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Y3 paediatrics > approach to the yellow baby > Flashcards

approach to the yellow baby Flashcards

1
Q

what are the functions of the liver

A
  • synthetic function: proteins, enzymes
    • e.g. clotting factors
  • absorption and metabolism
    • bile for fat absorption; proteins and carbs
  • storage
    • e.g. glycogen, fat, protein
  • excretion and clearance of toxic products
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2
Q

what 4 things are included in a LFT

A

actually assess liver damage

  • bilirubin
    • total
    • split - direct (conjugated) and indirect (unconjugated)
  • ALT/AST - alanine aminotransferase, aspartate aminotransferase
  • alkaline phosphatase
  • gamma glutamyl transferase (GGT)
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3
Q

when would ALT/AST be elevated

A

hepatocellular damage - hepatitis

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4
Q

when would alkaline phosphatase and gamma glutamyl transferase (GGT) be elevated

A

biliary disease

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5
Q

tests to assess liver function

A

coagulation - prothrombin time (PT)/INR, APTT - liver’s production of clotting factors

albumin - synthetic function of liver

bilirubin - clearance of bile from liver

(blood glucose) - hypoglycaemia can be a clearance of liver failure

(ammonia) - can be elevated in liver failure

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6
Q

clinical manifestations of paediatric liver disease

A
  • jaundice
  • incidental finding of abnormal blood test
  • symptoms/signs of chronic liver disease
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7
Q

signs of chronic liver disease in children

A

head: encephalopathy, epistaxis

skin: jaundice,spider naevi, bruising and petechia

portal HT: varices , splenomegaly

abdo: hypersplenism, hepatorenal failure, ascites

peripheral: liver palms, clubbing, peripheral neuropathy, hypotonia

malnutrition: muscle wasting, loss of fat stores, rickets 2y to vit D deficiency

cholestasis: fat malabosorption, deficiency of fat soluble vitamins, pruritis, pale stools, dark urine

growth failure

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8
Q

what is jaundice

A

= yellow discolouration of skin and tissues due to accumulation of bilirubin

most common presentation of liver disease in children

usually most obvious in sclera, can also check when blanching skin (press finger over sternum and look at colour)

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9
Q

when does jaundice become visible

A

usually visible when total bilirubin >40-50umol/l

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10
Q

DDx for jaundice

A

beta-carotenaemia - high consumption of carotene high foods e.g. carrots

  • yellow discolouration of sclera is more likely to be jaundice as beta-carotenaemia only discolours skin and slcera will remain white
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11
Q

what is diagnosis of infant jaundice dependent on

A
  • bilirubin metabolism
  • age of infant
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12
Q

describe the process of bilirubin metabolism

A
  1. red cells reach end of their life and are ready to be broken down
  2. Hb is broken down - iron recycled to make new Hb, haem portion is broken down to make biliverdin
  3. free circulation biliverdin is converted by biliverdin reductase into unconjugated bilirubin
  4. unconjugated bilirubin is bound to albumin and transported to the liver
  5. in the liver is is conjugated w/ glucuronic acid bu UDP glucuronosyltransferase to make conjugated bilirubin
  6. conjugated bilirubin is excreted from the liver into the bile and then through the bile duct into the small intestine
  7. in the small intestine it is converted into urobilinogen which leaves in the stool as stercobilin (converted from urobilinogen by bacteria in the gut) or is excreted by the kidneys
  8. some of the reabsorbed urobilinogen from the gut goes back through the liver via enteropathic circulation and repeats the cycle
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13
Q

where are red cells broken down

A

reticular endothelial systems

  • spleen
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14
Q

is unconjugated bilirubin soluble

A

water insoluble - has to be transported bound to albumin

conjugated bilirubin is water soluble

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15
Q

which part of bilirubin metabolism does pre-hepatic jaundice affect

A
  • any cause of jaundice where the cause lies before the liver
  • XS bilirubin production
  • mostly unconjugated
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16
Q

which part of bilirubin metabolism does intra-hepatic jaundice affect

A
  • problem within the liver itself
  • liver isn’t conjugating bilirubin as well as it should be
  • not excreting bilirubin into the bile effectively
  • mixed picture of elevated conjugated and unconjugated bilirubin
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17
Q

which part of bilirubin metabolism does post-hepatic jaundice affect

A

aka cholestasis

  • bile can’t get out of liver into small bowel to be excreted
  • tends to be obstructive process, bilirubin is still getting to the liver and being conjugated but isn’t getting out
  • elevation of conjugated jaundice
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18
Q

when does early neonatal jaundice occur

A

early - <24hrs old

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19
Q

causes of early neonatal jaundice

A

ALWAYS PATHOLOGICAL

haemolysis, sepsis

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20
Q

when does intermediate neonatal jaundice occur

A

24hrs-2wks

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21
Q

causes of intermediate neonatal jaundice

A

physiological

breast milk

sepsis

haemolysis

22
Q

when does prolonged neonatal sepsis occur

A

>2wks

  • >3wks for preterm infants
23
Q

causes of prolonged neonatal sepsis

A

conjugated: extrahepatic obstruction - biliary obstruction, neonatal hepatitis
unconjugated: hypothyroidism, breast milk

24
Q

what is physiological jaundice

A

occurs after the first 24hrs

affects the vast majority of infants to some degree

25
Q

why does physiological jaundice occur

A

shorter RBC life span in infants - 80-90days

relative polycythaemia (high RBC count) - typical Hb 180-200

relative immaturity of liver function

  • more RBC breakdown, liver isn’t conjugating as quickly → jaundice

unconjugated jaundice, occurs AFTER first day of life

26
Q

why does physiological jaundice occur after the first day of life

A

takes time for RBC to break down and jaundice to build up

27
Q

why does breast milk jaundice occur

A

exact reason for prolongation of jaundice in breastfed infants is unclear

  • ? inhibition of UDP by progesterone metabolite → less conjugation → increased unconjugated jaundice
  • ? increased enterohepatic circulation → more reabsorption of bilirubin → higher levels in bloodstream
28
Q

what is breast milk jaundice

A

jaundice is more likely in breastfed babies than formula fed

unconjugated jaundice

can persist up to 12wks

29
Q

why is jaundice important to investigate

A

kernicterus

unconjugated bilirubin is fat soluble so can cross blood brain barrier

neurotoxic and deposits in brain

30
Q

early signs of kernicterus

A

encephalopathy

poor feeding

lethargy

seizures

31
Q

late consequences of kernicterus

A

serve choreioathetoid cerebral palsy

learning difficulties

sensorineural deafness

32
Q

what type of jaundice does kernicterus occur with

A

only high levels of unconjugated

33
Q

how to avoid kernicterus developing

A

phototherapy for unconjugated jaundice

  • visible light (450nm) wavelength, NOT UV, converts bilirubin to water soluble isomer (photoisomerisation)
  • threshold for phototherapy in infants guided by charts
34
Q

causes of haemolysis resulting in early/intermediate unconjugated infant jaundice

A

ABO incompatibility

rhesus disease

bruising/cephalhaematoma

red cell membrane defects e.g spherocytosis

red cell enzyme defects e.g. G6PD

35
Q

causes of abnormal conjugation resulting in early/intermediate unconjugated infant jaundice

A

Gilbert’s disease - common, mild

Crigler-Najjar syndrome - v. rare, severe, high rates of kernictus

36
Q

tests to exclude sepsis as a cause of jaundice

A

urine and blood cultures

TORCH screen

37
Q

tests to exclude haemolysis as a cause of jaundice

A

ABO incompatibility, rhesus disease - blood group, DCT

bruising/cephalhaematoma - clinical examination

red cell membrane defects e.g spherocytosis - blood film

red cell enzyme defects e.g. G6PD - G6PD assay

38
Q

tests to exclude abnormal conjugation as a cause of jaundice

A

Gilbert’s disease, Crigler-Najjar syndrome - genotype, phenotype

39
Q

prolonged jaundice - conjugated jaundice

A

conjugated jaundice in infants is always abnormal and always requires further investigation

40
Q

what is the most important test in prolonged jaundice

A

split bilirubin - determine whether it is conjugated or unconjugated

41
Q

causes of prolonged jaundice - biliary obstruction

A

biliary atresia - conjugated jaundice, pale stools

choledochal cyst - conjugated jaundice, pale stools

alagille syndrome - intrahepatic cholestasis, dysmorphism, congenital cardiac disease

42
Q

prolonged jaundice - stool colour

A

always assess stool colour

  • pale stools indicate obstructive process and pigment isn’t getting into stool
  • normal stool colour (yellow/green/brown) - good bile flow is intact
43
Q

3 things to remember about prolonged jaundice

A

conjugated jaundice in infants is always abnormal and always requires further investigation

always assess stool colour

assessment of prolonged infant jaundice is primarily targeted at diagnosing patients with biliary atresia early

44
Q

what is biliary atresia

A

congenital fibro-inflammatory disease of bile ducts → destruction of extra hepatic bile ducts

inflammation typically progresses proximally towards liver and leads to destruction of bile ducts

45
Q

presentation of biliary atresia

A

prolonged, conjugated jaundice

pale stools, dark urine

most common indication for liver transplantation in children

46
Q

why is it important to diagnose biliary atresia

A

progression to liver failure if not identified and treated

timely diagnosis critical as time to treatment determines prognosis

47
Q

treatment for biliary atresia

A

Kasai portoenterostomy

  • fibrous bile ducts are removed
  • distal end of small bowel taken up to liver surface and anastomosis created onto liver surface
  • bile drains directly into small intestine from liver
  • proximal end of small bowel attached to loop of small bowel to re-establish connection
48
Q

prognosis following Kasai portoenterostomy

A

success rate diminishes rapidly w/ age

best results if performed before 60 days (<9wks)

palliative rather than curative - will likely require liver transplant later in life

49
Q

investigations for biliary obstruction causes of prolonged jaundice

A

biliary atresia - split bilirubin, stool colour, US, liver biopsy

choledocal cyst - split bilirubin, stool colour, US

alagille syndrome - dysmorphism, genotype

50
Q

causes of prolonged jaundice - causes of neonatal hepatitis

A

alpha 1 antitrypsin deficiency

galactosaemia

tyrosinaemia

urea cycle defects

haemochromatosis

glycogen storage disorders

hypothyroidism

viral hepatitis and other infectious causes - hep B/C, toxoplasma, CMV, EBV, UTI septicaemia, meningitis

parenteral nutrition

51
Q

tests for causes of prolonged jaundice - causes of neonatal hepatitis

A

alpha 1 antitrypsin deficiency - phenotype/level

galactosaemia - GAL-1-PUT

tyrosinaemia - amino acid profile

urea cycle defects - ammonia

haemochromatosis - iron studies, liver biopsy

glycogen storage disorders - biopsy

hypothyroidism - TFTs

viral hepatitis - serology, PCR

parenteral nutrition - hx

Y3 paediatrics (45 decks)

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