3.1 Which of the following decreases the risk of neurologic damage in a jaundiced
newborn?
A. Acidosis
B. Displacement of bilirubin from binding sites by drugs such as sulfisoxazole
C. Hypoalbuminemia
D. Sepsis
E. Maternal ingestion of phenobarbital during pregnancy
3.2 An 8-day-old infant continues to have jaundice which was first noted on the
second day of life; his latest total and direct bilirubin levels are 12.5 and
0.9 mg/dL, respectively. The baby and the mother have type O positive blood,
the direct and indirect Coombs tests are negative, the infant’s reticulocyte count
is 15%, and a smear of his blood reveals no abnormally shaped cells. He is
bottle-feeding well, produces normal stools and urine, and has gained weight
well. Which of the following remains in the differential diagnosis?
A. Gilbert syndrome
B. Disseminated intravascular coagulation (DIC)
C. Spherocytosis
D. Polycythemia
E. An undiagnosed blood group isoimmunization
3.3 Hyperbilirubinemia associated with Crigler-Najjar syndrome type I is caused
by which of the following?
A. Increased production of bilirubin
B. Impaired conjugation of bilirubin
C. Deficient hepatic uptake of bilirubin
D. Severe deficiency of uridine diphosphate glucuronosyltransferase
E. Glucose-6-phosphate dehydrogenase deficiency
3.4 A 30-hour-old full-term infant has facial and chest jaundice. He is breastfeeding well and has an otherwise normal examination. His bilirubin level is
15.5 mg/dL. Which of the following is the most appropriate course of action?
A. Recommend cessation of breast-feeding for 48 hours and supplement
with formula.
B. Start phototherapy.
C. Wait for 6 hours and retest the serum bilirubin level.
D. Start an exchange transfusion.
E. No action is needed.
ANS:
3.1 E. Administration of phenobarbital induces glucuronyl transferase, thus
reducing neonatal jaundice. Sepsis and acidosis increase the risk of neurologic
damage by increasing the blood-brain barrier’s permeability to bilirubin. Hypoalbuminemia reduces the infant’s ability to transport unconjugated bilirubin to
the liver, and similarly drugs that displace bilirubin from albumin elevate free
levels of unconjugated bilirubin in the serum.
3.2 A. Gilbert syndrome would present with a negative Coombs test, a normal (or
low) hemoglobin, a normal (or slightly elevated) reticulocyte count, and prolonged hyperbilirubinemia. Red cell morphology would be abnormal in DIC
and spherocytosis, polycythemia would present with an elevated hemoglobin
level (that listed above is normal for a newborn), and blood group isoimmunization would present with a positive Coombs test.
3.3 D. Although all infants are relatively deficient in uridine diphosphate glucuronosyltransferase, those with Crigler-Najjar syndrome type I have a severe
deficiency, causing high bilirubin levels and encephalopathy. Treatment is phototherapy. Encephalopathy is rare with Crigler-Najjar syndrome type II, in
which bilirubin levels rarely exceed 20 mg/dL.
3.4 B. Although the etiology of the hyperbilirubinemia must be investigated, phototherapy should be started.