Bilirubin is metabolite of heme.Bilirubin has been shown to possess important functions as an anti-oxidant.It very important for the body to be able to excrete bilurubin because is potentially toxic .80% of bilirubin formed in the body come from the release from senesent of the RBC ,the remaining originate from varoius heme -containing protein found in other tissue.
SYNTHESIS OF BILIRUBIN
The Red blood get damage in the spleen and in the liver and release hemoglobin ,hemoglobin split into heme and globin.
Heme is reduce into Biliverdin by enzyme heme oxygenase.Biliverdin is reduce to Bilirubin(unconjugated bilirubin)by ezyme biliverdin reductase.
Uncojugated bilirubin form bind with albumin to make Albumin bilirubin complex.Albumin bind bilirubin in loose combination ,so when present in excess ,bilirubin can easily dissociate from albumin and therefore displace bilirubin from albumin.bilirubin release move to the sinusoidal surface of the liver.
Bilirubin taken to the liver are conjugated which bind with glucuronic acid by the enzyme glucuronyltransferase which make it water soluble and is excreted in the BILE.
HYPERBILIRUBINEMIAS
hyperbilirubinemia describe as an excess of bilirubin in the blood ,excessive destruction of red blood cell.
Conjugated hyperbilirubinemia and unconjugated hyperbilirubinemia.
Conjugated hyperbilirubinemia
*Crigler -Najjar syndrome
*Dubin-johnson
*Rotor's syndrome
Unconjugated hyperbilirubinemia
*Gilbert syndrome.
JAUNDICE
Jaundice is a yellow colouration of conjunctive ,mucous membrane ansd skin due to increased bilorubin level.Jaundice is visible when serum bilirubin exceed 2.5mg/dl
Classification of jaundice
Hemolytic jaundice:is caused as an increased rate of hemolysis.increase breakdown of RBC lead to an increase in amount of unconjugated bilirubin present in the blood and deposition of this unconjugated bilirubin into various tissue can lead to a jaundiced apperance .
Hemolytic jaundice commonly disease of the kidney such as hemolytic uremic syndrome ,can also lead to colourless.
There is increase production of bilirubin leaf to increased production of urine-urobilinogen .
Bilirubin is not usually found in the urine because unconjugated bilirubin is not water soluble so the combination of increased urine-urobilinogen with no bilirubin in urine is calked hemolytic jaundice.
Neonatal jaundice: are usually harmless.this is condition see in infants around the second day after birth lasting untill day 8 in normal birth nd 14days in premature birth.
Serum bilirubin drops to low level without any intervention required.increase where bilirubin rise higher a brain damage condition called kerniterus can occur leading to significant disability.
Blood transfusion or phototherapy is use for treatment
Obstruction jaundice.:blockage in the bile duct.
