positives for the 13C-urea breath test?

Post by Helico_expert »

hmm.. perhaps your home test kit is cross reacting with other gastric bacteria.
I would trust the histology report. the inactive gastritis is the keyword showing that it is now H. pylori free and the immune cells are gradually retreating.

your doctor is right about the metaplasia. depending on the severity, you should monitor every few years. If you are young and healthy, there is a small chance of returning to normal.

your symptoms could be due to certain food. so you might want to have a good diary of what you eat every day and see if you can identify the food that trigger your symptoms.

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