Functions
of Liver
Storing glycogen (fuel for the body) which is made
from sugars.
Helping to process fats and proteins from digested
food.
Making proteins that are essential for blood to clot
(clotting factors)
Processing many medicines which you may take; helping
to remove poisons and toxins from the body
The liver also makes bile. This is a greenish-yellow
fluid which contains bile acids, bile pigments and
waste products such as bilirubin. Liver cells pass
bile into bile ducts inside the liver. The bile flows
down these ducts into larger and larger ducts, eventually
leading to the common bile duct. The gallbladder is
like a 'cul-de-sac' reservoir of bile which comes
off the common bile duct. After you eat, the gallbladder
squeezes bile back into the common bile duct and down
into the duodenum (the first part of the gut after
the stomach). Bile in the gut helps to digest fats.
Liver
Function Tests
As the liver performs
it's various functions it makes a number of chemicals
which pass into the bloodstream and bile. Various
liver disorders alter the blood level of these chemicals.
Some of these chemicals can be measured in a blood
sample. Some tests which are commonly done on a blood
sample are called 'LFTs' (liver function tests). These
tests assess the general state of the liver and biliary
system. LFTs are a group of blood tests that can help
to show how well a person's liver is working.
LFTs |
Acronym |
Normal values |
Utility |
Total Protein |
TP |
60-80 g/L |
The liver produces most of the
plasma proteins in the body. So it makes sense
to measure the amount of protein in the blood.
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Albumin |
Alb |
g/L (38-55) |
A major protein
formed by the liver. It is the main constituent
of total protein; the remaining fraction is
called globulin. It is the major protein that
circulates in the bloodstream. As it is made
by the liver and secreted into the blood it
is a sensitive marker and a valuable guide to
the severity of liver disease. And chronic liver
disease causes a decrease in the amount of albumin
produced. Albumin levels are decreased in chronic
liver disease, such as cirrhosis. It is also
decreased in nephrotic syndrome, where it is
lost through the urine. |
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Alanine transaminase |
ALT |
U/L (5 to 45) |
Also called as Serum Glutamic Pyruvic
Transaminase (SGPT). ALT is an enzyme present
in hepatocytes (liver cells). When a cell is damaged,
it leaks this enzyme into the blood, where it
is measured. ALT rises dramatically in acute liver
damage, such as viral hepatitis.All types of liver
inflammation can cause raised ALT. Liver inflammation
can be caused by fatty infiltration (see fatty
liver) some drugs/medications, alcohol, liver
and bile duct disease. |
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Aspartate aminotransferase |
AST |
U/L (5 to 45) |
Also called as Serum Glutamic Oxaloacetic
Transaminase (SGOT). This is a mitochondrial enzyme
that is also present in heart, muscle, kidney
and brain therefore it is less specific for liver
disease. AST is similar to ALT in that it is another
enzyme associated with liver parenchymal cells.
It is raised in acute liver damage. It is also
present in red cells and cardiac muscle. In many
cases of liver inflammation, the ALT and AST activities
are elevated roughly in a 1:1 ratio. |
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Alkaline Phospahte |
AP |
U/L (30 to 120) |
It is an enzyme in the cells lining
the biliary ducts of the liver. If there is an
obstruction in the bile duct, e.g. gallstones,
ALP levels in plasma will rise. ALP is also present
in bone and placental tissue, so it is higher
in growing children (as their bones are being
remodelled).Conditions such as Primary Biliary
Cirrhosis and Sclerosing Cholangitis will generally
show a raised AP. Raised levels may also occur
in cirrhosis and liver cancer. |
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Total bilirubin |
TBIL |
3 - 18 umol/L (0.174 - 1.04mg/dL) |
Bilirubin is a breakdown product
of heme (a part of hemoglobin in red blood cells),
that results from the destruction of old red blood
cells The liver is responsible for clearing this,
excreting it out through bile into the intestine.
