Crigler-Najjar syndrome
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Flashcards
Crigler-Najjar syndrome
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Questions
USMLE® Step 1 style questions USMLE
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A 5-month-old female is brought to the pediatrician for evaluation of jaundice that began after a viral upper respiratory tract infection. She was born at 39 weeks gestation to a 27-year-old, gravida 1 para 1, woman via spontaneous vaginal delivery. The patient has been meeting developmental milestones. Family history is noncontributory. Physical examination shows scleral icterus and diffuse jaundice. Abdominal and neurological exams are unremarkable. Blood testing is performed and reveals the following:
Phenobarbital is administered, and repeat total serum bilirubin is measured at 7 mg/dL. Which of the following best describes the cause of this patient’s condition?
| Laboratory value | Result |
| Hemoglobin | 13.9 mg.dL |
| Leukocyte count | 6,800/mm3 |
| Total bilirubin | 12.7 mg/dL |
| Conjugated bilirubin | 0.3 mg/dL |
| Alanine aminotransferase | 15 U/L |
| Aspartate aminotransferase | 16 U/L |
External References
First Aid
2024
2023
2022
2021
Crigler-Najjar syndrome p. 400, 401
presentation p. 724
Jaundice p. 400
Crigler-Najjar syndrome p. 724
Summary
Crigler-Najjar syndrome is an inherited disorder that affects the ability to break down bilirubin, a pigment produced when red blood cells are broken down. Crigler-Najjar syndrome is caused by the absence (type I) or reduced activity (type II) of the enzyme UDP-glucuronosyltransferase, and people having this disease present with high levels of bilirubin in their blood, which can cause yellowing of the skin and eyes (jaundice), dark urine, lightheadedness, confusion, and coma. The severity of symptoms varies among people with this condition.