Chapter 15 Cholelithiasis
INTRODUCTION
Description: Cholelithiasis is the formation of stones in the gallbladder or biliary collecting system. Most stones (80%) are the result of precipitation of supersaturated cholesterol. Women are three times more likely than men to form gallstones.
ETIOLOGY AND PATHOGENESIS
Causes: The metabolic alteration leading to cholesterol stones is thought to be a disruption in the balance between hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase and cholesterol 7α-hydroxylase. HMG-CoA controls cholesterol synthesis, whereas cholesterol 7α-hydroxylase controls the rate of bile acid formation. Patients who form cholesterol stones have elevated levels of HMG-CoA and depressed levels of cholesterol 7α-hydroxylase. This change in ratio increases the risk of precipitation of cholesterol as stones.
Risk Factors: Age, female gender, parity (75% of affected patients have had one or more pregnancies), obesity (15 to 20 pounds overweight 2-fold increase in risk, 50 to 75 pounds excess weight 6-fold increase in risk), estrogen use (oral), cirrhosis, diabetes, and Crohn’s disease. A family history of cholelithiasis in siblings or children results in a 2-fold increase in risk.