Problems with the liver or blockage of the drainage
of bile will cause increased levels of bilirubin,
as will increased haemolysis of red cells.Bilirubin
concentrations are elevated in the blood either
by increased production, decreased uptake by the
liver, decreased conjugation, decreased secretion
from the liver or blockage of the bile ducts.In
bile duct obstruction, or diseases of the bile
ducts such as primary biliary cirrhosis or sclerosing
cholangitis, the alkaline phosphatase and GGT
activities are often elevated along with the direct
bilirubin concentration.Direct bilirubin, or unconjugated
bilirubin is often measured in tandem, especially
if the total bilirubin level is elevated. Bilirubin
is unconjugated before the liver modifies it for
excretion. It is dangerous in babies, as it can
pass the blood-brain barrier causing kernicterus. |
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Gamma glutamyl transpeptidase |
GGT |
U/L (5 to 35) |
Although reasonably specific to
the liver and a more sensitive marker for cholestatic
damage than ALP, Gamma glutamyl transpeptidase
(GGT) may be elevated with even minor, sub-clinical
levels of liver dysfunction. It can also be helpful
in identifying the cause of an isolated elevation
in ALP. GGT is raised in alcohol toxicity (acute
and chronic). GT is often elevated in those who
usealcohol or other liver toxic substances to
excess. GGT is also induced by many drugs, including
alcohol, therefore often when the AP is normal
a raised GGT can often (but not always) indicate
alcohol use. Raised GGT can often be seen in cases
of fatty liver and also where the patient consumes
large amounts of Aspartame (artificial Sweetener)
in diet drinks for example. |
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Platelet count |
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Platelets are cells that form the
primary mechanism in blood clots. They're also
the smallest of blood cells. They derived from
the bone marrow from the larger cells known as
megakaryocytes. Individuals with liver disease
develop a large spleen. As this process occurs
platelets are trapped with in the sinusoids (small
pathways within the spleen) of the spleen. While
the trapping of platelets is a normal function
for the spleen, in liver disease it becomes exaggerated
because of the enlarged spleen (splenomegaly).
Subsequently, the platelet count may become diminished. |
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Prothrombin time |
Clotting Studies |
Seconds (11 to 13.5) |
The prothrombin time is tested
to evaluate disorders of blood clotting, usually
bleeding. It is a broad screening test for many
types of bleeding disorders. When the liver is
damaged it may fail to produce blood clotting
factors. |
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Lactate Dehydrogenase |
LD |
U/L (100-225) |
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Disease Markers
Disease |
Specific change in proteins in blood |
Wilson's disease |
Ceruloplasmin is reduced |
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An uncommon cause of cirrhosis |
Lack of 1-antitrypsin |
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Haemochromatosis |
A high level of ferritin |
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Hepatocellular injury |
Aspartate Aminotransferase
(AST) and Alanine Aminotransferase (ALT). While
ALT is cytosolic, AST has both cytosolic and mitochondrial
forms. |
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Cholestasis |
AP and gamma-glutamyltransferase
(GGT) levels typically rise to several times the
normal level after several days of bile duct obstruction
or intrahepatic cholestasis. |
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Diffuse infiltrative diseases
of the liver such as infiltrating tumors |
Highest liver AP elevations--often
greater than 1,000 U per L, or more than six times
the normal value |
Disease Tests
or Procedures
Diseases |
Tests or Procedures |
Fatty liver (Non Alcoholic SteatoHepatitis
or NASH) |
Ultrasound Liver Biopsy |
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Hepatitis A |
Antibody Test (Blood Sample) |
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Hepatitis B |
Antibody & AntigenTests Hepatitis
B DNA (Blood Sample) [Liver Biopsy if chronic
to assess level of liver damage] |
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Hepatitis C |
Antibody Test/ Hepatitis C RNA
(Blood Sample) [Liver Biopsy if chronic to assess
level of liver damage] |
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Primary Biliary Cirrhosis |
Biopsy/ Bile duct imaging |
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Primary Sclerosing Cholangitis |
Biopsy/ Bile duct imaging |
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Autoimmune Hepatitis |
Liver Biopsy |
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Wilson’s Disease |
Genetic Analysis/ Copper studies
(Blood and Urine Samples) |
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Alcohol Related Liver Disease |
Liver Biopsy/ Liver Function Tests |
Biopsy
This is a procedure
which involves using a special needle to remove tissue
from the liver to be examined in the laboratory. This
will be used to assess the extent of scarring, fatty
infiltration or liver damage.
For the biopsy,
you will lie on a hospital bed on your back or turned
slightly to the left side, with your right hand above
your head. After marking the outline of your liver
and injecting a local anesthetic to numb the area,
the physician will make a small incision in your right
side near your rib cage, then insert the biopsy needle
and retrieve a sample of liver tissue. In some cases,
the physician may use an ultrasound image of the liver
to help guide the needle to a specific spot.
It is still regarded
as the most accurate way of assessing the status of
the extent of damage to the liver. Firstly a blood
sample will be taken to check your blood’s ability
to clot. This is a routine precaution and is to ensure
the liver biopsy can be performed safely with minimal
risks. A local anaesthetic is administered prior to
the liver biopsy procedure. This may be above the
site of the liver (on your right side of your abdomen
and below your ribs) or more likely between your lower
ribs on your right side. In some cases a light sedative
can be given if you require it, but discuss this with
your doctor.
