Zollinger-Ellison syndrome
Introduction
Zollinger-Ellison syndrome (ZES) is a rare disorder characterized by the development of gastrin-secreting tumors (gastrinomas) in the pancreas and duodenum. These gastrinomas lead to an overproduction of gastrin, a hormone that stimulates the production of stomach acid. The excessive acid, in turn, leads to peptic ulcers, diarrhea, and other gastrointestinal symptoms.
Etiology
The exact cause of Zollinger-Ellison syndrome is unknown. However, approximately 25-30% of cases are associated with MEN1, a hereditary condition that causes tumors in the endocrine glands. In these cases, the gastrinomas are often multiple and are located in both the pancreas and duodenum.
Clinical Features
The clinical features of Zollinger-Ellison syndrome are primarily related to the hypersecretion of gastric acid. The most common symptoms include abdominal pain, diarrhea, and GERD. The abdominal pain is often severe and may be mistaken for other conditions such as gallstones or appendicitis. Diarrhea is typically persistent and may lead to weight loss. GERD, characterized by heartburn and regurgitation, is also common due to the excessive acid production.
Diagnosis
The diagnosis of Zollinger-Ellison syndrome is based on clinical features, laboratory tests, and imaging studies. The key laboratory test is the measurement of fasting serum gastrin levels. In ZES, these levels are typically markedly elevated. However, a definitive diagnosis requires a positive secretin stimulation test, in which gastrin levels fail to suppress following the administration of secretin. Imaging studies, including CT, MRI, and EUS, are used to locate the gastrinomas.
Treatment
The primary treatment for Zollinger-Ellison syndrome is the reduction of gastric acid secretion. This is typically achieved with proton pump inhibitors (PPIs), which are highly effective in controlling symptoms and healing peptic ulcers. In cases where the gastrinomas can be localized and are not widespread, surgical removal may be considered. However, surgery is not curative in most cases due to the presence of multiple tumors or metastasis.
Prognosis
The prognosis of Zollinger-Ellison syndrome varies depending on the extent of disease and the presence of metastasis. With appropriate treatment, the symptoms of ZES can be effectively managed, and the quality of life can be significantly improved. However, the overall survival rate is lower in patients with metastatic disease.