Hyperbilirubinemia Flashcards
What is hyperbilirubinemia?
Elevated total serum bilirubin level
What is considered hazardous hyperbilirubinemia?
TSB > 30 mg/dL
What is bilirubin?
A byproduct of RBC destruction which releases heme-containing proteins
What is jaundice?
Yellow color caused by the deposit of bilirubin in the skin
What is acute bilirubin encephalopathy?
Bilirubin toxicity with symptoms correlated to elevated levels of unconjugated bilirubin
What are the phases of acute bilirubin encephalopathy?
Phase 1: lethargy, hypotonia
Phase 2: fever, retrocollis, hypertonia, opisthotonos, high pitched cry
Phase 3: shrill cry, hearing and visual impairment, athetosis, apnea, seizures, coma, death
What is kernicterus?
Irreversible, chronic sequelae of bilirubin toxicity; yellow staining of brain tissue caused by transfer of free bilirubin into brain cells
What is unconjugated bilirubin?
Indirect bilirubin, fat soluble, produced by RBC destruction
What is conjugated bilirubin?
Direct bilirubin, transformed by liver to water soluble form
What is free bilirubin?
Indirect bilirubin which is not bound to albumin
What is the normal bilirubin production in neonates?
8 – 10 mg/kg/day
How does bilirubin bind to albumin?
Bilirubin binds reversibly to albumin; each albumin molecule can bind ~2 molecules of bilirubin
What factors affect bilirubin binding?
- Amount of serum bilirubin
- Albumin levels
- Competition for binding sites
- Drugs such as salicylates, sulfa products
- Acidosis and hypoxemia
What causes kernicterus?
Transfer of free (unbound and unconjugated) bilirubin into brain cells
What is the role of hepatic ligandin?
Transports unconjugated (indirect) bilirubin into the hepatocyte
What is the enzyme responsible for conjugating bilirubin?
Uridine diphosphogluconurate glucuronosyltransferase (UGT)
What is enterohepatic recirculation?
Process where conjugated bilirubin can be broken down into unconjugated bilirubin in the intestine and reabsorbed
What are some causes of hyperbilirubinemia?
- Increased RBC volume
- Increased hematocrit
- Increased RBC destruction
- Infection (bacterial or viral)
- Red cell membrane defects
- RBC enzyme defects (e.g., G6PD deficiency)
- Delayed meconium passage
- Delayed feeding
What is G6PD deficiency?
One of the most important causes of hazardous hyperbilirubinemia; identifying infants is challenging
What is breast milk jaundice?
Hyperbilirubinemia that persists despite adequate intake and weight gain; can last up to 3 months
What are the risk factors for developing significant hyperbilirubinemia?
- Lower gestational age
- Jaundice in the first 24 h after birth
- Family history of phototherapy or exchange transfusion
- Exclusive breastfeeding with suboptimal intake
What characterizes physiologic (non-pathologic) jaundice?
Develops at > 24 hours of age; total bilirubin is < 12 mg%; peaks at day 3-4 (term) or 5-6 (preterm)
What defines pathologic or hazardous jaundice?
Appears at < 24 hours of age (term) or < 48 hours (preterm); persists beyond normal time frame; rate of rise > 0.2-0.3 mg% per hour
What is RhoGAM?
Anti-D human gamma globulin given to mothers to prevent production of anti-Rh(D) antibodies
What are the components of the diagnosis of hyperbilirubinemia?
- History (gestation, age of infant, onset of jaundice, birth history)
- Physical exam (color, tone, degree of jaundice)
- Labs (indirect and direct bilirubin levels, blood type)
What are the thresholds for beginning phototherapy?
Based on gestational age, neurotoxicity risk factors, and age of the infant in hours
What are the three types of chemical reactions that occur during phototherapy?
- Photoisomerization
- Structural isomerization
- Photo-oxidation
What are common side effects of phototherapy?
- GI hypermotility
- Lethargy or irritability
- Retinal damage
- Photosensitivity
What is a recommended way to protect the eyes of infants during phototherapy?
Protect eyes with patches
What are important considerations for infants receiving treatment during phototherapy?
Ensure adequate intake (weight, voids, stools)
What is the recommended method for feeding infants during phototherapy?
Breast feed, then pump and supplement with pumped breast milk or with formula
What substances should not be used with infants during phototherapy?
Do not use sterile water or glucose water
What is the gestational age range that indicates an infant is not full term?
35 to 37 weeks
What are some side effects of phototherapy?
- GI hypermotility: loose stools
- Lethargy or irritability
- Retinal damage
- Photosensitivity
- Potential cellular damage
- Hypocalcemia, thrombocytopenia
- Bronze color if high conjugated bilirubin level
When should phototherapy be discontinued?
When TSB has decreased by at least 2 mg/dL below the hour specific threshold at the start of phototherapy
What factors should be considered when deciding to stop phototherapy?
- Bilirubin level
- Age
- Feeds
- Stooling
- Other considerations
What is rebound hyperbilirubinemia?
Defined as a TSB concentration that reaches the phototherapy threshold for the infant’s age within 72-96 hours of discontinuing phototherapy
What is the recommended action after discontinuing phototherapy?
Check bilirubin 12-24 hours after discontinuation
What is the escalation of care threshold for exchange transfusion?
2 mg/dL below the exchange transfusion threshold
What should be done when the TSB falls below the escalation of care level?
Follow regular phototherapy guidelines
What is the volume of blood typically exchanged during an exchange transfusion?
(~160 mL/kg) plus tubing volume will reduce the TSB by 50%
What must be provided to all neonates discharged at less than 72 hours after birth?
Follow-up by a health care professional within 24 to 48 hours after discharge
What should be documented during discharge planning?
- Discharge exam
- Feeding
- Stooling
- Instructions
What is a key teaching point for discharge planning at 24 hours?
Detailed teaching regarding s/s of jaundice, feeding patterns, etc.
