A retrospective study of the usefulness of acid secretory testing.

BACKGROUND: Gastric analysis is useful for diagnosing and monitoring the control of hypersecretory conditions and to distinguish appropriate from inappropriate causes of hypergastrinaemia. Pentagastrin, used to measure maximal acid output (MAO), is no longer available in the USA.

METHODS: We examined the University of Pennsylvania Health System gastric analysis database, which includes demographic data, study indications, gastric analysis, and serum gastrin and secretin testing results according to referral indications, paying specific attention to discordant basal acid output (BAO) and MAO measurements.

RESULTS: One hundred and twenty-four gastric analyses were performed in 103 patients (42 males, mean age 47.5 years, 14 with prior acid-decreasing surgery). Recurrent ulceration or pain unresponsive to antisecretory therapy was the indication in 42 patients. Twelve were hypersecretory, including three each with isolated elevations of BAO or MAO. Hypergastrinaemia was the indication in 35 patients. Five were hypersecretory (four with Zollinger-Ellison syndrome), three had isolated MAO elevations and 16 were hypo- or achlorhydric, indicating appropriate hypergastrinaemia. Of the seven patients with isolated MAO elevations, two had clear benefit from the stimulated portion of the study (four additional patients had equivocal benefit).

CONCLUSIONS: Gastrin concentrations cannot be interpreted without knowledge of acid secretory capacity. MAO measurement has a small but significant benefit over measuring BAO alone.