Liver function tests
( LFTs )
xiaoli
Review: Liver
The
liver is the largest organ in
the body
It is located below the diaphragm
in the right upper quadrant of the
abdominal cavity and extended
approximately from the right 5th
rib to the lower border of the rib
cage.
The
liver is separated into a
right and left lobe, separated
by the falciform ligament. The
right is much larger than the
left .
 The liver performs an astonishingly large
number of tasks that impact all body systems.
 Liver have two channels
that can supply and oxygen
nutriment : hepatic artery
and hepatic portal vein .
The corresponding
channels is hepatic vein
and bile ducts.

The working cells of the liver are known as
hepatocytes, which have a unique capacity to
reproduce in response to liver injury.

Liver regeneration can occur after surgical
removal of a portion of the liver or after injuries that
destroy parts of the liver.

Although the liver's ability to react to damage and
repair itself is remarkable, repetitive insults can
produce liver failure and death.
Functions of liver
①
②
③
Excretory function: bile pigments, bile salts and
cholesterol are excreted in bile into intestine.
Metabolic function: liver actively participates in
carbohydrate, lipid, protein, mineral and vitamin
metabolisms.
Hematological function: liver is also produces
clotting factors like factor V, VII. Fibrinogen
involved in blood coagulation is also synthesized
in liver. It synthesize plasma proteins and
destruction of erythrocytes.
④ Storage functions: glycogen, vitamins A, D and
B12,and trace element iron are stored in liver.
⑤ Protective functions and detoxification:
Ammonia is detoxified to urea. kupffer cells of
liver perform phagocytosis to eliminate foreign
compounds. Liver is responsible for the
metabolism of xenobiotic.
Liver function tests
( LFTs )
What is Purpose of LFTs?






LFTs alone do not give the physician full information, but
used in combination with a careful history, physical
examination (particularly ultrasound and CT Scanning), can
contribute to making an accurate diagnosis of the specific
liver disorder.
Different tests will show abnormalities in response to
liver inflammation
liver injury due to drugs, alcohol, toxins, viruses
Liver malfunction due to blockage of the flow of bile
Liver cancers
 LFTs
are divided into
true tests of liver function,
such as serum albumin, bilirubin, and
protime,
 tests that are indicators of liver injury or
biliary tract disease.

Classification of liver functions test
Classified based on the major functions of liver:
①
Excretion: Measurement of bile pigments, bile salts.
②
Serum enzymes: Transaminase (ALT, AST), alkaline
phosphate(ALP), 5’-nucleotidase, LDH isoenzyme.
③
Synthetic function: Prothrombin time, serum albumin.
④
Metabolic capacity: Galactose tolerance and antipyrine
clearance
⑤
Detoxification :
1. Excretion : Bilirubin

Bilirubin is the main bile pigment that is formed
from the breakdown of heme in red blood cells. The
broken down heme travels to the liver, where it is
secreted into the bile by the liver.
BLOOD
CELLS
Hemoglobin
Stercobilin
excreted in feces
Urobilin
excreted in urine
Globin
Heme
O2
Heme oxygenase
Urobilinogen
formed by bacteria
INTESTINE
reabsorbed
into blood
KIDNEY
CO
Biliverdin IX
via bile duct to intestines
NADPH
Biliverdin
reductase
Bilirubin diglucuronide
(water-soluble)
NADP+
2 UDP-glucuronic acid
Bilirubin
(water-insoluble)
via blood
to the liver
Bilirubin
(water-insoluble)
LIVER
Fig. 2 metabolism of bilirubin
1. serum bilirubin:
Normally,
a small amount of bilirubin circulates in the blood. Serum
bilirubin is considered a true test of liver function, as it reflects the
liver's ability to take up, process, and secrete bilirubin into the bile.
A.
indirect bilirubin
(normal value = 0.3 - 1.2 mg/dl)
B.
direct bilirubin
(normal value ≤ 0.4 mg/dl)
C. total bilirubin
Normal value for = 0.3- 1.2 mg/dl.
VD Bergh reaction
♣ Direct Bilirubin + Diazotized Sulfanilic Acid → Azobilirubin
(Redish purple)
♣ total bilirubin + dimethylsulfoxide(DMSO)+methanol
+diazotized sulfanilic acid to form azobilirubin.
Indirect bilirubin react with diazotized sulfanilic acid after
addition of methanol.
The absorbance of the reaction mixture at 555 nm is directly
proportional to the concentration of direct bilirubin.
OH
COOH
O
O
OH
HO
OH
M
M
V
CH
O
N
H
O
CO
CO
CH2
CH2
CH2
CH2 M
CH2
N
H
N
H
OH
HOOC
O
OH
M V
O
CH
N
H
目录
Difference of two bilirubins
indirect
bilirubin
Binding with Glucuronic acid
Reacting with the diazo
reagent
no
direct
bilirubin
yes
Slow and
indirect
Rapid and
direct
small
large
Discharged via kidney
no
yes
Pass through the
membrane of cell
yes
no
solubility in water
2. urine(/faeces)

