GastroPanel
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Frequently asked questions and answers on GastroPanel and related issues.
| Is 80 % accuracy enough? |
The 80% accuracy of this type of test is high. This figure reflects the followig:
1. All cases were classified into exactly the same categories in these cases (normal, non-atrophic gastritis, advanced atrophic gastritis in the antrum, the corpus or in both). No other test can do this. For example, testing H.pylori alone, there only are two categories - present or absent H.pylori infection. In the diagnosis of atrophic gastritis, the sensitivity and specificity of the GastroPanel is around 90%, which is high. The predictive value of the positive test result (PPV) is around 70% and the negative predictive value (NPV) is virtually 100%. The result is better than or at least as good as what can be achieved in current clinical practice.
2. Comparison was achieved with histology alone. This is not without problem, however. There are many inaccuracies due to sampling errors, the small number biopsies or incorrect microscopy. In fact, the problem can be stated in reverse: endoscopy and biopsy histology alone give the correct diagnosis in only 80% of cases when compared to GastroPanel interpretation.
3. Biopsy histology reflects only a very small part of the mucosa whereas GastroPanel is based upon the function of the whole mucosa. Therefore, GastroPanel gives, at least in theory, the most reliable overall estimate of the status of the antral and corpus mucosa. GastroPanel does not detect local and focal lesions - that is the role of subsequent endoscopy.
4. In endoscopy, the endoscopists can reliably see only macroscopic lesions (ulcers, tumors) - GastroPanel gives estimates of the risks for these specific lesions and diseases.
5. Even though Japanese gastroenterologists commonly claim that they can see gastritis and even H.pylori with endoscopy or magnifying endoscopy, they can I fact offer a good opinion only. Prof Ken Kimura would not agree with this but this is, in my opinion, the case among endoscopists in general (Ken Kimura and some other highly experienced gastroenterologist may be the exception). It has been said, that in the diagnosis of gastritis and atrophic gastritis, endoscopists are assistants to the pathologists - the gastroenterologist take the biopsies and the pathologists make the diagnosis. GastroPanel changes this situation.
| What benefit is GastroPanel to GPs? |
Indeed, GPs benefit from GastroPanel the most. The benefit for gastroenterologists is that GastroPanel prior to gastroscopy may help them to know what to expect in the stomach. If the GastroPanel indicates that the stomach is highly atrophic, they have to be very catious of the cancer risks and take biopsies from every small focal lesion. However, when the Gastropanel shows that the stomach is normal and healthy, all these risk are low and the endoscopist does not need to focus so much on the stomach.
| A patient has atrophic gastritis (AG) without HP-infection and low acid output, what is the recommendation in treating the low acid output? |
1. It is corpus atrophic gastritis (low acidic output) caused by autoimmune disease. Treatment: B12 substitution.
2. Corpus atrophy caused by H.pylori, which is eradicated (breath, stool antigen and biopsy test did not find H. pylori-infection - eradicated H. pylori could be found with quantitative H. pylori Ab-test). Treatment: vitamin B12 substitution if S- B12 low and S-Hcy high.
1. careful diagnostic gastroscopy is necessary - 4-6% of patients with advanced (moderate or severe corpus atrophy) have focal precancerous or even cancerous lesions;
2. the serum levels of vitamin B12 and homocysteine should be tested. Also one should verify that the patient does not have pernicious anemia.
3. if there is low vitamin B12 in serum, vitamin substitution is necessary;
4. there is no specific treatment except vitamin B12 substitution. Because there are no H.pylori antibodies, there is no need for the eradication of H.pylori;
5. if the stomach is severely atrophic, follow-up endoscopies every 5 years may be helpful for excluding the possibility of the development of neoplastic lesions.
