Liver Function Tests (LFTs) interpretation | COMPLETE GUIDE
Summary
TLDRThis video script offers an in-depth look at liver function blood tests, explaining the significance of each component, such as ALT, AST, ALP, GGT, bilirubin, albumin, and prothrombin time. It teaches viewers how to interpret these tests to diagnose liver damage, cholestatic damage, and the liver's synthetic function. The script also discusses the causes of jaundice and how to differentiate between pre-hepatic, hepatic, and post-hepatic conditions, providing valuable insights for medical professionals and patients alike.
Takeaways
- 📌 Liver Function Tests (LFTs) are used to assess liver health and diagnose liver conditions.
- 🔍 ALT and AST are markers of liver cell damage; ALT is more liver-specific compared to AST.
- 📈 An ALT/AST ratio can help differentiate types of liver disease, with ALT > AST usually indicating liver disease and AST > ALT suggesting liver cirrhosis or acute alcoholic hepatitis.
- 🚑 High AST levels can also be due to non-liver causes such as myocardial infarction or rhabdomyolysis.
- 🌐 Common causes of liver damage include alcoholic fatty liver disease, non-alcoholic fatty liver disease, viral hepatitis, drug toxicity, autoimmune hepatitis, and liver cirrhosis.
- 🧪 ALP and GGT are indicators of cholestatic damage, with ALP found in bile ducts and bone, and GGT specific to bile duct cells.
- 🔎 Comparing ALT to ALP levels can help determine the type of liver injury: hepatocellular or cholestatic.
- 🟡 Bilirubin is a hemoglobin breakdown product, and its levels can be raised in certain diseases, affecting the appearance of the skin and eyes (jaundice).
- 🔑 Jaundice can be pre-hepatic, hepatic, or post-hepatic, and patient symptoms can help distinguish the cause.
- 🩸 Albumin, the most abundant blood protein, is involved in fluid balance and transport; low levels can indicate liver damage or other conditions.
- ⏱ Prothrombin time (PT) measures blood clotting and can be affected by liver damage, vitamin K deficiency, or anticoagulant medication.
Q & A
What are the main components of a liver function blood test?
-The main components of a liver function test include ALT, AST, ALP, GGT, bilirubin, albumin, and prothrombin time. These components reflect both liver damage and its ability to conjugate and synthesize proteins.
What does it mean when ALT and AST levels are elevated in a liver function test?
-Elevated ALT and AST levels indicate damage to the liver cells or hepatocytes, often due to a disease process affecting the liver.
How can the ratio of ALT to AST help in diagnosing liver conditions?
-An ALT greater than AST is generally associated with liver diseases, while an AST greater than ALT, especially if AST is more than twice ALT, can indicate liver cirrhosis or acute alcoholic hepatitis.
What is the significance of ALP and GGT in liver function tests?
-ALP and GGT are markers for cholestatic damage, indicating a problem with the flow of bile. ALP is also found in bone, so its elevation can also be due to bone damage, while GGT is more specific to bile duct cells.
How can you distinguish between hepatocellular injury and cholestasis using liver function tests?
-By comparing the ratio of ALT to ALP. If ALT is 10 times greater than normal with ALP less than three times greater, it suggests hepatocellular injury. If ALT is less than 10 times normal and ALP is over three times greater, it indicates cholestasis.
What are some common causes of liver damage reflected in liver function tests?
-Common causes of liver damage include alcoholic fatty liver disease, non-alcoholic fatty liver disease, viral hepatitis, drug toxicity, autoimmune hepatitis, and liver cirrhosis.
What role does bilirubin play in liver function, and how can its levels indicate liver problems?
-Bilirubin is a breakdown product of hemoglobin that the liver processes. Elevated bilirubin levels can indicate liver problems, and when it reaches a certain level, it can cause jaundice, which is visible as a yellowing of the skin and eyes.
How can changes in the color of urine and stool help differentiate the causes of jaundice?
-Conjugated jaundice causes darker urine due to water-soluble bilirubin in the urine, while post-hepatic jaundice causes pale stools due to the blockage of bile flow, which normally contains bilirubin.
What is the primary function of albumin in the body, and how can its levels be affected by liver damage?
-Albumin is the most abundant blood protein, responsible for maintaining oncotic pressure and transporting other molecules. Low albumin levels can result from liver damage, as the liver cannot synthesize it as quickly, or from excessive loss through the kidneys or during an inflammatory response.
