Hyperbilirubinemia Flashcards
Definition of hyperbilirubinemia?
total serum bilirubin greater than the 95th percentile on the neonate’s given nomogram
Bilirubin pathway in the body
Bilirubin is produced from the breakdown of hemoglobin from red blood cells. It is then bound to albumin and transported to the liver where it is taken up by hepatocytes. These hepatocytes catalyze the unconjugated bilirubin into conjugated bilirubin, making it more water-soluble. This allows the bilirubin to be secreted into the bile, which travels via the bile duct into the digestive tract. It is then excreted.
What is the enterohepatic circulation?
In babies, there is a special enzyme in the intestines that allows deconjugation of the conjugated bilirubin, turning it back into unconjugated. This allows it to be reabsorbed and recycled into circulation.
What is it called when bilirubin crosses the BBB and acts as a neurotoxin?
bilirubin-induced neurologic dysfunction (BIND)
What are the 3 phases of acute bilirubin encephalopathy (ABE) & their symptoms?
1) first phase: hypotonia, sleepiness, poor suck
2) intermediate phase: high pitched cry, inconsolable, febrile, hypertonic (retrocollis, opisthotonos on stimulation)
3) advanced phase: apnea, inability to feed, persistent retrocollis and opisthotonos, seizures, coma
What percentage of total bilirubin should conjugated bilirubin be before being worried?
<10%
Consequences of CBE/kernicterus?
cerebral palsy, hearing loss, gaze abnormalities, dental dysplasia, developmental delay and mental deficiency
Maternal risk factors?
ABO/Rh incompatibility, drugs (diazepam, oxytocin), GDM, difficulty BF, maternal age >25, Asian/European/Native American ethnicity
Neonatal risk factors?
prematurity, birth trauma, drugs, excessive weight loss, TORCH, infrequent feedings/dehydration, polycythemia, previous sibling with jaundice, delayed meconium
When does physiologic jaundice show and resolve by?
manifests itself at the 2nd or 3rd day of life and typically resolves by about the 7th day
Cause of physiologic jaundice?
increased breakdown of RBCs, immature liver unable to conjugate the bilirubin at a fast enough pace, enterohepatic circulation
Difference between breastmilk and breastfeeding jaundice?
Breastfeeding jaundice is from dehydration caused by a lack of milk production or intake. Breastmilk jaundice is when natural substances found in the breastmilk begin inhibiting the conjugation activity of a key enzyme in the liver
2 main causes of unconjugated bilirubinemia?
1) increased production
2) decreased clearance
Causes of increased production/hemolysis? + what tests would you do
1) ABO/Rh incompatibility [DAT/Coombs]
2) RBC defects – spherocytosis, G6PD or pyruvate kinase deficiency, thalassemia [CBC, diff, peripheral blood smear]
3) Sepsis [CBC, culture, CXR, LP]
4) Cephalohematoma
Causes of decreased clearance?
1) Crigler Niger syndrome
2) Gilbert’s syndrome