| What are the GastroPanel results like in reality? |
Results from "real life" measured in the Service Laboratory of Biohit during its first year of operation in 2002:
| SAMPLES (total) | 144 |
| GASTRIC MUCOSA NORMAL AND HEALTHY | 95 |
| NON-ATROPHIC GASTRITIS | 30 |
| ATROPHIC GASTRITIS IN CORPUS, H.pylori infection | 4 |
| ATROPHIC GASTRITIS IN CORPUS, No H.pylori infectio | 8 |
| ATROPHIC GASTRITIS IN ANTRUM | 5 |
| ATROPHIC GASTRITIS IN ANTRUM AND CORPUS | 2 |
| What is the difference between atrophic gastritis caused by autoimmune disease and H.pylori ? |
Autoimmune atrophic gastritis is one form of atrophic gastritis in the corpus and that induced by H.pylori is another. In Finland, at least 80% of cases of atrophic gastritis in the corpus are caused by H.pylori (they show antibodies in the circulation). It may be that the autoimmune type is slightly more severe than atrophic gastritis caused by H.pylori. However, where the PGI level in both diseases is below 30 ug/l in blood sample both can cause deficiency of vitamin B12 and a high serum homocysteine. In Finland, 5-10% of elderly people have advanced atrophic corpus gastritis (PGI below 30 ug/l) and, as previously stated , 80% of these are caused by H.pylori. In these cases, only H.pylori serology is positive but the breath test and stool antigen test are negative because the bacterial load in the stomach is low (but they have an ongoing infection).
| Do the results of PGI, PGII and G-17 differ between women and men ? |
Prof. Pelao Correa et al evaluated Biohit G-17, PGI and PGII kits in 2002: Serum from 69 male patients (44%) and 88 female patients (56%) was tested. The research group found statistically no significant differences in serum PGI, PGII and G-17 levels between men and women.
| How long does a patient on PPI medication have to wait, for the stomach to return to normal ? |
There has been discussion on whether treatment with PPI causes tachyphylaxis and rebound acid secretion after discontinuation. Both of these phenomena might influence gastrin values after treatment with PPI. Summarizing these studies: abbreviated views:
1. With low doses of PPI given for short periods i.e. 4-6 weeks acid secretion and gastrin values will be back to normal within two weeks - most often already within 7 or 8 days.The duration of the influence is partly dependent on the distribution and degree of gastritis. - In patients with dominantly antral gastritis given low doses for short periods there will be no long lasting effect.
2. With higher doses of PPI and given for longer periods, i.e. 12 weeks or more it takes somewhat longer - 2 weeks or even longer - before acid secretory capacity returns. However gastrin levels are usually a little lower two weeks after discontinuation of PPI. Patients with corpus dominant gastritis given high doses for a longer period will have a more sustained decrease in acidity and therefore higher gastrin levels for a longer period. The change in gastrin is probably not so pronounced.
5. If it is not possible for the patients to discontinue the PPI or other medication, it does not prevent studying them, but it is wise to make a note of the situation. Also the date of previous H.pylori eradication has to be included.
| Why does the ratio of pepsinogen I/pepsinogen II differ from the ratio measured by e.g the EIKEN ELISA kits ? |
Eiken considers that the patient has atrophic corpus gastritis when the ratio of PG I/PGII is below 3.0? Biohit's cut-off is also <3.0.
One overgrowing problem is that there is no international standard for Pepsinogens at the present time
- Biohit has calibrated their PGI ELISA test according to Samloff.
- Eiken: The standard material used in this kit was calibrated with purified pepsinogen I, where the concentration was calculated by the Lowry Method.
Each kit producer needs to estimate the reference ranges. Biohit advises: It is recommended that the given limits are considered as guidelines. Also the PGI results determined for given specimen with assays from different manufacturers can vary due to differences in standardization, assay methods and reagent specificity. Results obtained from other manufacturers' assay methods should not be used interchangeably.
| How are the cut-off values determined ? |
See the the literature references of kit package inserts.
| Is there any consensus for treating patients with functional dyspepsia ? |
Contact a physician for the proper treatment of functional dyspepsia.
| Is there any follow up study concerning whether the performance of gastroscopy has increased or decreased after introducing GastroPanel to the market ? |
Not yet.
| Are MSDS (material safety data sheets) on GastroPanel kits available ? |
Available at request and also on Biohit Extranet pages or from the distributors.
