Liver Flashcards
What is jaundice?
Yellow discolouration of skin and whites of eyes caused by build up of bilirubin in blood
What is bilirubin?
What’s the difference between conjugated and unconjugated?
The breakdown product of haemoglobin
Haemoglobin is broken down into unconjugated bilirubin.
This is then bound to albumin and then transported to the liver
Here it’s conjugated by an enzyme to become conjugated bilirubin
Then it goes to the gall bladder for storage
Can bilirubin pass blood brain barrier? Unconjugated or conjugated? Why/why not?
Yes, unconjugated bilirubin can because its fat soluble
What is kernicterus?
Pathophysiology
Presentation
Prognosis
When there is excess unconjugated bilirubin in the blood
It crosses blood-brain barrier and is deposited in the basal ganglia or brainstem nuclei
This can lead to lethargy, poor feeding, increased muscle tone, seizures, coma
If they survive, often left with learning difficulties, deafness, chroeathetoid cerebral palsy (chorea and athetoid movements)
You see a 3 day old baby in A+E and he is visibly jaundiced. He is lying with an arched back and mum reports he had a seizure on the way to hospital.
What are you worried about?
Kernicterus
Deposition of unconjugated bilirubin in the brainstem nuceli or basal ganglia
What’s the differential of jaundice occurring within 24 hrs of birth?
Rhesus incompatibility ABO incompatibility G6PD deficiency Spherocytosis Sepsis
Explain why rhesus incompatibility causes jaundice.
If the mother is rhesus -ve has a baby that’s rhesus +ve, the mother creates antibodies against the Rh+ RBCs.
If her next pregnancy is with Rh+ve baby too, mother’s anti-Rh+ antibodies will attack baby’s Rh+ve RBCs
Breakdown of RBC ad haemoglobin = hyperbilirubinaemia = jaundice
Explain why ABO incompatibility causes jaundice? Why is it not very common?
Anti-A and anti-B antibodies are usually IgM, so can’t cross the placenta.
In some women they are IgG so can cross the placenta
If mother has either anti-A or anti-B but baby has A or B antigens on their RBCs then mother’s antibodies will attack baby’s RBCs
Which type of antibodies are:
- anti-A and B
- able to cross placenta?
Anti-A and B = IgM
Cross placenta = IgG
What antibodies do people of these blood groups have?
- A
- B
- AB
- O
A: anti-B
B: anti-A
AB: none
O: both
What is G6PD deficiency?
Which populations is it common in?
Deficiency of the G6PD enzyme which means RBCs don’t function properly (and break down?)
Middle and far east
Afro-caribbean
What is spherocytosis?
When RBCs are spherical instead of bi-concave
They break down more easily
What’s the differential diagnosis of jaundice presenting from 24 hrs to 2 weeks of age?
Physiological jaundice Dehydration Infection Rhesus incompatibility ABO incompatibility G6PD deficiency
What are causes of physiological jaundice?
The breakdown of left over foetal haemoglobin leading to excess bilirubin
Hepatic immaturity, reduced bilirubin conjugation
Exclusively breast feeding: difficulty establishing so dehydrated
What’s the differential of jaundice in a child over 2 weeks old?
Unconjugated bilirubin:
- same causes as in before 2 weeks
- hypothyroidism
- GI obstruction
Conjugated:
- bile duct obstruction
- neonatal hepatitis
