Liver Disease: Introduction and Commonly Used Liver Test

by Carlo Raj, MD

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    00:00 Hello, welcome to hepatobiliary diseases. Here, our topic at first will be viral hepatitis.

    00:09 Remember, that when we discuss hepatitis, there could be many, many causes as we go through our topic of hepatitides. At first it will be viral, but it could be autoimmune, it could be alcohol, it could be many causes. Do not always assume that it's viral. Let's begin. The liver test that you should be familiar with known as the liver function tests include the following, in hematology we talked about bilirubin quite a bit and here we'll talk about bilirubin as being part of prejaundice or prehepatic jaundice, hepatic jaundice, and posthepatic jaundice. Here, with bilirubin accumulating, we're not exactly sure as to what part of bilirubin metabolism could be affected. What do you mean Dr. Raj? Watch. Say that you brought bilirubin, unconjugated type, an indirect is what, is what we use clinically, and you bring this lipid-soluble substance to the liver. With the chaperon, the albumin then drops it off. Obviously the 1st step here by the liver is to make sure that it conjugates it, correct. What does conjugate mean to you? It means your turning something that's lipid-soluble into water-soluble and why is this objective so important, because we're trying to at some point get this bilirubin out into excretion and in order for you to get bilirubin into the urine, you must conjugate it at some point in time. My point is this, when you have liver disease, may be perhaps the enzymes have been affected. What enzyme is responsible for conjugation? The operative word always is going to be called glucuronidation. And let that be UDPGT or UGT, uridine glucuronosyltransferase. Without going into that type of detail, if the liver is damaged sufficiently and the enzymes are not working properly, then what component or what faction of your bilirubin are you then noticing? Good, the unconjugated bilirubin. Or let's say that there was enough damage to the liver that now at this point the entry point into bile has been blocked, but remember bilirubin is part of your bile as well. So, therefore now, you could get conjugated; however, the type of bilirubin that you're looking for laboratory-wise could be conjugated. So what's the point and what are you paying attention to on your boards and your words? You can have a mixed picture of bilirubin or called mixed jaundice when you have liver disease. Keep that in mind. If that is not clear, make sure that you go back and take a look at proper and full bilirubin metabolism so what I have just discussed with you medically, clinically makes a lot more sense. Next, my topic is liver function tests. What if the liver is damaged sufficiently enough where the liver inadequately does not put out albumin, hmmm.

    03:24 Welcome to simplex cirrhosis. Anything that causes end-stage liver disease or if there's sufficient liver damage, there is every possibility that albumin could be diminished, hmm. What does albumin contribute physiologically in your circulation? What part of your strong forces? Good, oncotic pressure. Thus, if albumin is not present, oncotic pressure drops. Where is my fluid now escaping into? Into tissue. There're 2 coag tests or coagulation tests. You notice that is a platelet test, right. What's the platelet test that you're extremely familiar with or should be? That's bleeding time. In hemodynamics, we talked about platelets. I'm not going to bring that up here, but either platelet dysfunction or quantitatively you have thrombocytopenia, then the bleeding time will be affected. Here, however, the coagulation factors that you should be familiar with include, well from the liver, what are you synthesizing, 2, 7, 9, and 10, the vitamin K-dependent factors, on one end pro-coagulation, and what are the 2 anticoagulation factors that the liver produces, protein C and protein S. From henceforth whenever you think about the liver, remember there are pro- and anticoagulant factors that are in fact being secreted from it, correct. Next, clinically speaking, which of the 2 tests are you going to measure of your coagulation to tell you that the liver may or may not be functioning properly? It's PT, prothrombin time; INR, international normalizing ratio. What is the PT that you want to know in terms of the actual time? 11 to 15 seconds, you know that for your boards you'll be in good shape. Thus, if the liver is not functioning properly, the synthesis of your coagulation factor drops, what then happens to your PT? Increases. If ALT, this is your alanine or alkaline, alanine type of aminotransferase, so you have the 2 transaminases, ALT and AST, and the ratio here do become very important. Since our topic in this section is going to move into viral hepatitis, would you please be able to tell me which one of these transaminases will be elevated more so? Would it be ALT or AST in viral hepatitis? Good, ALT. Just to make sure that we're clear and to have a little bit of fun with this, I want you to toast to AST. Toasting what? Alcohol, so whenever you have alcohol-induced hepatitis, there the AST will be increased versus ALT 2:1 ratio, continue. When does alkaline phosphatase come into play? And do not confuse ALP with ALT. ALP, alkaline phosphatase, would have come in to consideration if the biliary tree has been affected. Obviously, the liver and the biliary tree are 1 unit. You cannot separate one from the other. If there is enough damage that's taking place to the liver, understand that you are then going to affect your bile or biliary canaliculi and so therefore may cause damage or injury to the biliary system and therefore increasing ALP. Just to make sure we're clear, would you tell me as to what other set of diseases under a different type but still ALP would be used for? Obviously bone disease. Now the 2 types of liver function are PT and albumin. So those are the two that you definitely want to focus upon but absolutely understand that each one of the components that we're dealing with here will play an important role so that you can diagnose your patient properly. The others only signify altered function and do not correlate with overall synthetic activity of the liver. So, of all of these, the two that actually give you proper functioning liver include PT and albumin.

    About the Lecture

    The lecture Liver Disease: Introduction and Commonly Used Liver Test by Carlo Raj, MD is from the course Cirrhosis – Liver Diseases.

    Included Quiz Questions

    1. Increase in unconjugated bilirubin
    2. Increase in conjugated bilirubin
    3. Increase in PT
    4. Increase in APTT
    5. Increase in gamma-glutamyl transferase
    1. Unconjugated bilirubin
    2. Aspartate transaminase (AST)
    3. Alanine transaminase (ALT)
    4. Alkaline phosphatase
    5. Prothrombin
    1. Albumin and PT
    2. AST and ALT
    3. Conjugated bilirubin and unconjugated bilirubin
    4. Gamma-glutamyl transferase and ALT
    5. Alpha-fetoprotein and AST
    1. ALT
    2. AST
    3. Gamma-glutamyl transferase
    4. Alpha-fetoprotein
    5. 5-deoxynucleotidase
    1. 2:1
    2. 1:2
    3. 3:1
    4. 3:2
    5. 4:1
    1. Alkaline phosphatase
    2. AST
    3. ALT
    4. Alpha-fetoprotein
    5. Prothrombin time

    Author of lecture Liver Disease: Introduction and Commonly Used Liver Test

     Carlo Raj, MD

    Carlo Raj, MD

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    By S C. on 08. August 2021 for Liver Disease: Introduction and Commonly Used Liver Test

    very good lecture. high yield. excellent coverage of the topics.

    very practical
    By Luis R. on 04. May 2020 for Liver Disease: Introduction and Commonly Used Liver Test

    very good teacher, brings a lot of practical information. nice vid

    nothing great
    By Harsh Y. on 04. May 2019 for Liver Disease: Introduction and Commonly Used Liver Test

    wached pathoma and then went for this . explaiation not up to the mark

    Best lecturer on this site.
    By Iftakhar A. on 06. March 2018 for Liver Disease: Introduction and Commonly Used Liver Test

    He is the best lecturer on this site.His style of teaching is very powerful.He is not too fast, he knows when to pause for a second, when to repeat a word.Thank u Sir.