By Adem Lewis /

Welcome to another MedCram video
we’re gonna talk about cholestasis here and liver function tests so picking up
on the theme that we were talking about before when we talked about ast alt
albumin and the pro time we were talking about the actual liberal per n comma
itself next we want to talk about cholestatic what does that mean well we
talked about the liver and specifically there is a gallbladder and the mat is
connected with a cystic duct and there is a then of common bile duct and that
dumps into the intestines and the purpose of this is a two-fold help with
digestion of fats but also to get rid of some products specifically Hema products
and that’s what we’re going to talk about next we’re going to talk about
things like the alkaline phosphatase the gamma gluten will transfer a serum
bilirubin bile acids things of that nature so let’s go through that very
carefully okay so let’s draw a picture here of
what’s going on schematically here is our liver this is schematic and we’ve
got the red blood cell so we’ve got blood over here which lasts for about a
hundred and twenty days so here’s our red blood cell and it gets broken down
after a while and the spleen and the reticulo-endothelial system and what it
gives up is something we call unconjugated or another way of saying
this is indirect this way its measured bilirubin and that goes to the liver and
it gets converted it’s a big enzyme in there and it gets converted and excreted
as something different called conjugated or direct bilirubin and there’s actually
ducts in here those ducts that are inside the liver just so you’re aware
are ah hepatic and the Ducks outside are
extrahepatic now the kidney also fits into this in
that the conjugated bilirubin and not the unconjugated bilirubin can be
excreted through the kidney so what do I mean by that if for some reason there is
a blockage here in the extra paddock or in the intra hepatic ducts that are
supposed to get rid of the bilirubin and the bile acids what’s gonna happen is
the conjugated bilirubin is going to build up in the blood and the
unconjugated bilirubin is gonna build up in the blood and you’re gonna be able to
check it with a blood test however only one of these things and that is
specifically the conjugated bilirubin because it’s conjugated it’s more
water-soluble is going to be able to make it through the blood and actually
get excreted out through the kidney and so if you see Billy Ruben urea not emia
but urea that is the presence of conjugated bilirubin in the blood you
will not see unconjugated bilirubin being passed through the kidneys so if
you see Billy Ruben in the urine that means you must have conjugated bilirubin
in the blood and that means either intrahepatic or extra hepatic
obstruction okay so with that let’s start going through this methodically
the first test that I want to talk about is the presence of alkaline phosphatase
ALK phos we also got out Foss you’ll see this on a regular complete metabolic
panel it has a low specificity for cholestasis because there are three
things that can increase the level of alkaline phosphatase the first thing is
cholestasis and that’s exactly what we’re talking about here any kind of
blockage all along the intra or extra hepatic area is
cholestasis and that can increase the alkaline phosphatase it’s what we call
an inducible enzyme which means it takes a little while for it to happen it’s not
going to happen right away but it will happen the second thing that can cause
an increase in alkaline phosphatase is pregnancy the third thing that can cause
an increase in alkaline phosphatase is bone disease specifically bone growth so
where would we see something like that in like for instance Paget’s disease
where you have increased bone turnover also in blastic not lytic type of
cancers what are the blastic type of cancers prostate and breast can cause
blastic lesions so cholestasis is just one of those things so if we have an
elevated alkaline phosphatase you’re not exactly sure what’s causing it is a
cholestasis pregnancy or bone growth but cholestasis is one of those things and
if we see a blockage here you will get an increase in alkaline phosphatase but
it’s got a low specificity for cholestasis the biliary duct tell cells
is what increases it you can see an increase in most types of liver damage
as a result of that and high levels are seen in cholestasis so because of that
uncertainty there’s another test called egg GGT or otherwise known as gamma glue
Tamil trance race now this is pretty good because you do see an increase in
GG T in cholestasis but you don’t see it in bone disease so I’ll put a big X
there you do not see it in bone disease just cholestasis so the way this is used
is if you have a patient with a high alkaline phosphatase and you want to see
whether or not this is GI related or liver related you can get a gamma glue
Tamil transferase and if it is low if the gam of the Tamil transfer ace is low
that means it’s not from the liver if it’s high then that means it probably is
from the liver interestingly alcohol EtOH
can also make gamma glue Tamil transferase elevated okay so let’s take
a look at our chart again you can see here that if we have a lot of breakdown
of blood products we’re gonna get a lot of unconjugated bilirubin and so you can
see that indirect bilirubin and the way you would check for that is by checking
a total bilirubin on the blood test and also checking for a direct bilirubin and
the difference between these two is going to be your indirect bilirubin if
you see that that is high it can either mean that you have a lot of breakdown of
blood products so where would we see that we would see that in di see
intravascular hemolysis that type of thing or it could be the inability to
convert unconjugated bilirubin to direct conjugated bilirubin and what are one of
those these diseases well the most common disease is this thing called G
Bears disease it looks like Gilbert’s but it’s
pronounced G Bears disease believe it or not this condition is present in up to
5% of the general population and you would see an increase in the
total bilirubin up to about 3.0 milligrams per deciliter and this is a
result of decreased expression of this enzyme gluten will transfer ace which is
the important step in the conversion of indirect bilirubin to direct bilirubin
now if you get a problem anywhere along here so liver damage drug damage in
ability to excrete the direct conjugated bilirubin after it’s been processed back
into the biliary ducts this is the intrahepatic ducts or in the extra
hepatic portion let’s say you’ve got a tumor of the pancreas or you’ve got a
stone blocking the common bile duct you will get an increase in this conjugated
direct bilirubin and it will back up like we said into the blood not only
that you’ll also see an increase in unconjugated or indirect bilirubin so
how do you tell if that’s what’s going on well in this situation because the
blockage is here you’re gonna see at least 50% of the
bilirubin in the blood being of the direct type so if you check a total
bilirubin and a direct bilirubin you’ll see that the direct bilirubin is more
than 50 percent of the total bilirubin that lends you to believe that there is
some either intrahepatic or extra hepatic obstruction causing this
cholestatic jaundice now because direct bilirubin is building up in the blood
and because it is more water-soluble it’s gonna pass from the blood into the
kidney and you’re gonna pick up hyperbilirubinemia the blood okay so with this background
in the next lecture what we’re going to talk about is the type of patterns that
you would see in actual diseases we’re going to talk about acute hepatitis
chronic hepatitis and cholestatic liver disease so join us for the next
lecture thanks very much you

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