<prompt> A boy comes with complains of vomiting, bloated abdomen and abdominal pain. He has history of attending ice-cream eating competition last night. He also past history of similar episodes following ingestion of milk and milk products. The likely cause :Pancreatic amylase deficiencyLactase deficiencySalivary amylase deficiencyFood poisoning  <response>: Ans. is b Lactase deficiency Ref. : O.P. Ghai, Pediatrics, 6e, p 110, 281 5e, p. 256, Nelson 17e, p 1268.History of ice cream ingestion and subsequent symptoms of vomiting, bloated abdomen, are characteristic findings of lactase deficiency.About lactase deficiency.Lactase is a disaccharidase present on intestinal epithelium brush border. It is used to digest lactose disaccharide.Lactase Deficiency SymptomsSymptoms arise after ingestion of food containing lactose e.g. milk.Symptom - Diarrhoea, vomiting, bloated abdomen.DiagnosisPresence of more than 12 percent of reducing substrate in fresh stool.Acidic stoolsAbnormal oral sugar tolerance test blood glucose rise of less than 20mgdl above fasting level with a disaccharide load of 2gkgBreath H2 excretion of more than 11 ppm.Enzyme assay on mucosal biopsies showing low levels of disaccharidases.Treatment - low lactose diet. 