An infant with severe jaundice that is not corrected by phototherapy is in danger of developing kernicterus. This can occur in infants with Crigler–Najjar syndrome, a genetic disorder in which there is a near-complete deficiency of glucuronyl transferase.
Which of the following laboratory findings would be expected in blood tests in an infant with Crigler–Najjar syndrome?
A. Decreased hematocrit B. Decreased indirect bilirubin C. Increased direct bilirubin D. Increased indirect bilirubin E. Increased reticulocyte count
Increased indirect bilirubin-the correct answer is d. in criglernajjar syndrome, the absence of glucuronyl trans ferase results in an inability to conjugate bilirubin, leading to an unconjugated hyperbilirubinemia (high indirect bilirubin). the jaundice will become more severe as bilirubin accumulates, and at high levels will result in brain damage. two entities have been identifi ed: type 1 (autosomal recessive) and type 2 (autosomal dominant). a partial glucuronyl transferase defi - ciency is found in gilberts syndromeanswer a is incorrect. while the patient may have abnormalities in hematocrit, they would not be due to a glucuronyl transferase defi - ciencyanswer b is incorrect. if an enzyme for conjugation is lacking, unconjugated (indirect) bilirubin will increase, not decreaseanswer c is incorrect. because the enzyme missing is used for conjugating bilirubin, direct bilirubin will decrease, not increaseanswer e is incorrect. a hemolytic anemia would cause an increased reticulocyte count and also increase bilirubin level, which would result in jaundice. while this would further complicate the infants condition, hemolytic anemia is not the cause of criglernajjar syndrome, nor is it associated with that syndrome.