Gastrinomas are tumors characterized by secretions of large amounts of gastrin, a hormone that increases the amount of acid released by the stomach. They are most commonly associated with Zollinger-Ellison syndrome (ZES), a rare gastroenterological disorder. This disorder is more commonly referred to as peptic ulcer disease and is also sometimes called gastrinoma because of its close association with these tumors.
Most often, gastrinomas occur in the duodenum and the pancreas, though they may also occur in the pituitary gland and the hyperfunction of the parathyroid gland. About 66% are malignant, often spreading to the patient’s liver. In addition, due to the increased production of acids by the tumors, patients with ZES develop large numbers of severe ulcers. These are mostly located in the stomach or the duodenum.
In the early stages of ZES disease, peptic ulcers are the most typical symptom. After ZES has become more established in the body, these ulcers start to cause more problems for the patient and become more difficult to treat with anti-ulcer therapy. At this point, additional symptoms such as diarrhea and abdominal pain may develop. In fact, diarrhea is the most common symptom of gastrinomas.
A blood test is usually necessary for diagnosing gastrinomas. This test is designed to determine the amount of gastrin in the patient’s blood. A level of over 200 picograms per milliliter (pg/mL), which is four to ten times more than the normal level, is a strong sign. In severe cases, patients have gastrin levels measuring 450,000 pg/mL.
If the test does not show high levels of gastrin in the patient’s blood, a physician may instruct the patient to eat specific foods or may inject the patient with certain substances in order to create a response. A secretin injection test is the most common method used. This test almost always creates a response in patients with gastrinomas.
Gastrinomas may be treated with surgery, though they are difficult to find. In fact, the tumors in 10 to 20% of patients go unseen during surgery. In these cases, the gastrinomas may not be found until they have metastasized and caused additional symptoms.
In some cases, gastrinomas may also be treated with anti-ulcer medication. A patient taking medication to successfully control them will need to stay on the medication for the remainder of his or her life. Otherwise, ulcers will recur. In addition, anti-ulcer medications do not heal gastrinomas, and for many patients, they are not an effective long-term treatment.