Liver Function Tests (LFTs) Explained Clearly by

well welcome to another MedCram video
we’re going to talk about cholestasis here in the liver function tests so
picking up on the theme that we were talking about before when we talked
about AST ALT albumin and the protime we were talking about the actual liver
parenchyma 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 there’s also that 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 is to help with digestion of fats but also to get
rid of some products specifically Heme 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-glutamyl transferase (GGT) 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 in the spleen in 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 okay 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 are aware are intrahepatic and the
ducts outside our extra hepatic 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 hepatic or in the intra hepatic ducts that are
supposed to get rid of the bilirubin and the bile acids what’s going to happen is
the conjugated bilirubin is going to build up in the blood and the
unconjugated bilirubin is going to build up in the blood and you’re going to 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 bilirubinurea
not emia but urea that is the presence of conjugated
bilirubin in the blood you will not see unconjugated bilirubin being passed
through the kidney so if you see bilirubin 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 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 along the intra or extrahepatic
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 you have
an elevated alkaline phosphatase you’re not exactly sure what’s causing it is it
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
those 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 GGT or
otherwise known as Gamma-Glutamyl Transferase now this is pretty good
because you do see an increase in GGT 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-Glutamyl Transferase and if it is low if
the Gamma Glutamyl Transferase 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-Glutamyl 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 going to 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
DIC 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
Gilbert’s disease it looks like Gilbert’s but it’s pronounced
Gilbert’s disease believe it or not this condition which is autosomal dominant 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 glucuronosyltransferase 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 going to 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 going to pass from the blood into the kidney and you’re going to pick up
hyperbilirubinemia gaited bilirubin in 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

100 Replies to “Liver Function Tests (LFTs) Explained Clearly by”

  1. Best lecture I have ever seen on liver tests. I now show it to all my health care students when we study the liver. Outstanding job sir!

  2. Outstanding! As a practicing PA, I always appreciate good review. These are wonderful. Please keep them coming!!

  3. Thanks for these lectures! Can you do one explaining the A-a gradient, especially with patients who aren't on room air. Thanks!

  4. Thank you so much. You make it easy to understand. I love your drawings and your voice. My GI doc does not draw as well. He explains well and is on my side. I'm at the top of the list for a new liver. 3points on Monday towards my MELD score!!!!!

  5. You make it so easy to understand. 11 minutes of listening and watching this video was better than an hour and a half of an egotistical lecture. I will look for more to reinforce other lectures.

  6. You by far the best lecturer on Youtube for pathology. I love your work. Clear and accurate information. Keep it up! 

  7. Hello, 
    i thought that the urine got its concentrated yellow colour from some bilirubin that passed through. Wouldn't that make urine bilirubin levels a bit high? 

  8. Thank you sooooo much for doing these lectures. I referred to your lectures while I was working on my NP degree. Now I am working in Gastroenterology and your lectures are really helping me to pull all of this info together! I really reallllly appreciate you for sharing your knowledge and making the subject matter understandable in a very unique way. I don't know if you will read this but thanks for all you do!

  9. Thank you for this video, I am worry becouse I have "cyst" in the liver; I have a test in the emergency room when they are looking for some apendicitis; when I when to my family dr. she said is not important. Can you explain me why I have this ( what I am eating o medicine take it to cause it) and how to fix it without surgery? I really apreciate it. thank you

  10. To day i stretched and something cracked now something in my lower chest area hurts i put some ice on it but it still hurts

  11. thank you for making this video.. it helps me a lot on my exam tomorrow.. may I ask if you could make a lecture about the bilirubin metabolism?? please.. thank you!! more powers!

  12. If there is a blockage in the intra and extra hepatic ducts, and the conjugated bilirubin is excreted through these, wouldn't there be less conjugated bilirubin floating around the bloodstream and not more? Thank you 🙂

    Also if you would ever consider getting someone (or perhaps yourself) to transcribe your lectures for subtitles, myself and the whole deaf medical community would greatly appreciate it! Thank you 🙂

  13. You are a very, very good speaker. Thank you very much because, thanks to you, this has finally clicked!

  14. I had jaundice almost 2 years from now i went for a proper medical checkup and did every thing to cure it . I avoided oily and fatty foods. I only ate salads. I took every medicine until the tests showed Normal. But then when I repeated the test a month after it again showed bilirubin out of the normal range.This hapenned many times that year and in the end Doc. said that" you have Gilberts Syndrome…and all of this is normal for people wth GS." For now I am assuming that I have Gilberts synd. Moreover, what i realize is that the bilirubin level in my blood increases whenever i have an illness like fever or headache ,stress(during exams),during fasting (in the month of ramadhan).Now i want to know if I really have GS or not and i will be so glad if You help me in this.

