That's why I phrased it the way I did. He's correct in the primary vs secondary sense of the word wrt cholestasis.
Both PBC and PSC are primary in that they attack the bile ducts directly and this scarring, fibrosis and inflammation causes the impeded bile flow which leads to cholestasis. With other liver diseases, the liver lobules can become congested, enlarged and this compression of the internal sinusoids will tend to cause a more moderate, secondary form of intrahepatic cholestasis. And depending on where and how much the bile is impeded, the effect can be quite pronounced and is why we associate yellow skin with liver disease of course.
Also, the itching itself is caused by the backup of the bile (due to the flow blockage) and this forces the bile acids/salts into the blood stream along with the buildup of both conjugated and unconjugated bilirubin. It's these bile acids/salts that can accumulate under the skin that gets us to start doing our scratching thing - not that we can actually get at the source of the problem, but some of us seem to like a good scratching every now and then, like our friend "Pruritus Susan"!
Post Edited (bblbt) : 8/21/2014 12:03:55 PM (GMT-6)