A. urobilinogen :
Conjugated bilirubin is excreted via bile salts to intestine.
Bacteria in the intestine break down bilirubin to urobilinogen
for excretion in the feces (normal value for fecal urobilinogen
= 40 - 280 mg/day)
Normally there are mere traces of urobilinogen in the
urine. average is 0.64mg , maximum normal 4mg/24hours.
 B. Urobilin
Urobilin is the final product of oxidation of urobilinogen by
oxygen in air. The amount change with the amount of
urobilinogen excretion .
 B. bilirubinurine:
Bilirubin is not normally present in urine and faese since
bacteria in intestine reduce it to urobilinogen. The kidneys
do not filter unconjugated bilirubin because of its avid
binding to albumin.
conjugated bilirubin can pass through glomerular filter.
Bilirubin is found in the urine in obstructive jaundice due
to various causes and in cholestasis.
Note:
Bilirubin in the urine may be detected even before clinical
jaundice is noted.
Who is a candidate for the test?
Bilirubin is used to diagnosis of jaundice.
Abnormal bilirubin levels can be found in many
disorders, including: blocked bile ducts, cirrhosis,
hepatitis and other liver diseases or immature liver
development in newborns.
Hemolytic Jaundice
Hepatic Jaundice
Obstructive jaundice ( Cholestasis)
Congenital Jaundice
Sample
Indices
Normal
Hemolytic
Jaundice
Hepatic
Jaundice
Obstructive
Jaundice
Serum
Total Bil
＜1mg/dl
＞1mg/dl
＞1mg/dl
＞1mg/dl
Direct Bil
0～0.8mg/dl
↑
↑↑
Indirect Bil
＜1mg/dl
↑↑
Color
normal
deeper
deep
deep
Bilirubin
—
—
＋＋
＋＋
Urobilinogen
A little
↑
uncertain
↓
Urobilin
A little
↑
uncertain
↓
Color
normal
deeper
lighter or
normal
Argilous
(complete
obstruction)
Urine
Stool
2. Serum enzymes
A large number of enzyme estimations are
available which are used to ascertain liver
function. They are be divided into two groups:
I: most commonly and routinely done in the
laboratory.
serum transaminase(ALT/AST)
serum alkaline phosphate(ALP)
II: not routinely done in the laboratory.
Alanine transaminase (ALT)
GPT
ALT or sGPT (serum
glutamate pyruvate transaminase)
Aspartate aminotransferase (AST)
GOT
AST or sGOT (serum
transaminase)
glutamate oxaloacetate
organ
GOT
GPT
organ
GOT
GPT
heart
156000
7100
pancrease 28000
2000
liver
142000
44000
spleen
14000
1200
skeletal 99000
4800
lung
10000
700
kidney
19000
20
16
91000
serum
GPT:
Normal range: 2-59 U/L
GOT:
Normal range: 10-34 U/L
‼ Therefore, when the liver is injured, GPT is
released into the bloodstream.
Elevated levels of GPT may indicate :
 alcoholic liver disease
 cancer of the liver
 cholestasis or congestion of the bile ducts
 cirrhosis or scarring of the liver with loss of function
 death of liver tissue
 Hepatitis or inflammation of the liver
 noncancerous tumor of the liver
 use of medicines or drugs toxic to the liver

GOT also reflects damage to the hepatic
cells and is less specific for liver disease. It can
also be released with heart, muscle and brain
disorders.