  15. As an emergency medicine PA-C, with plans to go into academia later in my career, I appreciate your videos for review of general medical knowledge. The videos are engaging and the material is very well explained. I've directed PA students of mine to your videos to help them in their studies and to help understand laboratory and physical exam findings while on their clinical rotations with me. Keep up the great work! Your videos are invaluable to me.

  16. These are very helpful for me as a PA student. Videos help me understand much more than books do, so this is perfect. Nice and clear.

  17. Thanks for the video, its great and i have a clear concept on LFT now.

    just wanted to make some corrections. If i am wrong let me know:

    -gilbert syndrome is autosomal recessive (not dominant)
    -Extravascular hemolysis causes an increase in Indirect bilirubin. (not intravascular. intravascular causes hemoglobinemia and hemoglobinuria. extravascular hemolysis results in breakdown of the heme into unconjugated bilirubin)

  18. please I want to ask my Left AST value is 19 range is 10- 50 U/L and the ALT 9(L) 10- 50 U/L what is that suppose to mean I'm Chronicaly effected which HBv and takin medication thank you

  19. Ref. range of my AST is 38 , ALT is 55 and AFP is 15.
    Based on the lab. test – I'm Hepatitis B e Antigen Reactive
    By March 28, 2015, I was scheduled for my blood test enterpretation with my doctor.
    Anyone can help me to understand these? really needs your help.

    (sorry for my bad english)

  20. Great Video. Thanks. I have a question if I may. What if ALK Phos is low. What might that indicate?

  21. Hello,

    I know you can't diagnose anything, but I would really respect your opinion.

    My ALT is 113 (normal is 10-63) AST and ALP normal.

    Had an ultrasound done, came back showing a mildly enlarged spleen at 13.47cm, and my liver is showing fatty liver. It also showed bile ducts were normal.

    All my CBC is normal.

    My Total bilirubin is 3.2 (normal is 1.5), and direct being 0.3 (normal). So that means my indirect is causing my high bilirubin.

    LDH was actually a little low at 100 (normal was 120-250).

    Since hemolysis is pretty much ruled out, do you think this is a case of Gilbert's Sydrome?

  22. Do I need to fast before a liver function test? I fasted for 12 hours before a liver function test 3 weeks ago and my ALT was 57. Today I didn't fast and my ALT was 114! Is this because I didn't fast? I haven't had any alcohol, and am eating a very clean diet for the last 3 weeks.

  23. See the whole series at along with other top quality videos including reviews in pulmonary, cardiology, infectious disease, and hematology!

  24. all my liver enzymes are 4 times elevated than normal , i have done most of the tests under the planet -ct abdo ,fibroscan , ultrasound, gastroscopy and colonoscopy they are normal, all blood tests are normal including cholestrol ,serum studies and antibibodies test any idea whats the cause for it , i rarely drink alcohol

  25. i always find a difficulty in understanding these stuff BUT you made it easy for meee thank you so much 🙏 .. Keep it up 💪

  26. could you please do more on CXR's? I am by myself on ICU and Some nursing homes, still having difficulties in reading. If you please do for chest CT's and abdominal CT's.

  27. My bilirubin is high at a 2.0 they want me to come and re test in 2 weeks. Should I be worried??

  28. Thanks for explaining LFT test. I am doing reserch on Liver detox, Which test can make me clear that my liver detox is working or no?
    Can you or anyone please help me.

  29. My bilirubin is slightly elevated. I have early alcoholic cirrhosis its currently 1.9 can my liver heal and can i lower it?

  30. I just found I got low liver function but the Dr wasn't to clear im confused can some body explained. Not the Dr on the video but the Dr who read my blood results

  31. My ALT is 32 and my AST is 24.. But my ALP is 137.. Apparently they didn't test my GGT.. Should I be concerned about the ALP being elevated?

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