| Are eLisa XL templates to be available for samples run as single samples ? |
The dedicated templates for single samples are available at request and also on Biohit Extranet pages or from the distributors. However, please note that on the Results sheet the matrix presentation of data can be considered as singles, as the results are calculated per well.
| There are too few incubation cover sheets for the microplates in the kit ? |
The cover sheet can be used repeatedly during the same assay. Avoid splashing the contents of the well.
| Is it necessary to keep the diluted wash solution in the refrigerator, when not in use ? |
The concentration of the preservative is calculated for concentrated wash solution. Biohit cannot guarantee that the diluted wash solution would stay uncontaminated over longer periods. If in frequent use, the wash solution can be kept at room temperature in a bottle connected to the washer.
| The IFU does not mention whether one should keep the plate in the dark during the substrate incubation ? |
The kit package insert recommends avoid of direct exposure to light during substrate incubation. The microplate can be covered by aluminium foil or placed in a dark place.
| Can the substrate, stop solution, and wash solution be used interchangeably between PG-1 and G17 assays ? |
Use the substrates as provided in the kit. Stop and wash solutions can be used interchangeably within the GastroPanel kits.
| How fast must the microplate be read after addition of the stop solution? |
Please, read the plate within 30 minutes.
| To whom is GastroPanel targeted? |
GP, laboratories, dyspeptic as well as other patients, who want to know about the organic function of the stomach!
| Why GastroPanel? Why is the Gastrin-17 test included in GastroPanel. Isn't the investigation of Helicobacter pylori infection is enough! |
H. pylori measurements indicate only the possible H. pylori infection. Biohit has developed the unique test panel, the GastroPanel, which enables the diagnosis of Helicobacter pylori infection and atrophic gastritis from a blood sample. GastroPanel is a non-invasive alternative for gastroscopy and can be used as an initial method for examining patients suffering from dyspepsia, H. pylori infection and atrophic gastritis. Moreover, the GastroPanel screens the risks of gastric cancer, peptic ulcer, gastroesophageal reflux disease and Barrett's esophagus.
For the interpretation of the results of the GastroPanel Biohit has developed the easy-to-use GastroSoft computer program, which suggest diagnoses of H. pylori infection and atrophic gastritis. The GastroSoft program also reports the severity, likelihood and location (corpus, antrum or both) of atrophic gastritis. It notifies the user whether further examination with gastroscopy, or vitamin B12 or homocysteine tests, are recommended.
| What articles are published about GastroPanel? |
See www.biohit.com/ diagnostics/literature.
| What is the sensitivity and specificity of GastroPanel in atrophic gastritis compared to histological results! |
They vary in different studies according to the experience of the laboratory, the gastroenterologist and the interpreting pathologist: sensitivity is around 80 % and specificity over 90 %. See www-biohit.com /diagnostics/publications.
| What is the sensitivity and specificity of individual tests? |
This information can be found in the individual instruction manuals.
| Are ELISA tests applicable to automatic ELISA analysers? |
Yes, to the automatic ELISA analysers e.g. Adaltis (PersonaLab and Nexgen Four), Radim, MaxMat, Diasorin, Dade Behring (BEP III), DAS, Dynex DSX, Grifols Tritaurus and others.
| Who is using GastroPanel? |
Service laboratories. General practitioners are using GastroPanel to rank patients with dyspepsia to endoscopy. Population studies: E.g the studies of populations of first degree relatives of gastric cancer patients or the vitamin B12 defiency involved in population studies.
| What are the target groups for GastroPanel? |
Dyspeptic patients, first degree relatives of gastric cancer patients.
| Are GastroPanel tests reimbursed? |
Finland has had from 1.4.2003 reimbursement for Gastrin-17. The other individual GastroPanel tests of Pepsinogen I, Pepsinogen II, H.pylori IgG antibodies have been subject to reimbursement for some time ahead.
| How long can the biopsy specimen stand before the Lactose Intolerance Quick Test is done? |
