<prompt> A boy comes with complains of vomiting, bloated abdomen and abdominal pain. He has a history of attending icecream eating competition last night. Ile also has a past history of similar episodes following ingestion of milk and milk products. The likely causePancreatic amylase deficiencyLactase deficiencySalivary amylase deficiencyFood poisoning  <response>: History of ice cream ingestion and subsequent symptoms of vomiting, bloated abdomen, are characteristic findings of lactase deficiency.Lactase deficiency -Lactase is a disaccharidase present on intestinal epithelium brush border. It is used to digest lactose disaccharide.Symptoms 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 the fresh stool.Acidic stoolsAbnormal oral sugar tolerance test blood glucose rise of less than 20mgd1 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. 