Chromogranin A

Chromogranin A (CgA) is a protein released from neuroendocrine cells, i.e. those thatre capable of producing hormonesin response to signals from the nervous system. They are located in organs throughout the body, mainly the adrenal medulla and the sympathetic part of the nervous system, and the substances they produce can participate in the regulation of various processesin the body.

Neuroendocrine cells produce chromogranin A, whichra either itself is directly converted to hormonesor regulates calcium levels in the cells, affecting the secretion of other substances. Somere can affect the constriction or dilation of the diameter of blood vessels or bronchial wall muscles, which regulates the level of blood pressure or lung capacity in the body.

Clusters of neuroendocrine cells are also present in the gastrointestinal tract, intestines or pancreatic islet cells, where the hormones they produce regulate the intensity of intestinal contractions (peristalsis) and the processes of digestion and absorption that occur there.

Sometimes it happens that benign or malignant tumors develop in the endocrine glands in whichr there are neuroendocrine cells, whichre capable of producing chromogranin A. Then, excessive amounts of the hormonesformed from it enter the bloodstream, either continuously or intermittently, causing a characteristic setof symptomsknown as carcinoma syndrome.

Chromogranin A can therefore be regarded as a nonspecific tumor marker, and monitoring its levels helps detect and diagnose such tumors. However, there are a number of non-cancerous conditions or drugs that can cause an increase in chromogranin levels, hence additional diagnostics ordered by a physician are necessary.

Chromogranin A – when to perform the test?

The determination of chromogranin A levels is used mainlyin the diagnosis of carcinomasof the gastrointestinal tract-gastrointestinal-pancreatic neuroendocrine tumors (GISTs) and lung tumors.

In patients with gastrointestinal neuroendocrine tumors, the diagnostic sensitivity of CgA ranges from 10-100%, with a specificity of 68-100%. The concentration of chromogranin A correlates with tumor mass, so it has applications in determining the prognosis of the course of the disease and monitoring the course of its treatment.

CgA concentration correlates with tumor mass, so it has applications in determining the prognosis of the course of the disease and monitoring the course of its treatment.

Sometimes chromogranin determination is used as an adjunct in the detection of other cancersw that secrete hormones affecting the nervous system. These come from: the adrenal medulla (phaeochromocytoma, neuroblastoma), pancreas (insulinoma), lung (smallr cancer), thyroid (medullary carcinoma), prostate. In this case, the test is often accompanied by the determination of other markerse.g.: 5-hydroxyindoleacetic acid in the daily urine collectione.

Chromogranin A – who should do the test?

Persons with symptoms of gastrointestinal or pulmonary carcinomasly:

• accidental redness of the skinry face and neck,
• acceleration of heart rate, spikes in blood pressure,
• dizziness,
• excessive sweating,
• recurrent vomiting and diarrhea, resulting in weight loss,
• symptoms of bronchospasm, such as shortness of breath, coughing, inspiratory wheezing,

These symptoms usually appear episodically, and can sometimes be provoked by the consumption of alcohol or spicy foods.

Also, patients with carcinomas can develop dangerous complications, such as:

• heart disease resulting from the insertion of its valves,
• intestinal obstruction that may be caused by metastasis of the cancer to the lymph nodes of the gastrointestinal tract,
• carcinomatous metastasis causing problems with excessively low blood pressure and difficult breathing,

Przygotowanie do badania chromograniny A

Zgłaszając się na pobranie krwi w celu zbadania poziomu chromograniny A, pacjent powinien być na czczo (nie przyjmować pokarmów przez co najmniej 8 godzin), gdyż stężenie CgA jest wyższe po zjedzeniu posiłku.

Niektóre leki mogą wpływać na zwiększenie stężenia CgA. Należą do nich substancje z grupy inhibitorów pompy protonowej (np. omeprazol), inhibitorów receptora H2 (np. ranitydyna). Wskazane jest więc, by przed badaniem stężenia chromograniny odstawić te leki 7–14 dni, koniecznie po uprzedniej konsultacji z lekarzem.