Neuroendocrine tumors are abnormal growth and proliferation of specialized cells called the neuroendocrine cells. The gastrointestinal tract is the commonest site for neuroendocrine tumors to occur, followed by the lungs.
Neuroendocrine tumors have gained exceptional attention in the last few years by virtue of a rise in the total number of cases worldwide. The annual prevalence of neuroendocrine tumors worldwide is about 35 per 100000 cases.
Neuroendocrine tumors are often diagnosed incidentally. These tumors are aggressive growths which show rapid metastasis. They are often diagnosed at an advanced stage which reduces the chances of these being cured and are commonly associated with poor prognosis.
This article will let you know the importance of the Chromogranin A test, as a biomarker in the diagnosis and prognosis of neuroendocrine tumors and foods to avoid before a Chromogranin A test.
What Is Chromogranin-A Test?
Chromogranin-A is a valuable marker for neuroendocrine tumors. Yet, it is found to be higher in the disseminated type of tumors rather than restricted neoplastic growths. Chromogranin A is a more frequently used biomarker as compared to chromogranin B and chromogranin C.
A chromogranin a test can indicate the presence of a neuroendocrine tumor but it does not tell anything in regards to disease progression or severity of such tumors. Therefore this test is rarely advised singly and is often done along with other relevant tests to gain an affirmative diagnostic or prognostic value.
Granins are a form of acidic proteins which are a major component of secretory granules of various neuroendocrine and endocrine cells and have the potential to transform into neuroendocrine tumors.
There are several commercially available kits which let you test for Chromogranin-A. These diagnostic kits for chromogranin have no single standardized technique. Some kits work on the principle of ELISA (enzyme-linked immunosorbent assay), while some work on the principles of RIA (radio-immunoassay).
Purpose Of The Test
- High chromogranin in cases of prostate cancer not only suggests a neuroendocrine origin but is also linked to poor prognosis and resistance to hormonal therapy.
- Chromogranin A test is useful in hormonally inactive cases of neuroendocrine tumors.
- The highest values of chromogranin-A are usually found in neuroendocrine tumors of the gastrointestinal tract, particularly the small intestine.
- Chromogranin concentration is a prognostic factor for serotonin secreting neuroendocrine tumors originating from the small intestine.
- Concentration levels of chromogranin often correlate with the size of the tumor and the extent of metastasis.
- Chromogranin A test is also a potential marker to detect relapse or recurrence of neuroendocrine tumors.
- Reduction in levels of chromogranin indicates the effectiveness of the choice of treatment. Therefore, the test can also be used to monitor response to treatment.
Reference range: Below 36.4 ng/mL
False-positive results or abnormally high levels of chromogranin-A can be seen under the following conditions
- Chronic atrophic gastritis
- Inflammatory bowel diseases
- Liver disorders such as chronic hepatitis, liver cirrhosis, and liver failure
- Extreme physical exertion or stress
- Prolonged intake of proton pump inhibitors
- Impaired renal function or renal insufficiency and renal failure
- Hypertension
- Parkinson’s disease
- Rheumatoid arthritis
- Steroid medications
Foods To Avoid Before A Chromogranin-A Test And Other Preparation Needed
Chromogranin A test requires 10 hours of overnight fasting. Also, there are certain foods that should be avoided before a Chromogranin A test as they can interfere with test results and provide inaccurate test results.
- The first and foremost thing is to discuss with your doctor regarding the stoppage of a certain type of medication before the test. Alpha or beta antagonists and aspirin are known to interfere with test results.
- Proton pump inhibitors, a group of medications used for treatment and management of hyperacidity related complaints must be stopped at least two weeks prior to the test.
- Persons who are supposed to undergo a chromogranin A test should avoid taking a heavy meal at least 2 hours prior to the test; reason being, the test results received will be inaccurate due to the simultaneous release of the hormone gastrin immediately after a full meal.
- The patient must preferably report to the laboratory for the test after proper rest and at least 12 hours of fasting. This is because chromogranin levels may be raised 2-3 times the upper limit of the reference range for about 30-90 minutes after a full meal.
- Avoid any kind of over the counter medications at least 12 hours before going to the laboratory for sample collection. Consult your doctor if you need to take any medications before the test.
- Completely avoid or cut off alcoholic beverages and nicotine-containing products.
- Avoid foods that have high sugar content such as pulpy fruits, juices, sweets, or desserts before reporting to the laboratory for sample collection.
- Avoid salty foods before the test. This specifically needs to be followed by patients who are already diagnosed with hypertension because high blood pressure can alter test results.
Apart from maintaining food-related restrictions, it is equally important to report any physical exertion, such as vigorous exercise or injury. This is because stress is one of the potential factors which can cause false-positive results.
Effects of food on Chromogranin A test results have not been explored too well. There are fewer research papers that support the negative impact of certain food substances on Chromogranin A test results.
Also, there are no studies yet to prove the difference in chromogranin levels in fasting and non-fasting states. It is, therefore, wiser to consult your doctor regarding appropriate preparation for a chromogranin A test along with foods and medications that must be avoided to achieve accurate results.
Although chromogranin A test is a valuable tool for diagnosis, prognosis, and monitoring treatment response, it also has its own set of limitations as the test results can be easily altered by certain foods, medications, and also due to conditions other than neuroendocrine tumors.
Dr. Himanshi is a Homoeopathic consultant and currently working as a lecturer in Post-graduate faculty of Homeopathy, Parul University, Vadodara. Completed BHMS and MD in Homeopathy in January 2018 and also has a clinical experience of about 6 years. Personal interests include reading, spending time with family and traveling.
