A number of structural and microscopic changes occur as the liver ages. (See also Overview of the Liver and Gallbladder for a discussion of normal function of the liver and gallbladder.) For example, its size and blood flow decrease. However, liver test results generally remain normal.
The ability of the liver to metabolize many substances decreases with aging. Thus, some drugs are not inactivated as quickly in older adults as they are in younger people. As a result, a medicine dose that would not have side effects in younger people may have dose-related side effects in older adults (see Aging and Drugs). Thus, medicine dosages often need to be decreased in older adults.
Also, the liver's ability to withstand stress decreases. Thus, substances that are toxic to the liver can cause more damage in older adults than in younger people. Repair of damaged liver cells is also slower in older adults.
The production and flow of bile decrease with aging. As a result, gallstones are more likely to form.
