Neonatal Hyperbilirubinemia Flashcards Preview

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Flashcards in Neonatal Hyperbilirubinemia Deck (16)
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1
Q
When testing for jaundice, for lab tests you must order
A
BOTH Direct and Total Bilirubin
2
Q
Total bilirubin includes
A
Includes Direct and indirect

= TSB (total serum bilirubin)
TcB (total capillary bilirubin)
3
Q
Heme is converted to
A
biliverdin via heme oxygenate
(Fe2+ and CO are byproducts)

THEN, biliverdin is converted to bilirubin via biliverdin reductase
4
Q
Bilirubin is formed from _______ and is bound to _________
A
heme catabolism

albumin
5
Q
Bilirubin can cross BBB in
A
its free state
6
Q
In hepatocytes bilirubin binds to
A
Z-protein and Ligandin
7
Q
Bilirubin is conjugated with _________ by __________ to make it more water soluble
A
with glucuronic acid by the enzyme uridine diphosphate glucuronyl transferase
8
Q
Unconjugated bili crosses ________
A
placenta in fetus – conjugated by maternal liver
9
Q
Most conjugated bili is dumped in to
A
the gut – excreted by GI tract
(some is excreted into the urine)
10
Q
__________ further metabolizes conjugated bili
A
Bacteria flora
11
Q
__________ hydrolyzes bili back into unconjugated form
A
Beta-glucuronidase (intestinal enzyme)
12
Q
Neonates have excessive _______ and low ________
A
Beta-glucuronidase and low intestinal flora
13
Q
Risk factors for the development of hyperbilirubinemia in infants of 35 or more weeks gestation
A
-Elevated predischarge TSB or TcB levels
-jaundice observed in the first 24 hrs or prior to discharge
-Blood group incompatibility with positive direct antiglobulin test, other known hemodynamic disease (G6PD deficiency, hereditary spherocytosis)
-decreasing gestational age
-previous sibling with jaundice or who received phototherapy
-vacuum extraction during deliver, cephalhematoma or significant bruising
-Exclusive breastfeeding, particularly if nursing isn't going well and weight loss is excessive
-East Asian race
-Macrosomic infant or diabetic mom
-Maternal age over 25
-Male gender
14
Q
Physiologic Jaundice
A
-Unconjugated hyperbilirubinemia that occurs after the first postnatal day and can last up to 1 week
-Term infants peak in the first 3 to 5 postnatal days.
-Preterm infants peak at 5-7 days.
-If > than 15 at any time no longer physiologic
15
Q
During physiologic jaundice, bilirubin production is increased as a result of
A
elevated hematocrit and red blood cell volume per body weight and a shorter life span of the red blood cells.

-Infants also have immature hepatic glucuronyl transferase (UDP-GT)
16
Q
Pathogenesis of jaundice associated with breast feeding
A
-increased enterohepatic circulation of bilirubin
-decreased caloric intake
-less cumulative stool output and stools contain less bilirubin (compared to formula fed infants)
-increased intestinal fat absorption
-less formation of urobilin in GI tract
-increased activity of beta glucuronidase in breast milk
-decreased bilirubin conjugation (mutations of the UGT1A1 gene, Gilbert's syndrome--prolonged breast milk syndrome)