Chromogranin A (CgA)--the influence of various factors in vivo and in vitro, and existing disorders on it's concentration in blood.

Chromogranin A (CgA) is regarded as a major, nonspecific neuroendocrine tumour (NET) marker. The results of CgA blood concentration, however, may actually be influenced by various factors or coexisting pathological conditions. Among the factors causing a substantial increase of the blood CgA concentration are: treatment with proton-pump inhibitors or H₂-receptor blockers, chronic atrophic gastritis (type A), impaired renal function, prostate cancer and BPH, and rheumatoid arthritis with high level of RF IgM. In addition, the sort of investigated biological material (whether it is serum or plasma) is of importance. There are also many conditions which may have a moderate or little influence on the concentration of CgA, among them are: inflammatory bowel disease (ulcerative colitis and Crohn's disease), deteriorating liver function, untreated essential hypertension, heart failure, hypercortisolism, pregnancy, and, in some subjects, ingestion of a meal. Proper assessment of the CgA results requires detailed knowledge about various factors, drugs, and pathological conditions influencing its concentration in blood.