American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What does basal acid output greater than 15 mEq/hr suggest in the context of Zollinger-Ellison syndrome?

1. Normal gastric function

2. Possible gastrinoma

3. Peptic ulcer disease

4. Hypochlorhydria

The correct answer is: Possible gastrinoma

Basal acid output greater than 15 mEq/hr is a significant indicator in the context of Zollinger-Ellison syndrome, which is characterized by excessive gastric acid secretion due to gastrin-secreting tumors, commonly known as gastrinomas. In Zollinger-Ellison syndrome, the elevated levels of gastrin stimulate the parietal cells of the stomach to produce acid, leading to a higher-than-normal basal acid output. In this clinical scenario, a basal acid output exceeding the threshold of 15 mEq/hr strongly suggests the presence of a gastrinoma. This is a hallmark feature of the syndrome, as normal gastric function or peptic ulcer disease typically does not result in such high levels of acid production. Instead, they may have normal or transiently elevated acid levels not consistently hitting the 15 mEq/hr mark. Hypochlorhydria, or low gastric acid production, would be inconsistent with this finding as well, since it would suggest diminished gastric secretion rather than the hypersecretion seen in gastrinomas. Thus, the significant elevation in basal acid output is a critical diagnostic criterion for identifying gastrinomas associated with Zollinger-Ellison syndrome.