Differential diagnosis of Jaundice:
1. Prehepatic jaundice:
This is caused by hemolytic conditions (sickle
cell disease, shperocytosis, autoimmune). There is increased in unconjugated
bilirubin, bound to albumin and thus absent in urine, hence the term ‘acholuric
jaundice’. Since conjugation is normal, the level of urobilinogen in urine and
faeces increases, because more bilirubin is conjugated. The Hb level is
subnormal. Liver enzymes will be normal. Absence of urinary bilirubin. Presence
of urinary and faecal urobilinogen and unconjugated hyperbilirubinemia. Presence
of bilirubin in urine indicates presence of hepatic or biliary tract disease.
It precedes hyperbilirubinaemia so provides early indication of liver damage.
2. Hepatic (hepatocellular) jaundice:
This occurs due to primary damage to
hepatocytes. There is both conjugated and unconjugated hyperbilirubinemia.
Urinary level of bilirubin increases. Liver enzymes are abnormal. ALP increases
along with γ-GT. ALT is elevated along with AST.
3. Post hepatic (cholestatic or
obstructive, regurgitation) jaundice
There is failure of biliary secretion. This
failure may be at the level of hepatocytes, obstruction occurring anywhere
between biliary canaliculi and the gut. There is conjugated hyperbilirubinemia.
ALP and 5’-NT are elevated. There is lower AST/ALT ratio. Absence of urinary
urobilin and faecal stercobilin thus stool is clay colored. Due to
regurgitation bile salts appear in urine.
4. The inherited hyperbilirubinaemias:
a. Unconjugated
hyperbilirubinemia (Of the total bilirubin increased if increase in
conjugated bilirubin is <20% this is
called unconjugated hyperbilirubinemia).
The crigler-najjar syndrome:
There is complete absence of (type 1)
or reduction (type 2) or UDP-glucuronyl transferase activity and is inherited
as autosomal recessive trait. Due to failure of conjugation there is
unconjugated hyperbilirubinemia in type 1. In type 2 both fraction are
increased but higher is unconjugated. This bilirubin can cross BBB causing
kernicterus. In type 1 there is high mortality but in type 2, survival is
prolonged by giving phenobarbital (which induces enzyme synthesis) along with
phototherapy.
Gilbert’s syndrome:
It is common and characterized by recurrent
mild jaundice, plasma bilirubin level being <100 µmol/L and only abnormality
is standard liver test. There is increase in total bilirubin and the major
fraction is unconjugated bilirubin. This syndrome is due to reduction in
concentration of isoform (UGT-1A) of UDP-glucuronyl transferase.
b. Isolated Conjugated hyperbilirubinemia:
Dubin-Johnson syndrome:
This is inherited as autosomal
recessive manner and characterized by decreased biliary canalicular transport
of conjugated bilirubin due to mutation in transport protein. Another
characteristic defect here is the most of the urinary coproporphyrin is type I,
whereas in unaffected subjects it is mainly type II.
Rotor’s syndrome: This is also an autosomal recessive
characterized by moderate jaundice; there is mild elevation in conjugated
bilirubin. The cause is unknown.
5. Neonatal jaundice
This is called physiological jaundice and
bilirubin seldom exceeds 100 µmol/L and is predominantly unconjugated, due to
increased hemolysis, decreased hepatic uptake and conjugation. This
unconjugated fat soluble bilirubin can cross the BBB and cause brain damage
(Kernicterus). Prophylaxis is by phototherapy at 450 nm when bilirubin is very
high >300 µmol/L.
Role of LFT
in Assessing Prognosis:
Chronic liver disease:
Child-Turcotte-pugh (CTP) classification of
severity of liver disease is,
Biochemical finding 1 2 3
Ascitis Absent Slight Moderate
Encephalopathy (grade) none 1
and 2 3 and 4
Bilirubin (µmol/L) <25 25-40 >40
Albumin (g/L) >35 28-35 <28
PT 1-4 4-6 >6
(Seconds prolonged)
Mild (grade A) –scoring of 5 or 6 points
Moderate (Grade B) – 7-9 points
Severe (Grade C) – 10-15 points
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