What does prothrombin time measure, and how can it be related to liver function?
-Prothrombin time measures the time it takes for blood to clot, focusing on the clotting factors in the extrinsic pathway of blood coagulation. It can be high in liver damage, vitamin K deficiency, or due to the effects of medications like warfarin.
How can the information from liver function tests be used to identify different types of liver issues?
-Liver function tests can identify hepatocellular damage, cholestatic damage, and reduced synthetic function of the liver by analyzing the levels and ratios of various components like ALT, AST, ALP, GGT, bilirubin, albumin, and prothrombin time.
Outlines
🧪 Liver Function Blood Tests Overview
This paragraph introduces the video's focus on liver function blood tests, explaining that viewers will learn about the significance of each test component and how to interpret them for diagnosis. It mentions the main components of the liver function test, including ALT, AST, ALP, GGT, bilirubin, albumin, and prothrombin time, which reflect liver damage, bile flow issues, and the liver's synthetic capabilities. The video encourages viewers to like and subscribe for more informative content.
📈 Understanding Liver Function Test Results
The second paragraph delves into the specifics of liver function tests, discussing how elevated levels of ALT and AST indicate hepatocellular damage, while ALP and GGT suggest cholestatic damage due to bile flow issues. It explains the ALT/AST ratio's significance in diagnosing liver diseases and cirrhosis. The paragraph also covers the role of ALP and GGT in identifying the source of damage, whether it's from the liver or bones. It further explains the process of bilirubin production and conjugation, how jaundice occurs, and the distinction between pre-hepatic, hepatic, and post-hepatic causes. Additionally, it touches on albumin's role in blood protein synthesis and oncotic pressure, and the importance of prothrombin time in assessing blood clotting related to liver function. The summary concludes by reiterating the video's educational purpose and encouraging viewers to explore more videos on blood test interpretation.
Mindmap
Keywords
💡Liver Function Blood Tests
💡ALT (Alanine Transaminase)
💡AST (Aspartate Transaminase)
💡ALP (Alkaline Phosphatase)
💡GGT (Gamma-Glutamyl Transpeptidase)
💡Cholestatic Damage
💡Bilirubin
💡Albumin
💡Prothrombin Time (PT)
💡Jaundice
💡Hepatocellular Injury
Highlights
Introduction to liver function blood tests and their role in diagnosis.
Explanation of the main components of liver function tests: ALT, AST, ALP, GGT, bilirubin, albumin, and prothrombin time.
ALT and AST as markers of liver cell or hepatocyte damage due to disease processes.
ALP and GGT as indicators of cholestatic damage related to bile flow issues.
ALT's specificity in liver damage assessment due to its predominance in liver parenchymal cells.
AST's presence in multiple organs and its implications for liver damage diagnosis.
The ALT/AST ratio and its association with liver diseases, including cirrhosis and alcoholic hepatitis.
Non-liver causes of high AST levels, such as myocardial infarction or rhabdomyolysis.
Common causes of liver damage, including alcoholic and non-alcoholic fatty liver diseases, viral hepatitis, and drug toxicity.
ALP's role in indicating damage to bile ducts and bones.
GGT as a specific test for cholestatic damage due to its presence in bile duct cells.
Interpreting combined ALP and GGT levels to identify cholestatic issues.
Differentiating hepatocellular injury from cholestasis by comparing ALT and ALP ratios.
Bilirubin's role in the breakdown of hemoglobin and its processing by the liver.
Causes of jaundice and how bilirubin levels can indicate pre-hepatic, hepatic, or post-hepatic issues.
Albumin's function in maintaining blood oncotic pressure and its synthesis in the liver.
Prothrombin time as a measure of blood clotting and its relation to liver function.
Summary of liver function tests' components and their use in identifying liver damage and synthetic function.
