Pancreastatin plasma levels in patients with primary hyperparathyroidism

Pancreastatin, a C-terminally amidated peptide derived from chromogranin A, is known to inhibit insulin secretion, pancreatic enzyme release, and gast ric acid secretion. It also inhibits parathyroid hormone (PTH) secretion in animals. The physiologic and clinical relevance of pancreastatin in humans , however, is not known. Because pancreastatin has been found in parathyroi d adenomas, we investigated the plasma levels in patients with primary hype rparathyroidism (pHPT). Thirteen patients operated on for solitary parathyr oid adenoma were investigated. Plasma levels of pancreastatin and serum lev els of ionized calcium and intact PTH were measured before and 6 weeks afte r operation. In 10 patients the levels were also monitored before and 60 mi nutes after adenoma excision. The adenomas were investigated for pancreasta tin immunoreactivity by immunocytochemistry. The median weight of the excis ed parathyroid adenoma was 0.64 g (range 0.07-2.00 g). Cells displaying pan creastatin immunoreactivity were present in all adenomas examined and varie d in number and immunostaining intensity among and within the adenomas. Int raoperatively, after adenoma excision the levels of PTH and pancreastatin d eclined (p < 0.01), whereas the levels of ionized calcium did not change (p = 0.96). At the 6-week follow-up the levels of ionized calcium and PTH had decreased compared to the preoperative levels (p < 0.01), and all patients were normocalcemic. In contrast, the pancreastatin levels were not changed (14.5 +/- 6.1 pmol/L preoperatively vs. 12.8 +/- 11.2 pmol/L 6 weeks posto peratively; p = 0.12). In patients with pHPT, pancreastatin is likely to be produced by the parathyroid adenoma. The changes in pancreastatin levels i mmediately after surgery warrant further investigation.