Chromogranin A, despite a number of limitations, is still the most valuable marker of
neuroendocrine tumors (NETs).
Granins belong to the family of acidic
proteins that constitute a major component of secretory granules of various endocrine and neuroendocrine cells, which are components of both the classical endocrine glands and the diffuse neuroendocrine system. These cells are a potential source of transformation into
neuroendocrine tumors. The awareness of potential causes influencing the false results of its concentrations simplifies diagnosis and treatment. One of the disadvantages of this marker is its non-specificity and the existence of a number of
pathological processes leading to an increase in its concentration, which often results in
confusion and diagnostic difficulties. The molecular structure is characterized by a number of sites susceptible to the proteolytic activity of
enzymes, resulting in the formation of a number of biologically active
peptides. Presumably they act as precursors of active
proteins.
Chromogranin expression correlates with the amount of secretory vesicles in neuroendocrine cells. The
peptide chain during biochemical changes becomes a precursor of biologically active
proteins with a wide range of activities. There are a number of commercially available kits for the determination of
chromogranin A, which differ in methodology. We present the evaluation of
chromogranin A as a marker of
neuroendocrine tumors in clinical practice and the possible factors that may affect the outcome of its concentration.