Causes of Jaundice ✅ Flashcards
1
Q
What can the causes of hyperbilirubinaemia be divided into?
A
- Increased bilirubin production due to high red cell turnover
- Delayed bilirubin clearance
- Conjugated hyperbilirubinaemia
2
Q
What forms of bilirubin clearance can be delayed?
A
- Conjugation
- Biliary excretion
- Faecal/urinary elimination
3
Q
What are the causes of high red cell turnover?
A
- Physiological
- Polycythaemia
- Immune haemolysis
- RBC enyzme defects
- RBC membrane abnormalities
- Other causes of haemolysis
- Haematomas
- Maternal diabetes
4
Q
Why might red cell turnover be high physiologically in a neonate?
A
High haemoglobin and red cell mass at birth and short RBC lifespan
5
Q
What might cause immune haemolysis in a neonate?
A
Rb/ABO/other isoimmunisation
6
Q
Give 2 examples of RBC enzyme defects
A
- Glucose-6-phosphate dehydrogenase (G6PD) deficiency
- Pyruvate kinase deficiency
7
Q
Give 2 examples of RBC membrane abnormalities?
A
- Hereditary spherocytosis
- Hereditary elliptocytosis
8
Q
Give 2 examples of causes of haematoma that can lead to jaundice in neonates
A
- Extensive bruising
- Cephalohaematoma
9
Q
Give an example of another cause of haemolysis that can cause jaundice in neonates?
A
Sepsis
10
Q
What are the causes of delayed bilirubin clearance?
A
- Gilbert’s syndrome
- Decreased activity of glucuronyltransferase enzyme
- Drugs needing conjugation for excretion
- Increased enterohepatic circulation
11
Q
What happens in Gilbert’s syndrome?
A
There is a poor uptake of bilirubin by hepatocytes
12
Q
What can cause decreased activity of glucuronyltransferase enzyme?
A
- Genetic
- Hypoxia
- Infection
- Thyroid deficiency
- Hypothermia
- Prematurity
13
Q
Give a genetic cause of decreased activity of glucuronyltransferase enzyme
A
Crigler-Najjar syndrome
14
Q
Why might drugs needing conjugation for excretion cause delayed bilirubin excretion?
A
They compete for transferase enzymes
15
Q
What can cause increased enterohepatic circulation?
A
- Prolonged gut transit time
- Delayed passage of meconium
- Poor enteral feeding
- Prematurity
- Antibiotic treatment
16
Q
What can cause conjugated hyperbilirubinaemia in neonates?
A
- Congenital infections
- Neonatal hepatitis
- Obstructive
- Parenteral nutrition induced cholestasis
17
Q
What are the obstructive causes of conjugated hyperbilirubinaemia in neonates?
A
- Biliary atresia
- Choledochal cyst
18
Q
What is physiological jaundice?
A
Common, generally harmless jaundice occurring a high proportion of newborn babies in the first weeks of life for which there is no underlying cause
19
Q
What kind of hyperbilirubinaemia is seen in physiological jaundice?
A
Unconjugated
20
Q
What is the normal cord blood level of unconjugated bilirubin?
A
20-35µmol/L
21
Q
What usually happens to levels of bilirubin in the first few days of life?
A
They rise by less than 85µmol/L/day
22
Q
When does jaundice become clinically apparent?
A
When serum bilirubin is 80-90µmol/L
23
Q
When do bilirubin levels peak after birth in term infants?
A
Day 4-5
24
Q
When do bilirubin levels peak after birth in preterm infants?
A
Day 7-8
25
Who is more likely to develop physiological jaundice?
Breastfed babies
26
Why are breastfed babies more likely to develop physiological jaundice than formula fed babies?
Pathogenesis unclear, but proposed mechanisms;
- Increased ß-glucuronidase in breast milk
- High free fatty acid in breast milk
- Certain factors in breast milk may inhibit the enzyme responsible for conjugation the liver
- Inadequate milk intake
27
Why does the increased beta-glucuronidase in breast milk increase the risk of jaundice?
It can increase enteric absorption of bilirubin and hence the hepatic bilirubin load
28
Why does the high free fatty acid in breast milk increase the risk of jaundice?
It may compete for albumin binding sites for transport to the liver
29
How does inadequate milk intake lead to jaundice in breastfed babies?
Leads to sluggish gut action which increases enterohepatic circulation of bilirubin
30
Why do formula-fed babies have lower bilirubin levels?
Due to increased clearance of bilirubin from the gut
31
When does jaundice in term infants resolve?
Usually by 2 weeks of age
32
When does jaundice in preterm infants resolve?
Usually by 3 weeks
33
How long might jaundice persist in breastfed infants?
4-10 weeks
34
Should breastfeeding be continued in jaundiced infants?
Yes
35
What are the types of haemolytic disease of the newborn?
- Rh incompatibility
| - ABO incompatibility
36
What is rhesus haemolytic disease?
When there is incompatibility of the Rh blood group between the mother and fetus
37
What are the potential antigens in the Rh blood group?
- D
- C
- Kell
38
When can rhesus haemolytic disease occur, in terms of the blood groups of the mother and fetus?
If the mother is rhesus negative and the baby is rhesus positive
39
Why might a rhesus negative mother have a rhesus positive child?
If the child inherited the antigen from it's father
40
What kind of antibodies can the mother generate against the baby in rhesus haemolytic disease?
