Comparison of chromogranin A and pancreastatin levels in plasma of patients with pancreatic islet cell tumor.

The plasma levels of chromogranin A (CGA) in patients with islet cell tumor and plasma CGA responses to administration of a somatostatin analogue (Octreotide) in two of these patients were examined in comparison with plasma pancreastatin (PST) levels. There was a significant correlation between the fasting plasma levels of CGA and PST (r = 0.6, P < 0.001). Administration of the somatostatin analogue reduced the plasma concentrations of PST and CGA within 1 h, but the responses of CGA and PST to the analogue were not parallel in either patient. Thus, the suppressive effects of the analogue on the secretions of PST and CGA may be different. The results suggest the value of the PST and CGA assays used in this study.