Zollinger Ellison Syndrome

• Zollinger Ellison Syndrome (ZES) is a rare disorder causing excessive stomach acid secretion.
• It is primarily caused by gastrin-secreting tumors, known as gastrinomas, often found in the pancreas or duodenum.
• Common symptoms include severe abdominal pain, chronic diarrhea, and persistent heartburn.
• Diagnosis involves blood tests for gastrin levels and imaging studies to locate tumors.
• Treatment focuses on managing acid production with medication and surgically removing tumors when feasible.

What is Zollinger Ellison Syndrome?

Zollinger Ellison Syndrome (ZES) is a rare condition characterized by the formation of tumors, called gastrinomas, which produce excessive amounts of the hormone gastrin. This overproduction of gastrin leads to a significant increase in stomach acid secretion, resulting in severe and often multiple peptic ulcers in the stomach, duodenum, and even the small intestine. The constant high acid levels can cause persistent and debilitating digestive issues.

ZES is estimated to affect about 1 to 3 people per million annually, making it a very uncommon disorder. While gastrinomas are typically found in the pancreas or duodenum, they can also occur in other locations. Approximately 25-30% of ZES cases are associated with Multiple Endocrine Neoplasia type 1 (MEN1), a genetic disorder that predisposes individuals to tumors in several endocrine glands.

Zollinger Ellison Syndrome Symptoms and Causes

The causes of Zollinger Ellison Syndrome are directly linked to the presence of gastrinomas. These tumors, which can be benign or malignant, autonomously produce gastrin, leading to hypergastrinemia. This elevated gastrin then stimulates the parietal cells in the stomach lining to secrete large quantities of hydrochloric acid, overwhelming the stomach’s protective mechanisms and causing ulceration.

The Zollinger Ellison Syndrome symptoms often mimic those of more common gastrointestinal conditions, making diagnosis challenging. Patients typically experience persistent and severe abdominal pain, often unresponsive to standard ulcer treatments. Other common symptoms include:

• Chronic diarrhea, which can be severe and greasy (steatorrhea) due to acid inactivating pancreatic enzymes.
• Heartburn (gastroesophageal reflux disease – GERD) that is severe and persistent.
• Nausea and vomiting.
• Bleeding in the digestive tract, which may manifest as black, tarry stools (melena) or vomiting blood (hematemesis).
• Weight loss due to malabsorption and poor appetite.

These symptoms arise from the corrosive effects of excessive acid on the digestive tract lining and the impaired digestion of food.

Diagnosing and Treating Zollinger Ellison Syndrome

Zollinger Ellison Syndrome diagnosis and treatment require a multi-faceted approach. Diagnosis typically begins with blood tests to measure fasting gastrin levels. Persistently elevated gastrin levels, especially when combined with high stomach acid output, are strong indicators of ZES. A secretin stimulation test may also be performed, where secretin is injected, and gastrin levels are re-measured; a significant rise in gastrin confirms ZES.

Once biochemical diagnosis is established, imaging studies are crucial to locate the gastrinoma(s). These may include:

• Endoscopic ultrasound (EUS)
• CT scans or MRI
• Somatostatin receptor scintigraphy (SRS), also known as Octreoscan, which is highly effective in locating gastrinomas due to their somatostatin receptors.

Treatment for ZES focuses on two main goals: controlling acid secretion and managing the gastrinoma. Proton pump inhibitors (PPIs) are highly effective in reducing stomach acid production, alleviating symptoms, and allowing ulcers to heal. High doses are often required. Surgical removal of the gastrinoma is the preferred treatment when the tumor is localized and resectable, offering a potential cure. For metastatic or unresectable tumors, other treatments like chemotherapy, somatostatin analogs, or liver-directed therapies may be used to manage tumor growth and symptoms. Regular monitoring is essential for all patients with ZES to detect recurrence or progression.