Jaundice Flashcards
What is jaundice?
It is the clinical sign of yellow discoloration of the sclera and the skin
When is clinical jaundice evident on babies skin?
-at 75 mmol/l
What is haemoglobin broken down into?
- haem
- globin by the reticulendothelial system (spleen)
What is the globin and haem broken up into?
Haem: biliverdin-then bilirubin
Globin: metabolized into amino acids
What is the bilirubin conjugated by in the liver?
-it is conjugated by glucocronic acid by the enzyme glucoronyl transferase
Is jaundice more common in formula fed or breast fed babies?
Breast fed
What is physiological jaundice?
- jaundice that occurs in more than half normal newborn babies.
- this is because they have increased amounts of unconjugated bilirubin
- this presents on day 2-3 and disappears within 7 days
What is physiological jaundice caused by?
-high haematocrit
-shorter red blood cell survival time which leads to high bilirubin production
Slow hepatic conjugation
-the enterohepatic circulation of bilirubin
How long can we expect babies to have clinical jaundice?
-2 weeks because of their immature liver
Which type of bilirubin crosses the BBB and is dangerous?
Free unconjugated bilirubin(not bound to albumin)
What parts of the brain are most susceptible?
- brain stem
- basal ganglia
- mid-brain
What is the clinical presentation of bilirubin encephalopathy?
- Severe jaundice (visible on hands and feet)
- Lethargy + poor feeding
- High pitched cry
- Setting sun appearance
- Death
How do we classify jaundice?
- Physiological-mild, transient in clinically well infants, does not require phototherapy
- Pathological
When should we suspect pathological jaundice?
- jaundice that presents in the first 24 hours of life
- jaundice that has been there for more than 14 days in a term infant and 21 days in a preterm baby
- jaundice that is too high above the phototherapy line
- conjugated jaundice
What are the causes of pathological jaundice?
- unconjugated jaundice
- Rh and ABO incompatibility
- infection, sepsis - Conjugated jaundice
- obstruction: choledochal cyst biliary atresia
- total parenteral nutrition
- cystic fibrosis
How do we test for jaundice?
- billicheck
- blood gas
What are the special investigations we do in these patients?
- Coombs test
- crp
- blood group test
- haemoglobin
What is the treatment for jaundice?
-phototherapy or exchange blood transfusion
What is the treatment for conjugated bilirubin?
-we need to address the underlying condition(biliary atresia, penicillin for syphillis for example)
What is the frequency of visible light used in phototherapy?
- 420 to 460 nm
Which is the blue end of the spectrums
How does phototherapy work?
The unconjugated bilirubin is isomerised to a water soluble non toxic isomer known as lumirubin which is excreted in the urine and stools
How must we monitor whether phototherapy is working or not?
We can check the total serum bilirubin or the blood gas and check it daily
When can we stop phototherapy?
When the bilirubin is more than 50 mmol/l below the phototherapy line
What is exchange blood transfusion?
It is when the babies blood is removed and is replaced with adult stable plasma
It is done for babies that are at high risk for encephalopathy
We do the transfusion through the umbilical vein or the arterial line
What are the specific causes of neonatal jaundice?
- Rh and ABO incompatibility
- Infection
- Breast feeding jaundice
- Prolonged jaundice
- Late onset jaundice
How does jaundice occur from ABO incompatibility?
The mother is usually group O and the baby is either group A or B
Then when what happens is that the mother has igG antibodies and is able to cross the placenta and cause haemolysis
What is the total serum bilirubin usually at after 6 hours in ABO incompatibility patient’s?
Above 80 mol/l
What tests can we do to confirm this?
- Coombs test
2. Peripheral smear test which will show reticulocytes and spherocytes
How does Rh incompatibility occur?
Mom is Rh negative and dad is always Rh positive
-if baby is Rh positive then those red cells may cross the placenta and cause the mom to form antibodies
What is hydrops fetalis?
Severe anaemia which causes heart failure
Gross oedema and ascites
What can a Rh negative mom be given to prevent the incompatibility?
They can be given anti-D immunoglobulin by intramuscular injection within 72hours of delivery
Polygam
How does breast feeding jaundice occur?
Usually a young mom that struggles with breast feeding or baby unable to latch
What is a possible cause of late onset jaundice?
This is usually after 14 days in term babies or 21 days in preterm babies
It can be caused by an obstruction like biliary atresia
When does the peak of total serum bilirubin occur in term babies for physiological jaundice?
Day 3
When does the peak occur for total serum bilirubin in preterm babies?
-At 5-7 days after birth
In pathological jaundice, by how much does the total serum bilirubin increase every 6 hours?
-50 micromol/l
What are the other clinical signs we can look for in an infant with pathological jaundice?
- Haemolysis
- Hepatosplenomegaly
- light stools, dark urine
What are the red flags of neonatal (pathological jaundice)?
- Jaundice that starts <24 hours of birth
- Jaundice that starts >14 days in term babies and >21 days in preterm babies
- Anaemia
- Rh negative mother
- Positive Coombs test
- Blood group O mom
- Hypothermia, metabolic acidosis, hypoglycaemic, sepsis
- Dark urine, pale stools
- TSB increasing by 50 micromol/l every 6 hours
- > 34 micromol/l or >20% of total serum bilirubin
- Exclusive breastfeed
- Baby is Coombs positive
- Preterm
What are the risk factors for bilirubin encephalopathy?
- hypothermnia
- hypoxaemia
- hypoglycaemia
- metabolic acidosis acidosis
- sepsis
What are the signs that haemolysis is occurring?
- low haematiocrit
- increased reticulocytes
- spherocytosis on the peripheral blood smear
When would we do a billicheck on a baby with a blood group O mom?
-6 hours after birth
What is successful phototherapy?
-when the total serum bilirubin decreases by 17-34 micromol/l within 4-6 hours
What are the side effects of using phototherapy?
- Hypothermia/hyperthermia
- Dehydration
- Skin rashes
- Loose stools
- Bronze baby syndrome
- Potential retinal changes
What are the causes of unconjugated hyperbilibinaemia?
- Increased RBC lysis
- Decreased hepatic uptake
- Increased enterohepatic reabsorption
What are causes of increased red blood cell lysis?
- Polycythemia
- ABO incompatibility
- Rh incompatibility
- Infection, sepsis, UTI
What are the causes of decreased hepatic uptake?
- Immature Glucorynal transferase
- hypothyroidism
- Crigler Najjar syndrome
- Gilbert syndrome
What are the causes of increased enterohepatic circulation reabsorption?
-breast feeding jaundice and breast milk jaundice
What are the causes of conjugated hyperbilirubinaemia?
- Hepatitis
- Biliary artesia
- Choledochal cyst
