Jaundice Flashcards
What is sclera referring to?
White layer of eye that covers most of the eyeball.
What features are common in jaundice?
Yellow discolouration of the skin
May include the sclera and mucous membranes
Common and mild typically on the head, face and neck.
Why does physiological jaundice occur?
Physiological jaundice occurs as a result of the normal breakdown of red blood cells which contain fetal haemoglobin (fHb) that is no longer required. After the birth, the neonate’s liver takes over the by product of this breakdown of red blood cells-bilirubin and metabolism and excretion of this byproduct occurs in the babies urine.
How is bilirubin synthesised and metabolised?
In the neonate 75% of the bilirubin is a by-product of haemoglobin
This unconjugated bilirubin is conjugated by enzymes in the neonates liver to become more water soluble to be excreted into the bile or urine (via the kidneys)
What enzyme conjugates bilirubin in the liver to make it more water soluble for excretion?
Bilirubin is conjugated within the hepatocyte to glucuronic acid by a family of enzymes, termed uridine-diphosphoglucuronic glucuronosyltransferase (UDPGT).
What two vital ingredients are required for the conjugation of billirubin in the liver to become more water soluble for excretion?
oxygen and glucose
What two abnormal events can slow down the conjugation of billirubin and why?
Hypoxia- oxygen required for conjugation
Hypoglycaemia- glucose required for conjugation
What type of newborn gets physiological jaundice and when?
All neonates have a peak of unconjugated bilirubin on the third or fourth day of life which can cause physiological jaundice.
What enzyme deficiency on day 3-4 postnatally causes a reduced excretion of conjugated bilirubin?
glucuronyl transferase enzyme (GTE)
What is most common type of Jaundice? (Physiological, Breast Milk Jaundice, Pathological)
Most common physiological (60% full term, 80% preterm)
What is prehepatic jaundice?
caused by conditions that heighten your blood’s rate of hemolysis- Because the liver can only process so much bilirubin at once, bilirubin overflows into bodily tissues
What is Pathological jaundice?
Arises from factors that alter neonates usual processes
Can be mixed unconjugated and conjugated bilirubin
Hepatic or post hepatic (relating to the liver)
What is Breast Milk jaundice?
Hepatocellular (relating to or involving liver cells)
Unconjugated bilirubin
Why does Breast Milk Jaundice occur?
Breast milk jaundice most often occurs in the second or later weeks of life and can continue for several weeks. While the exact mechanism leading to breast milk jaundice is unknown, it is believed that substances in the mother’s milk inhibit the ability of the infant’s liver to process bilirubin.
What liver cells conjugate bilirubin?
Hepatocytes
What is water soluble bilirubin called?
Conjugated Bilirubin
Haemolysis is increased in neonates more than adults. True or False?
True
Why is Haemolysis increased in newborns vs adults? 2 reasons
Polycythemia (more RBC than adults)
FoetalHb makes RBCs more fragile – shorter life span (80-100 d vs 120 d)
What is Kernicterus?
a rare but serious complication of untreated jaundice in babies. It’s caused by excess bilirubin damaging the brain or central nervous system.
What type of Bilirubin can cause Kernicterus?
Unconjugated bilirubin can pass blood-brain-barrier and affect brain
Jaundice is not clinically apparent until the serum bilirubin (SBR) level is approx what umol/l?
80 umol/l
How does Early feeding for the neonate aid bilirubin excretion
Conjugated Bilirubin is excreted in the gut by way of biliary excretion (CG is stored in bile ducts after its production in the liver). Bile is only secreted to aid in food digestion (enzymes can breakdown fats for uptake by the body) so without food activating peristalsis, bile won’t be secreted, and bilirubin won’t convert to its final excreted forms (stercobilinogen and urobilin)
Bilirubin must bind with what to travel to the liver to be conjugated.
with albumin in the blood
Why does the sclera in the eye yellow first with jaundice?
Blood flow favours the head and trunk in neonates, so the head is visibly yellow first but the lipids in the eyes/sclera bind unconjugated bilirubin strongly, making it very apparent, early in neonates.
What is Stercobilinogen, where is it produced and its use?
produced in the small intestines/gut and responsible for the brown colour in faeces
What colour would baby’s stool be that has high levels of stercobilinogen?
Dark brown (like meconium but even after meconium has passed through)
What breaks down red blood cells?
Macrophages
What do macrophages release when breaking down red blood cells?
Hemoglobin
What happens to Heme in the breakdown of RBC?
Metabolises to become unconjugated bilirubin
How is unconjugated bilirubin delivered to the liver?
Its carried by albumin in the blood stream
Once at the liver what happens to unconjugated bilirubin?
It is picked up by liver hepatocytes and conjugates by enzyme UGT1A1 and excreted by hepatocytes to gall bladder and duodenum
Once newly formed conjugated bilirubin is excreted by liver hepatocytes to the gall bladder and duodenum what happens from then?
Most is excreted through bile which is released as baby feeds and is excreted in the bowel movements, some is unconjugated by an enzyme and reabsorbed into the blood stream to start again.
What is the term for conjugated bilirubin being turned back to unconjugated bilirubin and reabsorbed into the blood stream to start the cycle again?
Enterohepatic circulation
Would delayed cord clamping increase bilirubin levels in the neonate?
Yes-Higher erythrocytes/RBCs; potential for increased haemolysis as more blood from cord during DCC
Bilirubin is a waste product released during the breakdown of:
Erythrocytes
Pre-hepatic jaundice is caused by anything which causes an increased rate of haemolysis (breakdown of________):
Haem
Breastmilk can increase the incidence of jaundice because of:
Factors in breastmilk that increase unconjugated bilirubin
What are common causes of pathological jaundice?
Common pathologies: ABO incompatibility, Rhesus factor incompatibility
What are some rare causes of pathological jaundice?
Biliary atresia, Glucose-6-phosphate dehyrogenase (G6PD) deficiency
How should we manage physiological jaundice?
- Frequent feeds – 3 hourly day & night
- Show mother ways to wake baby up
- Assess output, stools and urine colour
What is Kramers Rule?
Five zones which assess jaundice levels- the lower the jaundice is from the head down- the more serious and higher bilirubin levels are present
Should we suggest placing baby in daylight?
There is no evidence that supports this practice. Risks outweigh any perceived advantage: high UV levels – sunburn and Melanoma development
When do you refer to a paediatrician?
Jaundice requires paediatric evaluation in the following situations and whenever there is a possibility that hyperbilirubinaemia may indicate or cause pathology.
When must we transfer care for jaundice immediately?
When jaundice is observed in the first 24 hours
What are the differences between early onset breastfeeding jaundice and late onset?
- early onset-feeding related (‘breastfeeding failure’ or ‘breastfeeding’ jaundice)
- ate onset: -constituents in breastmilk cause an increase in UCB in the body (‘breastmilk jaundice’)
What percentage of full term newborns develop physiological jaundice?
60%
What percentage of preterm newborns develop jaundice?
80%
Are formula fed or breastfed babies at more risk of developing jaundice?
Breastfed due to formula fed babies having larger volumes straight away vs breastfed.
What are some factors that increase the chances of physiological jaundice developing?
Dehydration, prematurity, traumatic birth, previous sibling with jaundice, macrosomic baby of a diabetic mother.
What does a midwife do if she suspects jaundice?
Assess the baby, put a care plan in place, test and refer if necessary.