Therefore, this test may be ordered to help
diagnose various heart, muscle or brain disorders,
such as a myocardial infarct (heart attack).





Elevated levels of GOT may indicate :
acute hemolytic anemia,
acute pancreatitis or inflammation of the pancreas.
acute renal failure or loss of kidney function.
cirrhosis of the liver.
Hepatitis
 heart attack
 primary muscle disease
 recent surgery
 severe burns
 muscle injury

Although GOT is not a specific for liver as the GPT,
ratios between GPT and GOT are useful to physicians in
assessing the etiology of liver enzyme abnormalities.
◆ normally: GPT is normal, GOT is normal, GPT/GOT is
about 1.15.
◆ Virus hepatitis: GPT↑, GOT is normal ,GPT/GOT＞
1,even more than 2.5；
◆ chronic hepatitis : GPT↑ ,GOT ↑GPT/GOT is about 1.
◆ Liver cancer, cirrhosis, Alcohol-induced hepatitis:
GPT↑ ,GOT ↑ < 1, about 0.6~0.7.
◆ Accute myocardial infarct :< 1
GPT and GOT is in the different distribution of the hepatocytes.
GPT exists primarily in the cytoplasm of liver cell. if there is a slight
liver cell damage, GPT firstly leak into the bloodstream, so that the
serum GPT increased.
The GOT mainly in the "mitochondria“of liver cells, the
mitochondria are "bubble" in the liver cell cytoplasm. if there is a
slight liver cell damage, GOT don`t leak into the bloodstream.
When the GOT was
significantly higher,
mitochondria of liver
cells are injuries.
Alkaline phosphatase (ALP)
 ALP occurs in all tissues, especially liver and
bone.
The alkaline phosphatase test is often used to
help diagnose certain liver diseases and bone
disorders .
 Normal range: 30 - 95 IU/L (3-13 kings unit)
Alkaline phosphatase (ALP or AKP)

ALP is a hydrolase enzyme responsible for removing
phosphate groups from many types of molecules,
including nucleotides and proteins.
– most effective in an alkaline environment
– in humans, alkaline phosphatase is present in all tissues throughout the
entire body, but is particularly concentrated in liver, bile duct, kidney, bone,
and the placenta.

