8: 6-day-old female with jaundice Flashcards
Newborn Bilirubin Physiology
most (~75%) of the bilirubin produced in the healthy newborn comes from physiological breakdown of red blood cells.
At high levels, unconjugated bilirubin unbound to albumin
can cross the blood-brain barrier and cause neurologic toxicity.
Acute bilirubin encephalopathy occurs in the first few weeks of life.
- -Initial signs include poor suck, high-pitched cry, hypotonia, lethargy, seizures
- -Later signs include extensor hypertonia, opisthotonus (abnormal posturing that involves rigidity and severe arching of the back, with the head thrown backward)
Kernicterus
- -pathological term used to describe staining of the basal ganglia and cranial nerve nuclei by bilirubin.
- -also describes the chronic clinical condition that results from the toxic effects of high levels of unconjugated bilirubin.
Kernicterus results in abnormalities in
tone and reflexes, choreoathetosis, tremor, oculomotor paralysis, sensorineural hearing loss and cognitive impairment.
In the setting of a significantly elevated serum bilirubin (e.g > 20-25 mg/dL), the following are risk factors for toxicity:
- Hemolysis (e.g. isoimmune hemolytic disease, G6PD deficiency)
- Asphyxia
- Significant lethargy
- Temperature instability
- Sepsis
- Acidosis
- Albumin < 3.0 g/dL
Physiologic Jaundice definition
- total bilirubin level ≤ 15 mg/dL (≤ 257 μmol/L) in full-term infants who are otherwise healthy and have no other demonstrable cause for elevated bilirubin.
- Almost all newborn infants have hyperbilirubinemia, but it is benign and self-limited.
Numerous factors promote the increased enterohepatic circulation that results in physiologic jaundice:
- Increased bilirubin production (from the breakdown of the short-lived fetal red cells)
- Relative deficiency of hepatocyte proteins and UDPGT
- Lack of intestinal flora to metabolize bile
- High levels of β-glucuronidase in meconium
- Minimal oral (enteral) intake in the first 2-4 days of life, resulting in slow excretion of meconium (especially common with breastfed infants).
Jaundice Associated with Breastfeeding 1/2
- Happens early in the first week of life and occurs when the milk supply is relatively or absolutely low, resulting in limited enteral intake.
- this may be referred to as a “lack-of-breast milk jaundice” or “breastfeeding-associated jaundice.”
- The low intake results in decreased gastrointestinal motility that in turn promotes retention of meconium.
- The β-glucuronidase in meconium deconjugates bilirubin and the unconjugated bilirubin is reabsorbed via the enterohepatic circulation, causing an elevation of serum levels.
- Occasionally, persistently low vol of breast milk can cause the neonate to become dehydrated and malnourished. difficult to distinguish f/m physiologic jaundice.
Jaundice Associated with Breastfeeding 2/2
- Begins in the first 4 to 7 days of life but may not peak until about 10 to 14 days.
- Not the result of low breast milk volume.
- While the cause is not completely understood, one explanation is that β-glucuronidase present in breast milk deconjugates bilirubin in the intestinal tract; the unconjugated bilirubin is then reabsorbed via enterohepatic circulation.
- Breast milk jaundice can persist for up to 12 weeks, but total bilirubin concentration rarely, if ever, reaches concerning levels.
Etiologies of early newborn jaundice: Hemolysis
- Ab-positive hemolysis is labeled “direct Coombs” or “direct antibody test (DAT)” positive. The m/c forms of ab-positive hemolysis include:
- -Rh incompatibility (mother is Rh-negative and baby is Rh-positive)
- -ABO incompatibility (mother is type O and baby is type A or B)
- -Incompatibilities with minor blood group antigens (much less common)
- Ab-negative hemolysis occurs in infants who have rbc membrane defects (e.g., spherocytosis) or rbc enzyme defects (G6PD or pyruvate kinase deficiency).
Etiologies of early newborn jaundice: Non- hemolytic red cell breakdown
- Inc bilirubin production and development of jaundice and occurs in a variety of conditions, inc:
- –Extensive bruising from birth trauma
- –Large cephalohematoma or other hemorrhage (e.g., intracranial)
- –Polycythemia
- –Swallowed blood (large amounts) during delivery
Etiologies of early newborn jaundice: Other Causes aka Metabolic errors
- Crigler-Najjar syndrome type 1 and type 2
- Gilbert Syndrome is a much less severe but more common cause of unconjugated hyperbilirubinemia than Crigler-Najjaar.
- Galactosemia and hypothyroidism
Etiologies of early newborn jaundice: Neonatal sepsis
While sepsis can lead to jaundice, jaundice as the only sign of sepsis is rare.
Etiologies of early newborn jaundice: Congenital Infection
- In utero exposure to one of the TORCH infections can lead to jaundice.
- Physical findings may include hepatosplenomegaly, microcephaly, and/or rash.
successfully breastfed baby
- -typically nurses 8-12 times in 24 hours.
- -Feedings may initially last up to 60 minutes but gradually become shorter in duration, ~10-15 minutes at each breast. (Increasingly frequent or consistently lengthy feeding sessions may indicate a problem, especially if the infant is not gaining weight.)