In some cases the liver biopsy can
be done under ultrasound guidance so the liver can
be seen and the biopsy directed by the imaging. You
may already have had an ultrasound performed prior
to the biopsy; it involves using a probe on your skin
to pass sound waves through the skin - these are bounced
back to provide an image of your internal organs.
This procedure may be uncomfortable.
Liver biopsy is considered a minor
surgery and is done at the hospital. However it should
be noted that this procedure is not without risk –
it is important that it is carried out by a very experienced
Doctor. The risks include puncture of the lung or
gallbladder, infection, bleeding, and pain. The bleeding
in particular is a dangerous complication. It carries
about a 1/10000 death rate.
The different types of Liver Biopsy
are:
Needle biopsy
Usually, liver biopsies
are performed by needle by making a small puncture
in the skin. Patients are given a local anesthetic
to numb the area where the needle will be inserted.
This usually takes less than 10 minutes.
Laparoscopic
biopsy
Sometimes, when
several areas of the liver have to be biopsied or
biopsy is needed from an area which cannot be accessed
using ultrasonic guidance or the lesion very close
to blood vessel is to be biopsied, laparoscopic biopsy
may be performed. A laparoscope is a special tube
that sends images to a monitor and contains surgical
instruments. The tube is inserted through an incision
in the patient's abdomen. The surgeon watches the
monitor and uses the surgical instruments to remove
the tissue samples.
Transjugular
biopsy
In patients with
blood clotting problem or with ascites, normal blind
percutaneous needle biopsy can not be done due to
fear of complications. "Transvenous biopsy"
may be used in such situation. A biopsy is obtained
by putting a biopsy needle through a neck vein.
Who should avoid biopsy?
People
with blood clotting disorders
People
who are on blood thinning medication such as Warfarin,
Coumadins, Ibuprofin, aspirin
People
with hemangiomas (benign liver cyst consisting of
twisted congested blood vessels)
Liver ultrasound
The ultrasound is
a procedure, which may be uncomfortable but can provide
useful information. Ultrasounds are routine tests,
but for a patient it may be a concerning or worrying
time. This information sheet explains the procedure
and aims to answer some questions you may have.
Alongwith the routine
liver function tests and the biopsy, there would be
a need to go for an ultrasound.
Your liver ultrasound will usually be performed in
the X-ray department of the hospital, or in an outpatient’s
clinic, day care department or on a ward. Normally
the ultrasound of your liver is a procedure done by
a doctor who is a radiologist.
The ultrasound should not be painful,
but you may find it uncomfortable and it may take
10 – 15 minutes. If you have any questions about
this ask your doctor when they arrange the appointment
or while you are having the ultrasound.
You will be asked to uncover the
top of the right half of your abdomen, (below your
ribs) and lie on your back. Gel will be applied to
your skin, which may feel slightly cold.
A probe, like a microphone, will
be moved across your skin over your liver. The gel
makes this easier and ensures the soundwaves are carried
through your skin.
While the probe passes over your
liver, soundwaves are directed through your skin and
anything solid will bounce back as a picture via the
probe. A picture based on the reflected soundwaves
will be seen on a screen.
Once the procedure is done and the
probe removed, the gel will be wiped off your skin.
You will then be able to go home or onto an appointment
if one is scheduled. If you are a hospital patient
you will be advised if you are to stay or go home.
The machine will record the images
(pictures) of your liver and a report will be made
by a Radiologist. This report may be ready soon after
your ultrasound, but it may take one to two weeks.
You should have an appointment arranged to discuss
the result with your specialist.
Sometimes the specialist will discuss
the type of picture received from your liver ultrasound
as being “echogenic”. This term means
how well the liver shows up on the ultrasound (something
a bit like being “photogenic”). The report
will tell you and your specialist about the surface
of the liver and the general shape of the liver, as
well as if there are significant changes from the
normal surface and shape. It will only highlight anomalies
or abnormalities, but will not give you a detailed
view of them.
An ultrasound of your liver is similar
to flying over the area you live. You will get a good
view of your house and the surroundings, (bird’s
eye view) and gives a different look at something
you thought you were quite familiar with. However,
it will not necessarily give you as detailed a view
as if you were walking around your house and examining
the ground closely. This may mean a further test called
a liver biopsy may be needed to definitely diagnose
the liver disease.
If you have any concerns discuss
your liver ultrasound with your doctor or nursing
staff and make sure you have the answers you need
to make an informed decision.
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