Which hormone’s elevated blood level is characteristic of Zollinger-Ellison syndrome?

• A. Trypsin
• B. Pepsin
• C. Gastrin
• D. Cholecystokinin-pancreozymin

Answer: (C)

Zollinger-Ellison syndrome is driven by a gastrin-secreting tumor, a gastrinoma, which pushes gastrin levels in the blood well above normal. This hormone stimulates the stomach’s parietal cells to produce large amounts of hydrochloric acid, leading to gastric acid hypersecretion and the characteristic recurrent peptic ulcers and diarrhea. Among the options, only gastrin is the regulator that becomes markedly elevated in this condition; the other choices are not hormones that drive acid production in this scenario—trypsin and pepsin are digestive enzymes, and cholecystokinin-pancreozymin is a different gut hormone not specifically elevated in Zollinger-Ellison. In practice, very high fasting gastrin levels (often with supportive tests like a secretin stimulation test) point to gastrinoma as the cause.