Jaundice Flashcards
bilirubin is derived from ___
the heme from old or damaged RBCs is broken down into bilirubin and iron
___ transports the bilirubin to the liver where it undergoes two enzymatic processes to conjugate it into a water-soluble form.
Albumin
Describe bilirubin clearance
- albumin transfer unconjugated bilirubin to liver
- Bilirubin undergoes 2 enzymatic processes to conjugate it into a water soluble form
- The liver then stores it as bile and excretes it into the intestine where it aids in fat digestion
*normal intestinal flora make conjugated bilirubin non-resorpable
What is is responsible for the yellow to green to brown color of stool.
bilirubin stored as bile in liver then excreted into intestintes where it aids in fat digestion
___ keeps the bilirubin in bile in its water-soluble form making it non-resorpable
The normal intestinal flora
Until the dual enzymatic process in the liver is completed, the bilirubin is __ and ___
unconjugated and fat-soluble.
In laboratory analysis, unconjugated bilirubin reacts with reagents ___, so on laboratory reports it will be referred to as__ bilirubin. Once the bilirubin is conjugated, it reacts ___ with laboratory reagents, so is referred to on laboratory reports as bilirubin.
indirectly
indirect
directly
direct
ALL newborns develop physiologic jaundice to some degree. It rarely rises above ___ of bilirubin, and has only ___ and ___, and causes no problems for the newborn.
13mg/dl
mild skin jaundice and scleral icterus
Why do all newborns have some degree of physiologic jaundice
- Infants are born with a high RBC count, to compensate for their somewhat hypoxic state in utero. These begin to breakdown fairly soon after birth so there is naturally a increased amount of bilirubin being produced
- increased fatty acid intake interferes with albumin transport, which is more of a problem for breast fed infants, but occurs to some degree with all infants.
- the second enzyme, UDP-glucuronyl transferase is somewhat slow in functioning in the initial days of life, so unconjugated bilirubin will build up in the serum
- The bile duct does not begin secreting immediately, so there is some degree of stasis that occurs at this level with conjugated bilirubin.
- the neonate intestine is a sterile environment until they have been feeding for a few days. Without the intestinal flora, the conjugated bilirubin in the bile is resorbed, leading to a increase in the total serum bilirubin.
____ intake interferes with albumin transport, which is more of a problem for breast fed infants, but occurs to some degree with all infants.
increased fatty acid
____ is somewhat slow in functioning in the initial days of life, so ___ bilirubin will build up in the serum.
the second enzyme, UDP-glucuronyl transferase
unconjugated
the neonate intestine is a sterile environment until they have been feeding for a few days. Without the intestinal flora, the ___ bilirubin in the bile is resorbed, leading to a ___
conjugated
increase in the total serum bilirubin.
Risk factors for neonatal jaundice
- Breastfeeding
- Prematurity
- Dehydration
- Asian ancestry- due to less amount of, or less effective UDP-glucuronyl transferase
- Hemolytic processes
- Maternal diabetes/ hypoglycemic infant
- Infection- poor bile excretion and increased RBC breakdown
- Obstructed bile duct (biliary atresia)
Increased fatty acids interfere with:
- albumin transport of bilirubin to the liver
- UDP glucuronyl transferase
*Fatty acids are high in breast milk
Describe why neonates can get break milk jaundice
- increased RBC breakdown
- fatty acids interfere w/ albumin transport of bilirubin to the liver and UDP glucuronyl transferase
- poor biliary excretion of conjugated bilirubin due to lack of breast milk in first 3 days of life leading to dehydration
___ is the leading cause of neonatal jaundice, and can lead to bilirubin levels high enough to require treatment
Breast milk jaundice
*Generally, we try, and are successful at keeping infants breastfeeding. We just have to play a waiting game, and be ready to provide treatment to bring the bilirubin levels down if necessary
Common causes of increased breakdown of RBC and the additional release of unconjugated bilirubin that can lead to pathologic neonatal jaundice
- Hemolytic Disease
- ABO incompatibility (MC)
- G6PD deficiency
- Extravascular blood (ie. cephalohematoma)
- Hereditary spherocytosis
- Significant tissue bruising during delivery
How do you determine if ABO incompatibility (hemolysis) is causing the neonatal jaundice
- In these cases, the mother is O+ and the baby is not.
- A Coombs test can tell you if the baby’s RBCs are carrying antibodies which mark them for destruction.
*-Indirect coombs- AB in serum, direct coombs- AB on RBC so immune system is going after it
**Mother has to be O+
G6PD deficiency most commonly occurs in who
is usually a disease of males of African or Mediterranean descent and the stress of birth, combined with this enzymatic deficiency, will result in hemolysis.
Causes of pathologic neonatal jaundice that results in high unconjugated or indirect bilirubin
- increased breakdown of RBC
- Decreased serum albumin (common in premature infants)
- Competitive albumin-binding (ie. sulfa drugs- MC w/ UTIs during preg.)
- infant hypoglycemia
- UDP glucuronyl transferase deficiency
If the infant had hypoglycemic episodes in the nursery, it will not be able to make the necessary amounts of ___
glucuronic acid (substrate)
Neonatal hypoglycemic occurs due to __ or __
maternal diabetes or infections in the infant.