Hyperb Flashcards
What enzyme converts indirect bilirubin into direct bilirubin?
Glucuronyl transferase.
What pigment gives feces its color and is excreted in urine?
Stercobilin (feces); Urobilinogen (urine).
What bilirubin levels make jaundice visible on sclera and face?
2-3 mg/dL (34-51 μmol/L) on sclera; 4-5 mg/dL (68-86 μmol/L) on face.
What are the mechanisms of hyperbilirubinemia?
Increased production, Decreased hepatic uptake, Decreased conjugation, Impaired excretion, Impaired bile flow (cholestasis), Increased enterohepatic circulation.
What are the types of hyperbilirubinemia?
Physiologic (2-4 days), Breast milk jaundice (7 days-2 weeks), Pathologic (within 24 hours).
What is kernicterus?
Brain damage caused by unconjugated bilirubin deposition in the basal ganglia and brain stem nuclei.
What are definitive treatments for hyperbilirubinemia?
Phototherapy and exchange transfusion.
How does phototherapy help treat hyperbilirubinemia?
It converts unconjugated bilirubin into water-soluble forms excreted rapidly by liver and kidneys.
What happens during an exchange transfusion?
Small amounts of blood are replaced through an umbilical vein catheter to remove hemolyzed RBCs and antibodies.
What is physiologic jaundice?
A transient elevation of unconjugated bilirubin occurring after 24 hours of age due to fetal polycythemia and liver immaturity.
Why does unconjugated bilirubin rise in physiologic jaundice?
Because of inadequate liver enzyme glucuronyl transferase to conjugate bilirubin and promote stool excretion.
When does physiologic jaundice resolve?
It declines to less than 2 mg/dL by 6 to 7 days of age.
How does early morning sunlight help physiologic jaundice?
Exposure between 8 a.m. and 10 a.m. for 30 minutes to 1 hour speeds resolution.
Why do breastfed babies have exaggerated jaundice?
Breast milk hormone pregnanediol may inhibit glucuronyl transferase, reducing bilirubin conjugation after 7 days.
What is pathologic jaundice?
An elevation of unconjugated bilirubin occurring within the first 24 hours or rising more than 0.5 mg/dL per hour.
What is the unconjugated bilirubin level for pathologic jaundice?
Greater than 13 mg/dL.
What are the criteria for pathological jaundice?
- Clinical jaundice within 24 hours of life, 2. Serum bilirubin increase > 5 mg/dL/day, 3. Total serum bilirubin > 12.9 mg/dL, 4. Direct bilirubin > 1.5-2 mg/dL, 5. Jaundice persistence for 7-10 days in term or 2 weeks in preterm infants.
What are common causes of pathologic jaundice?
- Blood incompatibility, 2. ABO/Rh incompatibility, 3. Prematurity, 4. Fetal polycythemia, 5. Maternal infection, 6. Swallowed maternal blood, 7. Cephalhematoma, 8. Fetal small-bowel obstruction.
What does phototherapy do?
It uses high-intensity UV light to convert fat-soluble unconjugated bilirubin into water-soluble conjugated bilirubin.
What is the goal of phototherapy?
To keep serum bilirubin levels below neurotoxic levels and prevent kernicterus.
What factors affect phototherapy effectiveness?
Wavelengths, distance between lights and infant (45-60 cm), and amount of skin exposed.
What are the types of phototherapy based on duration?
- Continuous (only interrupted for essential care), 2. Intermittent (e.g., 6 hours on/6 hours off).
What are the types of phototherapy units?
- Conventional overhead unit, 2. Fiberoptic light system/device (Biliblanket and Wallaby).
What is the desired irradiance level for conventional units?
5 to 6 microwatts per square centimeter per nanometer.
What is the desired irradiance level for fiberoptic systems?
8 to 10 microwatts per square centimeter per nanometer.
What are the benefits of fiberoptic devices like the Wallaby blanket?
They deliver high-intensity light without UV/IR radiation, allow 24-hour continuous treatment, and provide more skin exposure.
