Gastrin is a hormone that triggers the stomach to produce stomach acid. It is released into the blood as a result of undigested food entering the stomach. Elevated gastrin levels are a symptom of several diseases and conditions. The elevated levels may be the result of certain stomach conditions, or they may be caused by a type of malignant tumor that produces gastrin. A laboratory finding of elevated gastrin levels merits a thorough examination by a physician.
Hypergastrinemia is the medical term for high levels of gastrin. The causes of elevated levels can be grouped into two categories: Either a disease or condition is causing the body to produce extra gastrin, or a neoplasm is producing the extra gastrin. In either case, treatment is aimed not at reducing the level of gastrin but in correcting the underlying cause. If the underlying cause can be treated, the gastrin levels will return to normal.
Stomach conditions, such as gastric outlet obstruction and autoimmune gastritis, may cause high gastrin levels. Stomach distention will also raise the level of gastrin present in the blood. Elevated gastrin sometimes occurs as a side effect of other conditions. Pernicious anemia, rheumatoid arthritis, and diabetes mellitus sometimes present with laboratory findings of excess gastrin. Any condition that increases the pH level of the stomach, such as gastric ulcers, will cause excessive gastrin release as well.
Elevated gastrin levels are one of the three diagnostic criteria for Zollinger-Ellison syndrome. The syndrome is the combination of one or more gastrinomas, hypergastrinemia, and severe ulcer disease. Gastrinomas are tumors that excrete gastrin, causing elevated levels of the hormone. The tumors usually appear in the pancreas or duodenum. Up to 50 percent of gastrinomas are malignant.
In the absence of other conditions, hypergastrinemia is diagnostically indicative of one or more gastrinomas. Aside from Zollinger-Ellison syndrome, tumors sometimes develop as a result of hyperthyroidism or pituitary adenomas. Gastrinomas may also develop without any predisposing conditions. Elevated gastrin may also occur because of renal failure or colon cancer.
Gastrin levels are measured with a fasting blood test. Gastrin is released when food enters the stomach, so nonfasting blood tests have no value. Several drugs, such as protein pump inhibitors, opiates, and aspirin, can interfere with the testing of gastrin and cause incorrect readings. Prior to testing, the physician will direct the patient how far in advance of the test to discontinue use of these drugs.