Ans. is 'c' i.e., Basal acid output (BAO) less than 15mEq/litre BAO is usually more than 15 meq/h in pts with gastrinoma (> 80% cases).A gastrinoma is a neuroendocrine tumour that secretes gastrin.The chronic hypergastrinemia leads to - gastric acid hypersecretion - peptic ulcer disease as well as diarrhoea.Symptoms of gastrinoma (Zollinger-Ellison Syndrome)Abdominal pain (70-100%)Diarrhoea (37-73%)0 GERD (30-35%)Diagnosis of Gastrinoma or Zollinger Ellison Syndrome.The first step in evaluation of a patient suspected of having ZES or gastrinoma is to obtain a fasting gastrin level.Virtually all gastrinoma patients will have a gastrin level > 150 to 200 pg/ml (normal <150 pg/ml)The next step in establishing a biochemical diagnosis of gastrinoma is to assess acid secretion. Up to 90% gastrinoma patients may have a BAO of > 15 meq/h (normal < 4 meq/h)A BAO/MAO ratio >.6 is highly suggestive of ZES, but a ratio of <.6 does not exclude the diagnosis.Gastrin provocative tests are helpful in patients with indeterminant acid secretory studies. Three provocative tests are used.Secretin stimulation test*Calcium infusion study*Standard meal test*In each of these tests gastrin level is measured after the stimulus i.e. secretin, gastrin, standard meal.Among these tests secretin test is the most specific and sensitive test*, (there is > 200pg increase in serum gastrin level within 15 minutes)Also know this important point about the diagnosis of gastrinoma.If in a patient - the pH is <2.0 the gastrin level will determine further course gastrin level > 1000 pg/L - diagnosis of gastrinoma is established gastrin level < 1000 pg/L - determination of BAO and secretin provocative test is required.