How is Zollinger-Ellison syndrome diagnosed?

Zollinger-Ellison syndrome is characterized by gastrin-secreting tumors (gastrinomas) that lead to excessive gastric acid production, resulting in recurrent peptic ulcers and gastric acid-related symptoms. The diagnosis of Zollinger-Ellison syndrome primarily involves measuring gastrin levels, particularly after fasting, since high levels of gastrin are indicative of the syndrome.

The fasting gastrin test helps establish the presence of hypergastrinemia, which is a hallmark of this condition. Additionally, the secretin test is utilized in cases where the diagnosis is uncertain or to distinguish gastrinomas from other causes of elevated gastrin levels. Secretin normally inhibits gastrin secretion, so in patients with gastrinomas, administering secretin leads to an inappropriate increase in gastrin levels, further supporting the diagnosis.

Other testing methods, like gastric emptying studies or upper endoscopy, may be useful in assessing gastric function or identifying ulcers, but they do not definitively diagnose Zollinger-Ellison syndrome. These tests focus on other aspects of gastric health rather than directly measuring gastrin levels or evaluating for gastrin-secreting tumors.