Contents
Chromogranin (CgA) is a protein – glycoprotein, produced in neuroendocrine tumor cells of the gastrointestinal tract (e.g. carcinoid syndrome, pheochromocytoma). It is one of the tumor markers used in laboratory diagnostics. One of the indications for CgA testing is the suspicion of a phaeochromocytoma.
What exactly is CgA chromogranin?
Chromogranin CgA is actually one of the tumor markers. It is a protein (glycoprotein) produced in the cells of gastrointestinal neuroendocrine tumors. These are tissues with cells that secrete hormones under the influence of nerve stimulation. Its examples in the body are: adrenal medulla, which under the influence of nerve stimulation, produces adrenaline and noradrenaline, pancreatic islets that secrete, inter alia, insulin, and clusters of neuroendocrine cells in the digestive system, which produce the so-called gut hormones that regulate digestion and absorption) and in many other parts of the body. A rise in the level of chromogranin A in the blood may suggest a cancer or another condition that needs to be monitored. In a healthy person, under normal conditions, the concentration of CgA chromogranin is low. The function of this protein is not fully understood, but its role in the nervous, cardiovascular and endocrine systems is known. In addition, CgA (as mentioned at the beginning) serves as a tumor marker in laboratory tests.
A neuroendocrine tumor is formed when cells divide uncontrollably, and each cell carries a load of CgA chromogranin. As a consequence, the level of this protein in the blood and tumor tissue increases. Detecting this may mean that we are dealing with a neoplastic process.
When do we do the chromogranin test?
The main purpose of this study is the diagnosis and treatment monitoring and prognosis of neuroendocrine neoplasms. In addition, we test chromogranin in the body in the following cases:
- Suspicion of phaeochromocytoma (as a cause of secondary hypertension); it is a benign tumor, usually found in the medulla of the adrenal gland, that produces adrenaline and neoadrenaline, often in large amounts. This is evidenced by sudden, large increases in blood pressure, combined with pale skin and increased heart rate.
- Suspicion of a gastrointestinal neuroendocrine tumor (carcinoid tumor) is indicated by abdominal pain, constipation, diarrhea, as well as paroxysmal redness of the facial skin. A carcinoid tumor is a benign tumor usually found in the small intestine that produces serotonin. It can also develop in the lungs.
The hormones produced by the above-mentioned neuroendocrine neoplasms carry the following symptoms:
- acceleration of the heart rate,
- high blood pressure
- flushing redness of the face and neck,
- nausea,
- vomiting and diarrhea
- coughing and wheezing.
Testing the level of CgA (chromogranin) in combination with other tests helps to make an appropriate diagnosis.
Chromogranins – a study
- Material for chromogranin testing: serum.
- Preparation for the test: on an empty stomach (at least 8 hours). Before performing the test, inform your doctor about current diseases and medications you are taking, including those taken without a prescription (e.g. herbal preparations, dietary supplements). The use of drugs from the group of proton pump inhibitors or H2 receptor inhibitors also affects the test result.
- The course of chromogranin testing: one-time blood sampling from a vein in the arm (usually around the elbow bend). The material is placed in a test tube and subjected to further laboratory analysis.
- Waiting time for the chromogranin result: 1 day.
- Normal: below 36.4 ng / ml. It is worth remembering that the reference values may differ from one laboratory to another.
- Notes: CgA is present in the adrenal medulla, in endocrine cells of the gastrointestinal tract, in the sympathetic nervous system, in pancreatic islet cells. The determination of the concentration of chromogranin is used to determine the endocrine nature of the tumor located in the stomach, intestines and pancreas. Under normal conditions, low levels of chromogranin are found in the serum. Therefore, it is a non-specific granular marker of neuroendocrine tumors – carcinoid, pheochromocytoma, insulinoma, gastrinoma.The presence of CgA in the cells can also be detected by histopathological examination of a sample taken during a tumor biopsy.
The presence of CgA chromogranin in cells can also be detected by histopathological examination of a sample taken during tumor biopsy.
There are no contraindications for CgA testing as it is enough to collect only a small amount of venous blood.
Analysis of CgA chromogranin test results
In order for the doctor to make a reliable diagnosis, it is necessary to inform him:
- about current diseases,
- about taking all medications (even those over the counter),
- about the use of dietary supplements and herbal medicines,
- on the possible carrier of blood-borne pathogens such as HIV or hepatitis viruses.
CgA and standards
Normal blood chromogranin A values are below 36.4 ng / ml. However, it should be remembered that the test result may vary depending on the particular laboratory, equipment, or test labeling techniques. Therefore, to eliminate the risk of false results, subsequent CgA tests should be performed in the same laboratory.
Interpretation of CgA chromogranin results
Typically, in healthy people, CgA chromogranin is low in the blood. The recognition of its high concentration raises the suspicion of a developing neoplastic process in the cells that produce it. Benign and malignant neoplasms:
- carcinoid,
- prostate cancer,
- pancreatic cancer,
- pheochromocytoma,
- small cell lung cancer,
- neuroblastoma.
Simultaneously with the chromogranin test, it is recommended to test other tumor markers and other tests – e.g. biopsy of suspicious tissue. They help to confirm the suspicion. A decrease in CgA levels may indicate the effectiveness of treatment, while an increase thereof may indicate a relapse or illness. Therefore, when analyzing the test results, the general condition of the patient and the results of previous tests should be taken into account.
High levels of chromogranin can also be caused by:
- inflammation of the kidneys,
- chronic stress,
- RA(rheumatoid arthritis),
- inflammatory bowel disease,
- taking proton pump inhibitors (these agents are used to treat peptic ulcer disease),
- taking (chronic) preparations that are effective in peptic ulcer disease,
- disorders of the kidneys, heart and liver,
- high blood pressure,
- liver failure
- heart failure.
It should be remembered that CgA chromogranin is not a completely specific marker of a neuroendocrine tumor. For this reason, there are many diagnostic difficulties, so the CgA test is often not sufficient. The analysis of the results should be made in consultation with a specialist.
Note:
The reduction of the CgA chromogranin in the blood is not diagnostic.