ulcers of the duodenum. Excessive HCl production also causes hyperperistalsis, a condition marked by excessive rapidity of the passage of food through the stomach and intestine and inhibits the activity of lipase, causing severe fatty diarrhea known as steatorrhea. Evenly the long-standing hyper-secretion of gastrin stimulate proliferation of the enterochromaffin like cells (ECL). These cells are found along the side the gastric lumen of the digestive tract. They play a main role in regulation of gastric secretion and motility when stimulated by nervous system. These cells in return will undergo progressive dysplastic changes starting with hyperplasia to neoplasia throughout the gastrointestinal tract. Diagnosis In many cases, gastrinoma is diagnosed based on the patient's history which is typically characterized by recurrent episodes of peptic ulcer disease or by severe reflux esophagitis and/or diarrhea or by acid-related symptoms which fail to respond to standard treatment regimens. To confirm the diagnosis of gastrinoma a series of blood tests must be made. One of those tests is the serum gastrin level, which is the most reliable test for patients with gastrinoma. The normal levels of gastrin are 150 pg/mL ( > 72.15 pmol/L); therefore elevated levels of > 1000 pg/mL (> 480 pmol/L) would establish the diagnosis of gastrinoma. Another test that can be conducted is the secretin stimulated test, which is useful in patients who have the sign and symptoms of gastrinoma but the gastrin levels are below < 1000 pg/mL. Usually, an Intravenous bolus consisting of secretin 2mcg/kg and is measured in 10 minute intervals up to 30 minutes total. Secretin, which is a hormone released from the duodenal S cells that induce the release of pancreatic bicarbonate (HCO3) that would neutralize the acidic environment due to high gastrin levels. Therefore, if the patient's level of gastrin remains consistently high indicating gastrin release due to tumor such as gastrinoma. Other commonly used tests to further confirm the diagnosis are CT scan of the abdominal area Somatostatin receptor scintigraphy which is used to identify the location of the tumor PET scan Endoscopic ultrasound if there are no signs of tumor metastases. Treatment Surgery is first line treatment in gastrinomas; however it often fails to be curative. Proton-pump inhibitors such as omeprazole. This group of medications suppress the acid secretion. H2-receptor antagonist similarly decrease acid secretion. Octreotide injections directly release somatostatin hormone that inhibits gastrin release. Chemotherapy. Prognosis Patients with gastrinomas that are also