Levels are significantly higher in children and pregnant
women.
Higher levels of ALP than normal may indicate:
 liver disease
 bone disease
 leukemia, a cancer of the blood and bone marrow
 various hormone problems
 pregnancy
Lower levels of ALP than normal may indicate:
 anemia, or a low red blood cell count
 malnutrition
 various hormone problems
Mechanism of increase in ALP in liver
disease:
Increase in the activity of ALP in liver disease is
not due to hepatic cell disruption , nor to a failure of
clearance , but rather to increased synthesis of hepatic
ALP .
The stimulus for this increased synthesis in patients
with liver disease has been attributed to bile duct
obstruction by stone ,tumors , intrahepatically by
infiltrative disorders or space-occupying lesions.
It is used for many years in differential diagnosis
of jaundice. it is increased in both infectious hepatitis
(viral hepatitis) and posthepatic jaundice, but the rise
is usually much greater in case of obstructive
jaundice .
dividing line which has been suggested is 35KA
units/ml. a value higher than 35KA units/ml is
strongly suggestive of diagnosis of obstructive
jaundice, in which very high figures even up to
200KA units/ml or more may be found.
Serum ALP is found to be normal in haemolytic jaundice.
Other enzyme (not done routinely)
5’-Nucleotidase
This enzyme is released by the liver when
the liver is injured due to bile duct obstruction or
impaired bile flow.
Normal range: 2-15 IU/L
LDH isoenzymes
lactate dehydrogenase
 This test measures the total level of the enzyme
lactic dehydrogenase, also called LDH, in the blood.
LDH is found in body tissues and organs.
H H
H H
H H
H M
LDH1
(H4)
LDH2
(H3M)
H H
M M
LDH3
(H2M2)
H M
M M
LDH4
(HM3)
M M
M M
LDH5
(M4)
LDH isoenzymes
۩ Tissue or organ injury can release LDH into the
bloodstream, thereby raising the level. So it is
usually done to see if tissue or organ damage has
occurred.
۩ If he or she suspects a heart attack or liver tissue
damage in the body.
Normal range: 115-225 IU/L
3. Metabolic capacity:
Tests based on livers function:
carbohydrate metabolism
lipid metabolism
protein metabolism
Tests based on livers part in carbohydrate
metabolism
1. Glucose tolerance test
＆ Not of much value in liver diseases
＆ It is often difficult to separate the part
played by the liver from other factors
influencing glucose metabolism.
2. Galactose tolerance test
Basis:
For galactose is a monosaccharide, almost exclusively
metabolized by the liver. the normal liver is able to
convert galactose into glucose; but this function is
impaired in intrahepatic disease and the amount of blood
galactose and urine galactose is excessive.
The liver can be assessed by measuring the utilization
of galactose. This is referred to galactose tolerance test.
◆It is used primarily to detect liver cell injury.
◆ It can be performed in presence of jaundice.
◆ As it measured an intrinsic hepatic function, it may be
used to distinguish obstruction and non obstruction
jaundice.
Method :
oral galactose tolerance test
IV galactose tolerance test(intravenous injection )
oral galactose tolerance test
The test is performed in the morning after a night’s
fast. a fasting blood sample is collected which serves as
“control”.40mg galactose dissolved in a cup-full of water
is given orally.further blood samples are collected at ½
hourly intervals for two hours.
Result:
Normally or obstructive jaundice:
3gm or less of galactose are excreted in the urine
within 3 to 5 hours and the blood galactose returns to
normal within one hour.
Intrahepatic jaundice:
The excretion amounts to 4 to 5gm or more
during the first 5 hours.
3. Fructose tolerance test
Normal response:
shows little or no rise in the blood sugar level. The
highest blood sugar value reached during the test should
not exceed the fasting level by more than 30 mg%.
obstructive jaundice cases:
mresult is obtained in most cases of obstructive jaundice
cases.
In infectious hepatitis or parenchymatous liver cells damage:
rise in blood sugar is greater than above, but the
increases obtained are never very great.
Tests based on livers part in lipids metabolism
Cholesterol-cholesteryl ester ratio:
The liver plays an active and important role in the
metabolism of cholesterol including its
synthesis,esterification,oxidation and excretion.
Normal total blood cholesterol ranges from 150 ~
250mg/dl and approx 60 to 70% of this is in erterified form.
In parenchymatous liver disease:
theer is either no rise or even decrease in total
cholesterol and the ester fraction is always definitely reduced.
the degree of reduction roughly parallels the degree of liver
damage.
In severe acute hepatic necrosis:
the total serum cholesterol is usually low and may fall
below 100mg/dl, whilst there is marked reduction in the %
present as esters.
Tests based on livers part in amino acid metabolism
Determination of blood NH3:
Nitrogen part of amino acid is converted to NH3 in
the liver mainly by transamination and deamination
and it is converted to urea in liver only .
Normal range :
blood ammonia varies from 40μg ammonia nitrogen
per100ml of blood.
In parenchymatous liver disease:
Increases in NH3 can be found more advanced cases of
cirrhosis liver,particular when there areassociated neurological
complicate.in such cases blood levels may be over 200 μ g/ml.
4. Synthetic functions:
1. total plasma proteins/ albumin/ globulin/
A:G ratio
2. Formation of prothrombin by liver
1. Determination of total plasma proteins/ albumin/
globulin/ A:G ratio
This yields most useful information in chronic
liver disease.Liver is the site of albumin synthesis
and also possibly of some of α and β globulins.
Normal value:
total plasma proteins: 80~110mg/dl
albumin:40-50mg/dl
globulin:25~35mg/dl
A:G ratio: 1.5~2.5
In infectious hepatitis:
quantitative estimations of albumin and globulin
may give normal results in the early stages.qualititative
changes may be present,in early stage rise in β globulins and in later stages γ-globulins shows rise.
In cirrhosis liver or parenchymal liver disease:
The albumin is grossly dicreased and the globulins
are often increased,so that A:G ratio is reversed, is
characteristically seen in cirrhosis liver.
Serum Albumin
Albumin is an important blood protein that is
made only by the liver and excreted by the kidneys.
★ Albumin is essential for maintaining the
osmotic pressure in the vascular system. low
albumin level produce ascites.
★ Albumin is also very important in the
transportation of many substances such as drugs,
lipids, hormones and toxins that are bound to
albumin in the bloodstream.
Ascites : the abnormal
accumulation of fluid within the
abdominal and pelvic cavity
(A) Patient with alcoholic cirrhosis who
shows ascites, an umbilical hernia,
and wasting of muscle.
(B) After 2 years of abstinence and
appropriate nutrition, the patient
gained back muscle mass and his
ascites improved.
This test is normally performed to assist in diagnosing
diseases that affect proteins in the body, such as cancer, liver
disease, renal or intestinal problems, and immune disorders.
 Normal range: 34 - 54 g/L
Abnormally low contents of albumin may indicate:
 ascites
 extensive burns
 kidney disease
 liver disease
 malabsorption syndromes
Formation of prothrombin by liver
At least 12 different proteins are involved in clotting.
Blood clotting factors are proteins made by the liver and are
associated with the incorporation of vitamin K metabolites
into a protein. When the liver is significantly injured, these
proteins are not normally produced.
PT (Prothrombin time)
Estimation of plasma fibrinogen
APTT(activated partial thromboplastin time)
Prothrombin time (protime or PT)
★ Prothrombin
is a plasma protein that is converted into
thrombin during blood clotting.
★ Prothrombin
is formed in the liver from inactive
“preprothrombin” in presence of vitamin K.
in presence of vitamin K
thrombin
prothrombin
Ca2+, PL
What is prothrombin time?
prothrombin time is measured as prothrombin
activity. The term prothrombin time was given to time
required for clotting to take place in plasma to III factor and
Ca+ have been added.
★ PT
is used to assess the activity of extrinsic blood
clotting pathway .
★ PT
is also a useful test of liver function, since there is
a good correlation between abnormalities in
coagulation measured by PT and the degree of liver
dysfunction. PT is usually expressed in seconds and
compared to a normal control patient’s blood.
This test may be done:

