Serum gastrin and its response to secretin in hyperparathyroid patients.

In 36 patients with verified hyperparathyroidism (HPT), serum gastrin and its response to secretin was studied before and after parathyroidectomy. In most of the patients gastric secretion-basal acid output (BAO) and maximal acid output (MAO)--was also studied. Seventeen patients had increased serum gastrin values preoperatively and/or postoperatively. Most of the serum gastrin increases were moderate and all but one of the patients with values above 250 pmol/l had hypochlorhydria. Nine patients had a positive secretin test according to conventional criteria preoperatively or postoperatively, but showed no other signs suggestive of a gastrin-producing tumour. Most of the patients with a serum gastrin increase after injection of secretin had hypochlorhydria or achlorhydria. The BAO/MAO ratio was less than 0.6 in all patients. The results of this study do not support the view that primary HPT is often associated with a gastrin-producing tumour as part of a multiple endocrine adenomatosis (MEA type I), but indicate that the observed hypergastrinemia in HPT is almost exclusively related to hypo- or achlorhydria. The findings also give reason to doubt the value of the secretin test.