Final answer:
Paget's disease of bone is the most common cause of asymptomatic isolated elevation of alkaline phosphatase in elderly patients, due to the disorganized bone remodeling characteristic of this condition.
Step-by-step explanation:
The single most common cause of asymptomatic isolated elevation of alkaline phosphatase in an elderly patient is often Paget's disease of bone. Alkaline phosphatase (ALP) is an enzyme found in several tissues, including the liver and bones. While increased levels can indicate acute liver damage, it's also associated with bone remodeling, which is pertinent to conditions like Paget's disease. In Paget's disease, there is excessive bone breakdown and formation, leading to disorganized bone remodeling and therefore an elevation in ALP.
Elderly patients with asymptomatic isolated elevation of ALP should be evaluated for Paget's disease, as it is a common condition in the elderly that can elevate ALP without causing other symptoms. However, an increase in alkaline phosphatase can also be indicative of other health issues such as biliary obstruction, cholestasis, or infiltrative liver diseases, which require different diagnostic measures and management.