The presence of
gastrin in pituitary tissue as well as
gastrin hypersecretion by some
pituitary adenomas have been documented using different methodological approaches. In the present study, serum
gastrin levels were measured in 93 patients with nonfunctioning
pituitary adenoma, i.e. a condition lacking a reliable marker of the disease. Elevated
gastrin levels (85-2, 180 ng/l; normal range: 15-80 ng/l) were found in 14/93 patients (15%), the highest values being observed in one patient with MEN I syndrome. In all but MEN I hypergastrinemic patient, a severe gastric
hypochlorhydria (Basal
Acid Output: 0.04 +/- 0.1 mmol H+/h) unresponsive to
pentagastrin (Maximum
Acid Output: 0.1 +/- 0.2 mmol H+/h) was seen.
Secretin injection caused
gastrin to increase in the patient with MEN I and in another hypergastrinemic patient. Antiparietal cells
autoantibodies were positive in 3/11 patients. No changes in
gastrin concentrations were found after administration of several agents usually employed in the evaluation of pituitary function, except a significant
gastrin reduction after
octreotide injection. In two hypergastrinemic patients who underwent pituitary adenomectomy, the high
gastrin levels did not change after surgery. Finally,
gastrin was undetectable in the
culture media of 15
pituitary adenomas surgically removed from both normo- and hypergastrinemic patients and immunocytological studies of
tumor cells did not show any
gastrin staining. In conclusion, although in patients with
pituitary adenomas serum
gastrin evaluation is indicated in order to document the presence of a MEN I syndrome, the present data show that high
gastrin levels cannot be taken as a specific marker of nonfunctioning
pituitary adenomas unless the peripheral origin of hypergastrinemia is excluded.