It is possible for a person to have elevated levels of chromogranin A, or CgA, without there being anything wrong with him health-wise, according to PubMed. However, elevated levels of chromogranin A is often a sign of neuroendocrine and other carcinoid tumors.
In one study, most patients with elevated CgA levels had neuroendocrine tumors, according to PubMed. Others had tumors called adenocarcinomas, and some simply had gastritis, or inflammation of the stomach. Of 44 patients with elevated serum CqA levels, nine seemed to have nothing wrong with them.
Chromogranin A is a type of protein that is a member of the granin family, explains Mayo Clinic. It's also a type of polypeptide. It can be used to discover carcinoid tumors because granins are abundant in the central and peripheral nervous systems as well as in the endocrine and neuroendocrine systems. Carcinoid tumors almost always secrete chromogranin A as well as certain peptides, amines and even neurotransmitters such as serotonin.
Most carcinoid tumors develop in the digestive tract, with a small percentage found in the respiratory tract. Some are also found in the testicals or ovaries, according to Cancer.net. Some are even found in the appendix. Carcinoid tumors are often slow growing and can be silent for years.