TABLE 3.  Risk factors for gallstone formation
Factor Pigment stone Cholesterol stone

Demography
Race
Female sex
Age
Familial
Asian
?
+
Hemoglobinopathies
American Indian
++
++
++
Diet + Obesity (high calorie)
Weight reduction
High animal fats
Low fiber
Gallbladder stasis +
Total parenteral nutrition
++
Reduced meal frequency
Vagotomy
Pregnancy
Female sex hormones
Parity/fertility
Oral contraceptives
Estrogens
-
-
-
Early menarche
+
+
Associated disease Cirrhosis
Hemolytic anemia
Biliary infections
Cystic fibrosis
Ileal disease or loss
Diabetes mellitus
Drugs Clofibrate

++ = definite; + = probable; ? = questionable; - = unknown