This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hereditary Hyperbilirubinemia & Jaundice, Subject name: Medicine
[{'content': 'Obstructive jaundice is best detected by: \nSelect and explain. \nA. Increased ALP, B. Decreased ALP, C. Increased AST, D. Decreased AST', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Alkaline phosphatase is a marker of cholestasis i.e. elevation of ALP occurs in >90% of patients with cholestasis and suggests a reduction in bile flow. Because isozymes are found in the liver, bone, placenta, leukocytes, and small intestine, an elevated ALP is not specific for the biliary tract. ALP levels of greater than four times the normal are taken significant.', 'role': 'assistant'}]