Recently, I have been making the added effort to unravel the twisted knot that seems to be part of having carcinoid cancer and net cancer. Understand all of the tumor markers is a large part of unraveling that knot. If you’re interested in understanding all of the markers that affect us then you can read my post on Understanding 5-HIAA. Today, understanding chromogranin A, or CgA, is my goal. 🙂 Here’s a bit about tumor markers to start our conversation.
Tumor markers are substances, often proteins, that are produced by the cancer tissue itself or sometimes by the body in response to cancer growth. Because some of these substances can be detected in body samples such as blood, urine, and tissue, these markers may be used, along with other tests and procedures, to help detect and diagnose some types of cancer, predict and monitor a person’s response to certain treatments, and detect recurrence. Read More at Lab Tests Online
The Biological Purpose Of Chromogranin A
For our purposes of understanding carcinoid and net cancer, Chromogranin A is a protein that is secreted by our neuroendocrine cells. My understanding is that it is used to signal the cell to perform a certain function. There are 2 types of functions caused by the chromogranisn on cells. The first is Autocrine is when the cell itself is changed by the CgA. The second is paracrine and is the functions that are caused in other cells by the neuroendocrine cell and the Cga. Just in case ya wann a know! 😀
CgA is co-stored with a tissue-specific peptide hormone or neuropeptide and exerts an autocrine and paracrine effect on secretory activity of the neuroendocrine cells. Cumulative evidences suggest that CgA’s derived peptides are involved in a wide range of activities, like regulation of blood pressure (catestatin), glucose metabolism (pancreastatin, catestatin), neuroprotection (serpinin), and tumor angiogenesis (vasostatin I, vasostatin II). Read More at eMedicine
What Is The Clinical Purpose of Chomogranin A
For patients with carcinoid or neuroendocrine cancer (net cancer) the answer is pretty straight forward. 5-HIAA and CgA are typically the two standard tests doctors use to diagnose and track carcinoid and net cancer. These tests are often paired with imaging tests like an MRI, or an X-Ray, depending on where the tumors are located. Of course, there are more tests that can be done but we are focusing on CgA for this post. 🙂
Blood/urine tests. The doctor may need samples of your blood and urine to check for abnormal levels of hormones and other substances. Urine tests check the amount of 5-HIAA (see the Introduction section). Measurements of serotonin levels may also be taken. A doctor may be able to diagnose a carcinoid tumor from a urine test alone. A blood test to measure chromogranin-A may be needed since the serum serotonin level often changes and may not be as useful as a chromogranin-A test. Read More At Carcinoid.Net
We should be aware of our normal ranges and if there are any large changes in our CgA levels after we’ve established a baseline. FYI ~ ng/mL is the abbreviation for nanograms per milliliter and µg/L stands for micrograms per liter.
Although it varies widely with the techniques used, the reference ranges for serum chromogranin A are as follows:
Less than 36.4 ng/mL (conventional unit)
Less than 36.4 µg/L (system international) Read More at eMedicine
Diagnosis – Typically, the level of chromogranin A in our blood stream is low for a healthy person. So, an increased CgA level in a person with symptoms of carcinoid or net cancer may indicate the presence of a tumor. Typical symptoms include flushing of the face and neck (reddening of the skin), diarrhea, nausea, vomiting, rapid heart rate, wheezing, coughing, difficulty breathing. There are other symptoms but these are the most common. I don’t flush so these are not set in stone.
However, the test is not perfect. It is possible to have a carcinoid or net cancer even if the concentration of CgA is normal. So, we need to see a specialist to help us through these test and to read the results. 🙂
False Positives – Unfortunately, CgA can often return false positives because of other pre-existing conditions. For starters, false-positive may because of impaired renal function, parkinson disease, high blood pressure, pregnancy, chronic atrophic gastritis (type A) , treatment with anti-secretory medications, and PPIs Read More
Tracking – If your tumors do produce CgA in excess of normal levels then CgA can be measured before and after treatment. If CgA levels drop after treatment then that treatment may have been effective. If levels never drop or begin to rise after dropping then the treatment might not have been effective. The amount of CgA is often used to keep track of your “tumor burden” or how much cancer you have.
So the long and the short of it seems to be that CgA is a great tool to diagnose and help keep an eye on your carcinoid or net tumor growth as long as you are also using other tools as well. If you’re a person that is wondering about your diagnosis then CgA is only the beginning and you need to see a specialist to conduct additional tests. If you have tumors that already produce CgA then, in conjunction with other tools, CgA seems to be a fairly useful to show the overall direction and effectiveness of your cancer treatments.