What are the other Names for this Test? (Equivalent Terms)
- CgA Blood Test
- Parathyroid Secretory Protein 1 Blood Test
What is Chromogranin A Blood Test? (Background Information)
- Chromogranin A (CgA) is a protein secreted by certain hormone-producing cells, called the neuroendocrine cells. It regulates the activity of endocrine, paracrine, and autocrine responses
- Cells that release hormones are called, endocrine cells. If they receive input from neurons, they are called neuroendocrine cells. Hormones are chemical messengers that travel through the blood and can affect cells, far from the original cell
- Paracrine cells release chemical messengers in the surrounding medium. They only affect nearby cells. Autocrine cells release chemical messengers that only affect them
- Neuroendocrine cells are concentrated in organs known for their hormone production. These include the pancreas, adrenal glands, and thyroid gland, as well as other glands
- Neuroendocrine cells release chromogranin A along with their hormones, to help regulate their hormones’ activity. Chromogranin A inhibits the functions of the original endocrine cells, along with the functions of paracrine and autocrine cells
- Blood chromogranin A levels corresponding to normal hormonal processes in a healthy person, are relatively low. However, in the presence of hormone-secreting neuroendocrine tumors, chromogranin A levels can rise significantly
- The Chromogranin A Blood Test is a test to assess the levels of chromogranin A in blood. It is used to diagnose neuroendocrine disorders, including certain types of cancers
What are the Clinical Indications for performing the Chromogranin A Blood Test?
Following are the clinical indications for performing a Chromogranin A Blood Test:
- Monitor treatment of neuroendocrine disorder
- Elevated heart rate
- Excessive sweating
- Weight loss
- Pain in the upper abdomen or back (flank pain)
- Pale appearance
- Persistent headache
How is the Specimen Collected for Chromogranin A Blood Test?
Following is the specimen collection process for Chromogranin A Blood Test:
Sample required: Blood
Process: Insertion of a needle into an arm vein.
Preparation required: No special preparation is needed prior to the test.
What is the Significance of the Chromogranin A Blood Test Result?
High chromogranin A levels may indicate:
- Carcinoid tumor
- Undetermined neuroendocrine disorder or tumor
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
- Chromogranin A levels are directly related to the mass of a tumor, but not to its severity
- The American Cancer Society states that 11,000-12,000 neuroendocrine tumors are diagnosed each year, in the United States
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.
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References and Information Sources used for the Article:
Hendy, G. N. (1995). Chromogranin A. Clinical and Investigative Medicine, 18(1), 47-65.
Lab Tests Online (2012, November 8). Retrieved June 7, 2014 from http://labtestsonline.org/understanding/analytes/chromogranin/
Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.