liver function 3 Flashcards
Jaundice
is a symptom not a disease
describes discoloration of the skin, eyes & mucous membranes most often resulting from the retention of bilirubin
bilirubin levels >42µmol/ L = jaundice
- normal bilirubin: 3-17µmol/L
can result from unconjugated bilirubin, conjugated bilirubin or both forms
increased bilirubin in plasm /serum is called icterus
- the serum/plasma will be a dark yellow/orange color
classification of Jaundice
jaundice is most commonly classified based on the site of the disorder: prehepatic, hepatic & post hepatic jaundice
Prehepatic: occurs when the the problem causing the jaundice occurs prior to liver metabolism
hepatic jaundice occurs when the primary problem causing the jaundice resides in the liver ( intrinsic liver defect or disease)
post-hepatic Jaundice results from biliary obstructive disease, usually from physical obstruction (gallstones or tumors) that prevent the floe of conjugated bilirubin into the bile canaliculi
Prehepatic jaundice
aka hemolytic jaundice
- increase in unconjugated bilirubin
- due to an increase RBC breakdown
- most common cause - Acute or Chronic hemolytic anemia
- liver function is normal & functions at max capacity
- it works harder/faster to conjugate the increased amount of bilirubin entering it
- increased urobilinogen/urobilin in feces
- due to an increased conjugated bilirubin entering intestines
- increased enterohepatic circulation of urobilinogen
- increased amount carried back to liver
- increased urinary urobilinogen
Hepatic jaundice causes
caused by a problem in the liver itself
- intrinsic liver defect or disease
can be caused by :
- bilirubin metabolism defect ( conjugation problem)
- hepatocellular damage
- transport defects ( post- conjugation )
Hepatic jaundice causes ( disorder of bilirubin metabolism)
- disorder of bilirubin metabolism ( conjugation defect)
- increase in conjugated bilirubin :
Gilbert’s syndrome
- mutation in the gene for the enzyme UDPGT
- conjugation systen working at 30 % of normal
- majority dont require treatment
Crigler-Najjar type I
- NO UDPGT enzyme
- fatal-luver transplant needed
Crigler-Najjar type II
- mutation causes severe deficiency of UDPGT enzyme
Neonatal Jaundice
- UDPGT enzyme not fully mature/ developed in the newborn
Neonatal Jaundice or Physiological Jaundice of the newborn
- unconjugated hyperbilirubinemia
50% of newborns are clinically jaundice in the first 5 days after birth
Uridyl diphosphate glucuronyl transferase ( UDPGT) enzyme in liver is immature
- this is the enzyme involved in the conjugation of bilirubin in the liver
Pattern of Neonatal Jaundice
in full term infants:
- no jaundice in the first 24hrs
- peak 3-6 days
- normal in a week
premature babies have a higher peak & greater risk
Neonatal Jaundice is abnormal when
appears in first 24hrs after birth
- may indicate increased RBC breakdown ( a hemolytic process)
> 204µmol/L for full term infants
340µmol/L for premature infants
stays elevated after first week in full term babies
there is an increase in conjugated bilirubin
- this would indicate that it is not an enzyme problem
Clinical significance of infant Hyperbilirubinemia
life threatening
unconjugated billirubin can pass through blood brain barrier
Kernicterus- brain damage caused by bilirubin deposits
infants with high levels of unconjugated bilirubin need phototherapy ( or exchange transfusion)
Hepatic jaundice causes ( hepatocellular damage)
- Hepatocellular Damage
- increase in both foems of bilirubin
- amounts variable based on the cause of damage
- urine bilirubin - POS
unconjugated bilirubin rises when the liver can not properly conjugate the bilirubin for excretion into the intestines
hepatocellular damage slows the excretion of conjugated bilirubin into the intestine, causing it to regurgitate back into the sinusoidal blood general circulation
when serum conjugated bilirubin increaes, it is excreted by the kidneys , goving a positive urine bilirubin
