Neonatal Hyperbilirubinemia Flashcards
Approximately what % of all term newborns and most preterm infants develop clinical jaundice
85%.
The term Severe Neonatal Jaundice. …?
cute bilirubin encephalopathy (ABE), kernicterus, ET, or jaundice-related death
How much bilirubin will produce by the normal newborn …?
A normal newborn produces 6 to 10 mg of bilirubin/kg/day, greater than the adult production of 3 to 4 mg/kg/day.
One gram of hemoglobin produces how much of bilirubin…?
34 mg
Etiology for Displacement of bilirubin from albumin..?
acidosis,
by drugs, such as ceftriaxone, or
by free fatty acids (FFAs) at high molar ratios of FFA:albumin may increase bilirubin toxicity.
Gilbert’s syndrome etiology …..?
Polymorphisms in the UGT1A1 gene due to differences in the number of thymine–adenine repeats in the promotor gene diminish the expression of the UGT1A1 enzyme and result in increased TB levels (Gilbert’s syndrome)
UGT activity in newborn as compared to adults …?
In term infants at 7 days of age, UGT activity is approximately 1% that of adults and
reaches adult levels only by 3 months of age.
HYPERBILIRUBINEMIA definition ..?
It is defined as a TB >95th percentile (on the hour-specific Bhutani nomogram)
severe hyperbilirubinemia and require evaluation …..?
- Onset of jaundice before 24 hours of age
- An elevation of TB that requires phototherapy
- Rate of rise in total serum bilirubin (TSB) or transcutaneous bilirubin (TcB) level of >0.2 mg/dL/hour
- Associated signs of illness such as lethargy, poor feeding, and temperature instability
- Jaundice persisting after 14 days in a term infant, high-colored urine, and pale stools
the most common cause of hyperbilirubinemia …?
Hemolytic disease
Crigler–Najjar syndrome due to
either absent UGT activity (type I) or reduced UGT activity (type II) results in severe hyperbilirubinemia.
the most common inherited disorder of bilirubin glucuronidation..?
Gilbert’s syndrome
Gilbert’s syndrome genetics ..?
Gilbert’s syndrome results from a mutation in the promoter region of the UGT1A1 gene, reducing the production of UGT
When Gilbert’s syndrome will present ..?
Although the Gilbert genotype alone is not associated with increased hyperbilirubinemia, severe hyperbilirubinemia can result when an affected newborn also has increased bilirubin production or increased enterohepatic circulation
Breast milk jaundice …?
occurs in about 2.4% of all infants.
Typically, it begins after the first 3 to 5 postnatal days, peaks within 2 weeks of age, and,
if breastfeeding is continued, gradually returns to normal levels over 3 to 12 weeks.
Mechanisms of bilirubin reduction by phototherapy…?
- The main mechanism is structural isomerization by light that irreversibly converts bilirubin to lumirubin, a more soluble substance that can be excreted into bile and urine without conjugation.
- Photoisomerization rapidly converts about 15% of the 4Z, 15Z bilirubin isomer to the less toxic 4Z, 15E form
- Photo-oxidation is a slow process that converts bilirubin to small polar products that are excreted in the urine and is the least important mechanism of bilirubin elimination
the most effective are characteristics of phototherapy units …?
- Light emission in the blue-green spectrum (460 to 490 nm), which includes the region (460 nm) where bilirubin most strongly absorbs light
- Irradiance of at least 30 μW/cm2/nm
- As close to the baby as possible (older recommendation of 45 cm should not be practiced)
- Illumination of maximal body surface area
- Shown to decrease TB during the first 4 to 6 hours of exposure
Bronze baby” syndrome
Bronze baby” syndrome, a dark bronze discoloration of the skin thought to be related to impaired excretion of photoproducts of bile pigment, may occur with phototherapy in infants with direct hyperbilirubinemia (cholestatic jaundice) and usually resolves gradually within a few weeks after phototherapy is discontinued
Intravenous immunoglobulin (IVIG)
Intravenous immunoglobulin (IVIG) has been used in infants with hemolytic disease caused by Rh or ABO incompatibility when TB continues to rise despite continuous intensive phototherapy or is within 2 or 3 mg/dL of the threshold recommended for ET
Immediately after a double volume ET (about 160 to 180 mL/kg), TB values are typically…?
half the value prior to the procedure
ET procedure replaces approximately WHAT PERCENTAGE of the circulating RBCs.
85%
Neurologic manifestations of bilirubin toxicity early phase..?
Signs are subtle and may include lethargy, hypotonia, highpitched cry, and poor suck.
Intermediate phase …?
hypertonia of extensor muscles (rigidity, opisthotonus, and retrocollis), oculogyric crisis, irritability, fever, and seizures. Some infants die in this phase. All infants who survive this phase are likely to develop chronic bilirubin encephalopathy (clinical diagnosis of kernicterus)
Advanced phase…?
Signs include pronounced opisthotonus and retrocollis, cry that can be weak or shrill, apnea, seizures, and coma. Affected infants die from intractable seizures or respiratory failure
