Why phase 2 reactions are relatively preserved despite the decline in hepatic mass is unclear. It may be because of compensatory extrahepatic conjugation. The older liver may be less responsive to enzyme induction by some agents. The decreased hepatic blood flow, together with decreased hepatic weight, accounts for decreases in hepatic drug elimination of some compounds in the elderly. The liver's ability to withstand stress may decrease with age.
Many hepatotoxic drugs cause more severe injury in livers of older persons.
Hepatic regeneration is delayed but not greatly impaired with age. In aging rats, the capacity for hepatic regeneration remains intact, but the rate of regeneration decreases. The regulation of regeneration, however, is poorly understood. Postoperative morbidity and mortality, however, are usually not due to liver failure but rather to extrahepatic complications of the surgery. Gallbladder Various age-related changes in bile flow and bile acid secretion occur with age.