肝内胆管小结石引起的肝内阻塞，能够引起局部胆汁淤积，但由于大量未阻塞部分可清除血中胆红素，血清胆红素水平不升高。但任何水平的胆道阻塞时，血清碱性磷酸酶都升高。
Here is an example of intrahepatic obstruction with a small stone in an intrahepatic bile duct. This could produce a localized cholestasis, but the serum bilirubin would not be increased, because there is plenty of non-obstructed liver to clear the bilirubin from the blood. However, the serum alkaline phosphatase is increased with biliary tract obstruction at any level.