Transcripts
hi everyone in this video we will cover
the liver function blood tests
by the end of it you will understand
what each component of the test means
and how to interpret them to help make a
diagnosis
if you find the video useful please
consider liking the video and
subscribing to my channel
these are the main components of the
liver function test
high alt ast
alp and ggt all reflect some form of
damage to the liver
whilst bidirubin albumin and profrombin
time reflects the liver's ability to
conjugate and synthesize protein
firstly let's look at the markers of
liver damage
alt and ast are often raised when the
liver cells or hepatocytes are being
damaged by a disease process
whereas alp and ggt will be raised when
there is a problem with the flow of bile
which carries bilirubin from the liver
to the small intestines
this is known as cholestatic damage
alt is found predominantly in the liver
parenchymal cells and so is released
into the blood when these cells are
damaged ast is also found in liver
parenchymal cells but additionally it's
present in heart muscle skeletal muscle
kidneys and the brain this makes alt a
more specific test for determining liver
damage
when interpreting alt and ast we can
look at a ratio between them
an alt greater than ast is associated
with most liver disease
but ast greater than aot
can be associated with liver cirrhosis
or acute alcoholic hepatitis
particularly if ast is more than two
times greater than alt
a high ast could also be due to
non-liver causes for example myocardial
infarction or rhabdomyolysis
some common causes of liver damage are
alcoholic fatty liver disease
non-alcoholic fatty liver disease
viral hepatitis
drug
toxicity autoimmune hepatitis
and liver cirrhosis which is the end
process of prolonged damage to the liver
alp and ggt are tests for kodostatic
damage
alp is found in the bile duct and bone
so damage to either of these will cause
alp to be released into the blood
ggt is just found in bile duct cells
making it a more specific test for
cholestatic damage
so if you see a rise in both alp and ggt
you can be fairly confident it's due to
codeostasis
a rise in alp alone is caused by damage
to bone
to help distinguish whether lfts are
showing you her pathocellular injury
versus codiostasis we can compare the
ryzen alt with the ryzen alp
if the alt is 10 times greater than it
should be with alp being less than three
times greater it's probably
hepatocellular injury
if aot is less than 10 times normal
value with the alp over three times
greater than its normal value there's
cody
stasis it's also possible to have a
mixed picture of liver damage and
codeostasis
to finish we're going to look at the
markers of synthetic function
bilirubin is a breakdown product of
hemoglobin so it's released into the
blood when red blood cells hemolyze
this is usually a natural part of the
red blood cell cycle where bilirubin
will travel to the liver
a healthy liver will conjugate bilirubin
which means a molecule is added to it
conjugated bidirubin is water-soluble so
it can be excreted by the kidneys into
the urine
some bilirubin is also excreted via the
bile duct into the feces
bilirubin is raised in some diseases
when it reaches a level of 60 micromoles
per liter in blood the patient will
appear jaundice
causes of jaundice can be divided into
pre-hepatic
hepatic and post-hepatic
pre-hepatic jaundice is due to excess
production of bilirubin i.e pathological
hemolysis
since this process occurs before the
bilirubin has reached the liver it will
be unconjugated
hepatic causes of jaundice are those
that prevent the liver from processing
bilirubin efficiently
post-hepatic jaundice is caused by
anything that blocks the flow of bile
from the liver to the small intestines
we can help distinguish between these
three causes by asking the patient about
changes in color to urine and stool
a conjugated jaundice will cause the
urine to become darker since conjugated
bilirubin is water-soluble and will end
up in the urine
post-hepatic jaundice will also cause
stools to become pale since it blocks
the flow of bilirubin containing bile
into the small intestines where
bilirubin would usually give stool a
darker colour
albumin is the most abundant blood
protein in the body
its main functions are to maintain
oncotic pressure in the blood which
stops fluid leaking out of blood vessels
and is also a transporter protein for
other molecules in the blood
albumin can be low in liver damage as it
can't be synthesized as fast
it could also be caused by excessive
loss of albumin through the kidneys in
nephrotic syndrome
it's also low during an inflammatory
response
finally prothrombin time is a
measurement of how long our blood takes
to clot
more specifically it looks at the
clotting factors in the extrinsic
pathway of blood coagulation i'll cover
this topic in another video
pt can be high if a patient takes
warfarin which means the drug is working
also in vitamin k deficiency
and liver damage
so to summarize we've covered all the
major components of lfts and how they
can be used to identify liver damage
cholestatic damage and reduce synthetic
function of the liver
thanks for watching and feel free to
check out my other videos on
interpreting blood tests see you next
time
Weitere ähnliche Videos ansehen
Hepatic Blood Flow: Clinical Situations
Liver Function Tests - an overview
Liver Architecture Made Simple! Classic Lobule, Hepatic Lobule, Heptaic Acinus
Demystifying Liver Function Tests | Easy Algorithm for Medical Practitioners
Portal Venous Systems, Hepatic Portal System and Liver Functions, Animation
Jaundice - causes, treatment & pathology
5.0 / 5 (0 votes)