Description
In this collection we will learn about the liver and its function test and Some examples of Liver dysfunction
This will be useful for all medical students
Study Set Content:
Liver
– Functions, Disorders
and Diagnostic Tests
Objectives
SLO BI 6.13.1 Enumerate functions of liver
SLO BI 6.14.1 Discuss the biochemical tests
which are done to assess the function of
liver
SLO BI 11.17.5 Enumerate and explain the
biochemical basis of Liver Function tests
SLO BI 6.15.1 Discuss the biochemical
alterations in patients with jaundice
Largest solid organ, right upper quadrant
Large reserve capacity
Capable of regeneration
Functions:
Metabolism:
Fat,
carbohydrates,
protein,
xenobiotics, hormones
Synthesis:
Albumin,
α
and
β
globulins,
coagulation factors
Storage: fluids, vitamins, minerals
Liver
Some examples of Liver dysfunction
Hepatocellular diseases (viral hepatitis, ALD)
Cholestastic disease (intra and extra hepatic
obstruction)
Cirrhosis
Cancer (secondary or primary)
Fatty Liver
Genetic Disorders
Hemochromatosis (iron storage)
Wilsons disease
Liver dysfunction diagnosis
The diagnosis of liver disease depends on
a combination of patient history, physical
examination
,
laboratory testing
, biopsy
and imaging studies such as ultrasound/
CT /MRI scans
Liver Function Test
Used to ……
detect the presence of liver disease
distinguish among different types of liver
disorders
gauge the extent of known liver damage
follow the response to treatment
Liver Function Test
Shortcomings
can be normal in a patient with serious
liver disease and abnormal in a patient
with diseases that do not affect the liver
rarely suggest a specific diagnosis rather
suggest a general category of liver disease
→ further directs the evaluation
Liver Function Test
point to be noted…….
Liver – thousands of biochemical functions –
most cannot be measured
Enzymes – do not measure liver function at all –
detect damage or interference with the bile flow
Interpretation must be performed within the
context of the patient’s risk factors, symptoms,
concomitant
conditions,
medications,
and
physical findings
Differing
laboratories
Differing
normal
values
Liver Function Test
point to be noted…….
No one test enables the clinician to accurately assess
the
liver’s total functional capacity
to increase the sensitivity and specificity
use them as
a battery
when
one
test
provide
abnormal
finding
or
persistently
abnormal
on
serial
determination
–
probability of liver disease is high
when all results are normal
– probability of missing
occult liver disease is low
Commonly
employed
tests:
Bilirubin,
Aminotransferases,
Alkaline phasphatase,
Albimin
and Prothrombin time
Liver Function Test
Sample collection
Serum or plasma
Avoid hemolytic and lipemic sample
Sample transport/storage
Precautions (viral hepatitis B and C)
Liver Function Test
Categorization
Test based on detoxification and excretory
function
Test for enzymes that reflect damage to
hepatocytes
Test for enzymes that reflect cholestasis
Test that measure synthetic function
Liver Function Test
Test based on detoxification and excretory
function:
Van den Bergh assay:
determination of
total, conjugated (direct) and unconjugated
bilirubin (indirect)
Normal value of total < 1-1.5mg/dl
Normal value of direct: up to 15% of the
total (upper limit = 0.3mg/dl)
Liver Function Test
Test
based
on
detoxification
and
excretory function:
Isolated elevation of UCB – bilirubin elevated
but < 15% direct - W/U for hemolysis – if
absent – Gilbert disease
Conjugated hyperbilirubinemia – liver or
biliary tract disease
In most liver diseases both fractions are
increased
Liver Function Test
Test based on detoxification and excretory
function:
Urine Bilirubin:
any bilirubin found in urine is conjugated
bilirubin
bilirubinuria implies the presence of liver disease
Blood ammonia:
Was used for detecting encephalopathy or for
monitoring
hepatic
synthetic
function
(poor
corelation)
Liver Function Test
Test for enzymes that reflect damage to
hepatocytes
Aminnotransferases (ALT and AST):
AST
:
Liver, cardiac muscle, skeletal muscle, kidneys,
brain, pancreas, lungs, leucocytes, and RBC - (Normal
serum level)
ALT
: Liver - (Normal serum level)
Liver cell damage – increased permeability – increase
serum levels
BUT poor correlation b/w liver cell damage and level of
AST and ALT
Up to 300 U/L – non specific/ any type of liver disorder
Liver Function Test
Test for enzymes that reflect damage to
hepatocytes
Aminnotransferases (ALT and AST):
Levels > 1000 U/L extensive hepatocellular injury (viral
hepatitis, Ischemic Liver disease, Drug or Toxin induced)
In most acute hepatocellular damage ALT > AST
AST:ALT > 2:1 (suggestive) & > 3:1 (highly suggestive)
of (Alcoholic Liver Disease) ALD
Aminotransferases are usually not greatly elevated in
obstructive jaundice
Liver Function Test
Test for enzymes that reflect cholestasis:
ALP, 5’NT, GGT
GGT – more diffuse localization – less specific
than ALP and 5’NT
Use of GGT to identify patient with occult
alcohol use – questionable
ALP: non pathological causes of increased levels
Normal levels
Liver Function Test
Test for enzymes that reflect cholestasis:
ALP:
< 3 fold increase: not specific for cholestasis (seen
in almost any type of liver disease)
>4 fold increase: cholestatic liver disorder,
infilterative liver disease (Cancer), bone conditions
with rapid turnover of bone (Pagets disease)
ALP is NOT useful to distinguish b/w intra and
extra hepatic obstruction
Liver Function Test
Test that measure biosynthetic function of
the Liver
Serum albumin:
Synthesized exclusively by hepatocytes
T1/2: 15-20 days
NOT a good indicator of acute/mild hepatic
dysfunction
Minimum change in Viral hepatitis/drug induced
hepatitis/ Obs. Jaundice
In hepatitis Alb levels less than 3gm/dl – chronic
liver disease
Liver Function Test
Test that measure biosynthetic function of
the Liver
Serum albumin:
Other causes of decrease: Protein malnutrition/
Protein
losing
enteropathies
/
Nephrotic
syndrome/ Chronic infections
