HEME CATABOLISM
PREPARED BY MR. ABHIJIT DAS
HEME DEGRADATION PATHWAY:
1.
Heme Breakdown:
Heme, a component of hemoglobin, is broken down by an enzyme called heme
oxygenase.
2.
Biliverdin Formation:
Heme oxygenase converts heme into biliverdin, releasing carbon monoxide and
ferrous iron as byproducts.
3.
Bilirubin Formation:
Biliverdin is then converted into bilirubin by another enzyme called biliverdin
reductase.
4.
Liver Processing:
Bilirubin is conjugated with glucuronic acid to form water-soluble bilirubin
glucuronides.
5.
Excretion:
Bilirubin glucuronides are excreted from the liver into bile and eventually
eliminated from the body through feces.
JAUNDICE:
Jaundice is a condition characterized by yellowing of the skin and eyes due to high levels
of bilirubin in the bloodstream.
Types:
1.
Hemolytic Jaundice
2.
Hepatocellular Jaundice
3.
Obstructive Jaundic
1.
Hemolytic Jaundice:
This type happens when red blood cells are broken
down too quickly. It leads to too much bilirubin being produced, which
the liver can't process fast enough. This often results from conditions like
sickle cell disease or autoimmune disorders.
2.
Hepatocellular Jaundice:
This type occurs when the liver is damaged or not
working properly. The liver can't process bilirubin effectively, causing
it to build up in the bloodstream. It can be due to conditions like hepatitis
or liver cirrhosis.
3.
Obstructive Jaundice:
This type happens when there's a blockage in the
bile ducts, preventing bile (and bilirubin) from reaching the intestines.
This blockage can be caused by gallstones, tumors, or inflammation. When bile
can't flow properly, bilirubin builds up in the blood and causes jaundice.
VAN DEN BERG TEST:
This is a test used to diagnose jaundice. It
involves mixing the patient's serum with a reagent called sulfanilic acid.
Depending on the color change, it can indicate different types of jaundice.
1.
If the serum
turns purple when mixed with sulfanilic acid alone, it suggests obstructive jaundice. This occurs when there's a
blockage in the bile ducts, preventing bilirubin from being excreted properly.
2.
If the serum
turns purple when mixed with sulfanilic acid and methanol,
it suggests hemolytic jaundice. This occurs
when there's an increased breakdown of red blood cells, leading to elevated
bilirubin levels.
These color changes help doctors determine the
underlying cause of jaundice in the patient.