IgG
41
Where are antigens generated in rhesus haemolytic disease?
In the mothers bloodstream
42
How does IgG generated in the mothers bloodstream get to the baby in rhesus haemolytic disease?
It crosses the placenta
43
What happens when maternal IgG against crosses the placenta in rhesus haemolytic disease?
It causes fetal red cell haemolysis
44
What can fetal red cell haemolysis lead to in rhesus haemolytic disease?
- Jaundice
- Anaemia
- Hydrops
- Hepatosplenomegaly
45
Can rhesus haemolytic disease occur in the first pregnancy?
Occasionally
46
Why does rhesus haemolytic disease not usually occur in the first pregnancy?
As the mother needs to be sensitised to the rhesus-positive antigen, which usually occurs during the first pregnancy
47
What causes sensitisation of the mother to rhesus-positive antigen in rhesus haemolytic disease?
Feto-maternal haemorrhage
48
When does feto-maternal haemorrhage most commonly occur?
During delivery
49
Other than delivery, when might feto-maternal haemorrhage occur?
- Miscarriage
- Placental abruption
- Amniocentesis
- Chorionic villus sampling
50
When can rhesus haemolytic disease occur in a first pregnancy?
If the mother has been sensitised, e.g. from blood transfusion
51
What does the prenatal management of rhesus haemolytic disease involve?
- Monitoring of antibody levels
| - Referral to specialist centre if indicated
52
How can fetal rhesus genotype be determined?
Non-invasively by cell free fetal DNA analysis in maternal serum
53
How can fetal anaemia be monitored?
- Serial ultrasound scanning of middle cerebral artery Doppler waveform
- Measurement of fetal haematocrit from cordocentesis
54
What may be necessary in the prenatal management of rhesus haemolytic disease?
Intrauterine blood transfusion
55
What is required after birth in rhesus haemolytic disease?
Close bilirubin and haemoglobin monitoring
56
Why is close bilirubin monitoring required after birth in rhesus haemolytic disease?
Bilirubin level may rise very rapidly to dangerously high levels
57
Why has rhesus D alloimmunisation become rare?
As maternal blood group and antibody status is routinely tested, and if rhesus negative mothers are given anti-D IgG immunoglobulin
58
What does anti-D IgG immunoglobulin do?
Clears any felt red blood cells that may have leaked into the maternal circulation
59
How has the use of anti-D immunoglobulin changed the type of rhesus haemolytic disease that occurs?
Most cases are now anti-cell and anti-c
60
What is the difference between rhesus haemolytic disease caused by anti-Kell and anti-c compared to anti-D?
Anti-Kell and anti-c lead to much less severe fetal anaemia and hyperbilirubinaemia
61
What are the types of haemolytic disease of the newborn?
- Rh incompatibility
| - ABO incompatibility
62
When does ABO incompatibility arise, in terms of the blood group of the mother and fetus?
When a mother with blood type O has a fetus with a different blood type (A, B, or AB)
63
What kind of antibodies are the anti-A/anti-B produced in ABO incompatibility?
IgG
64
Is hyperbilirubineamia more severe in ABO incompatibility or rhesus haemolytic disease?
Rhesus haemolytic disease
65
Why is hyperbilirubinaemia less severe in ABO incompatibility?
As fetal RBCs express low ABO blood group antigens compared with adult levels
66
When is the onset of haemolysis and jaundice in ABO incompatibility?
After birth
67
How is ABO incompatibility diagnosed?
Direct antibody test is positive
68
What is the most common cause of severe neonatal jaundice and kernicterus worldwide?
G6PD deficiency
69
What is G6PD deficiency?
An X-linked recessive disorder characterised by low levels of glucose-6-phosphate dehydrogenase
70
What is the function of G6PD?
It is involved in red blood cell metabolism
71
Is G6PD deficiency more common in males or females?
Male s
72
Why is G6PD deficiency more common in males?
Due to it's X-linked inheritance
73
How might carrier females be affected with G6PD deficiency?
They may have a milder form
74
Why might carrier females have a milder form of G6PD deficiency?
As a result of lyonization
75
What ethnicity is G6PD more common in?
- Mediterranean
- Middle or Far Eastern
- African
76
What might trigger patients with G6PD deficiency to haemolyse?
A number of stressors, e.g.;
- Infection
- Certain medications
- Fava beans
77
How is G6PD deficiency diagnosed?
By measuring G6PD activity in RBCs
78
What causes Crigler-Najjar syndrome?
Deficiency of the enzyme uridine diphosphate glucuronyl-transferase (UGT)
79
What is the inheritance of Crigler-Najjar syndrome?
Autosome recessive
80
When does Crigler-Najjar syndrome present?
In the early neonatal period
81
How does Crigler-Najjar syndrome present?
Rapid rise in serum bilirubin to very high levels despite phototherapy
82
What can develop as a result of the jaundice in Crigler-Najjar syndrome?
Kernicterus
83
Is type 1 or type 2 Crigler-Najjar syndrome more severe?
Type 1
84
What are the peak bilirubin levels in type 1 Crigler-Najjar syndrome?
Up to 850µmol/L
85
Can Gilbert's syndrome cause severe unconjugated hyperbilirubinaemia?
It can contribute
86
What % of the population is homozygous for Gilbert's syndrome?
5-10%
87
What % of the population is heterozygous for Gilbert's syndrome?
40%