when a person has a bleeding problem
 to monitor a person who is taking blood-thinning medicine
 before surgery to make sure a person will not bleed too
much during the operation.
 It generally falls 10 - 15 seconds.
Prothrombin activity is also sometimes expressed as
“prothrombin index”, which is the ratio of prothrombin
time of the normal control to the patient’sprothrombin time:
PT of normal control
prothrombin index =
x100
PT OF patient
High PT values may occur when a person:
 is
taking blood-thinning medicines like warfarin
 is taking other medicines, such as certain antibiotics,
that interfere with the test
 has severe liver disease
 has DIC-disseminated intravascular clotting, a
complex blood disorder that occurs when clotting
mechanisms are activated throughout the body
 has certain rare, inherited bleeding disorders
 has a vitamin K deficiency
Abnormally low PT values are usually not
significant. However, they may occur when
a person:
 has cancer
 has blood clots
 is taking certain medicines, such as birth
control pills
Some other tests for LFTs
 Alpha-fetoprotein Test: This protein is produced by the fetal
liver and testes indicating hepatitis or cancer.
 Mitochondrial Antibodies Test: The presence of these
antibodies can indicate primary biliary cirrhosis, chronic active
hepatitis, and certain other autoimmune disorders.
 Platelet count: Platelets are the smallest of all blood cells and
are involved in promoting clotting of the blood, normally a process
of healing. In cases of chronic liver disease where cirrhosis exists,
the platelet count can be lowered — although this can occur due
to many conditions other than liver disease.
 Total protein: measures albumin and all other proteins in
blood, including antibodies made to help fight off infections
Protective functions and detoxification: