Jaundice Flashcards
elevated levels of bilirubin in the serum
hyperbilirubinemia
yellowish discoloration of the skin and mucous membranes
jaundice
enzyme that liberates chelated iron from heme structure
heme oxygenase
indirect vs direct bilirubin
indirect = bilirubin-albumin complex (water insoluble)
direct bilirubin = conjugated bilirubin (water soluble)
enzyme the conjugates bilirubin with glucoronic acid
udp glucuronyl transferase
most common morbidity in the newborn period
bilirubin levels >12.8 mg/dl (physiologic jaundice)
jaundice = >5 mg/dl
neonatal vs adult metabolism values
production 6-8 mg/kg/d vs 3-4
rbc volume 16-18 mg% vs 12-14 mg%
rbc lifespan 90 d vs 120 d
neonatal vs adult bilirubin metabolism
lower concentration of albumin
lower concentration of enzyme transferase
large bilirubin pool in the meconium (1 g meconium = 1 mg bilirubin)
meconium starts to be excreted by ___
10-16 wks aog
characteristics of unconjugated (indirect) bilirubin
lipid soluble = neurotoxic
poorly soluble in water, non-polar
passes the bbb readily
albumin bound in plasma
characteristics of conjugated (direct) bilirubin
water-soluble
actively transported to biliary tree
neonatal cholestasis/cholestatic jaundice = >20% of total bilirubin is conjugated (>2 wks)
bilirubin levels in physiologic jaundice
3rd day: 7-7.5 mg%
3rd-5th day: peak
5-th-7th day: < 2 mg/dl
onset and factors for breastfeeding jaundice
onset: 3-4 days of life
factors: inadequate nursing, decreased stool output, increased enterohepatic circulation
jaundice where the onset is at the end of the first week of life
breastmilk jaundice
what to do if baby is still jaundiced at 1-2 mos
- check if direct hyperbilirubinemia
- if direct >20% total or >2 mg/dl = neonatal cholestasis
- if direct is less + no hemolysis = breastmilk jaundice
causes of pathologic jaundice
overproduction of bilirubin
undersecretion of bilirubin
mixed
levels of hyperbilirubinemia
significant: >95th percentile, >17 mg/dl at 72 hrs
severe: 99th percentile, >20 mg/dl
extreme: >99.5th percentile, >25 mg/dl
causes of overproduction of bilirubin
increased rbc breakdown due to
- hemolytic disorders (rh/abo, genetic, drugs)
- extravasated blood
- polycythemia
- exaggerated enterohepatic circulation (reduced peristalsis, mechanical obstruction)
causes of undersecretion of bilirubin
decreased hepatic uptake
decreased bilirubin conjugation
impaired transport of conjugated bilirubin out of hepatocyte
obstruction to bile flow
mixed causes of pathologic jaundice
intrauterine infection (torch, syphilis, hepa/b)
postnatal infections
multi-system disorders
complications of hyperbilirubinemia in newborns
- bilirubin toxicity
- kernicterus
- active bilirubin encephalopathy (abe)
- bilirubin-induced neurologic dysfunction (bind)
- chronic bilirubin encephalopathy (cbe)
- subtle bilirubin encephalopathy
important cause of cerebral palsy, developmental delay, or hearing impairment and the most preventable cause of cerebral palsy
bilirubin toxicity
pathologic findings of bilirubin toxicity in the brain (staining/necrosis)
kernicterus
bilirubin induces lipid peroxidation -> neuroinflammation and mitochondrial failure (loss of atps) -> apoptosis and neuronal death
phases of acute bilirubin encephalopathy
first days and weeks following hyperbilirubinemic event
1: poor sucking, lethargy, stupor, hypotonia, seizure
2: middle of the week, alternating hyper/hypotonia, opisthotonus, fever, upward gaze paralysis
3: after 1 week, hypertonia
abe tests and imaging results
abnormal baer (brainstem auditory evoked response) lesions in globus pallidum on mri
the subtle form of brain injury due to the effects of bilirubin toxicity but comprising less obvious neurologic manifestations
bilirubin induced neurologic dysfunction
bind scoring system
mental status
muscle tone
cry
=6 reversible
7-9 irreversible
clinical triad of post icteric sequelae in chronic bilirubin encephalopathy (permanent)
4E: EXTRAPYRAMIDAL, EYES, EARS, EEE (smile)
extrapyramidal abnormalities (athetoid cp and spasticity)
deafness or diminished hearing
impaired upward gaze
dental enamel dysplasia
t/f for those who have abe, 50% will die and those who will survive will have bind
false, cbe
most preventable cause of cerebral palsy
chronic bilirubin encephalopathy
manifestation of subtle bilirubin encephalopathy in school aged children/adults
subtle bilirubin encephalopathy
clinical manifestations of subtle bilirubin encephalopathy
isolated hearing loss
gaze abnormality
gait abnormality
why is bilirubin produced?
- iron salvage pathway: carbon monoxide, iron, biliverdin
- potent scavenger of peroxyl radicals
- inhibit the effects of mutagens
- anti-oxidants
basic principles of preventing severe hyperbilirubinemia
- recognize risk factors
- vigilant in-hospital monitoring
- post-discharge monitoring
- adequate breastfeeding support
- parenteral and nursing education
what to check to prevent sever hyperbilirubinemia
- risk factors
- jaundice
- follow up 48-72 hrs if discharged <72 hrs
- einc and lactation counselors
- written and oral information in the nicu
clinical assessment of jaundice after birth
visual assessment: monitor as a vital sign at 8h
bilirubin testing in nbs
check risk factors (late preterm, bruising, race)
t/f if the baby is jaundiced, you can’t reliably estimate the bilirubin levels
true
transcutaneous bilirubin can be tested on __
> 35 weeks
postnatal age >24 hrs
indications for serum bilirubin test
tcb reading > 250 mg/dl
jaundice in first 24 hrs
<35 wks aog
t/f forehead tcb has better correlation efficient
false, chest has better due to less exposure to sunlight
risk factors for the development of severe bilirubinemia in infants >35 weeks
age 35-36 wks exclusive breastfeeding abo incompatibility g6pd deficiency east asian race
risk stratification depends on ___ approach
hour of life approach
t/f late preterm babies act like term babies
false, they can act like preterm despite having the size of a term baby
have an 8 fold increase in developing tsb of >20 mg/dl
t/f hyperbilirubinemia in east asians are more prevalent, more pronounced, and more protracted
true
indications for phototherapy
24 hol > 12
48 hol >15
72 hol > 18
indications for exchange transfusion
24 hol > 19
48 hol > 22
72 hol > 24
>72 hol >/= 25
process where water insoluble bilirubin is converted into water soluble forms without conjugation in the liver
phototherapy
what is photooxidationi
bleaching reaction where oxidation of bilirubin into polar and water soluble products is done
what is photoisomerization
configurational (fast/major)
structural: form lumirubin, irreversible (slow)
ideal wavelength of phototherapy
450 nm (blue)
t/f circumferential therapy has more exposure, but conventional has less treatment failures
true
a cheaper phototherapy alternative for low resource areas
led phototherapy
t/f turning is necessary when doing phototherapy
false, there’s no difference
t/f there is a difference between continuous and intermittent phototherapy
false, no difference
if bilirubin is ___, they can carry their child to the wards and still do intermittent phototherapy
<20 mg/dl
t/f sunlight exposure can be done to the baby
false, aap recommends against it. sunlight exposure 6-9 am daily in first week of life is ok
avoid 10 am - 2 pm sun exposure
exchange transfusion can decrease bilirubin by ___
50%
exchanging blood of the infant with type o or o-
t/f phototherapy can be shortened and less exchange transfusions can be done if ivig is done with phototherapy
true
a lipid reducing substance that can reduce total bilirubin
clofibrate
drug that can induce glucuronyl transferase as ancillary therapy
phenobarbital
- take 5-7 days to effect
- prophylactic and not sued in severe levels
inhibits heme oxygenase
tin-mesoporphyrin
