A neonate born at 34 weeks receives chloramphenicol for an infection. Two days later she becomes gray, hypothermic, hypotonic and develops vomiting with cardiovascular collapse. The underlying cause of this presentation is:
- A Displacement of bilirubin from albumin causing kernicterus
- B Deficient renal tubular secretion causing toxic levels of the inactive metabolite
- C Immature hepatic glucuronidation leading to accumulation of unconjugated chloramphenicol ✓
- D Idiosyncratic bone marrow suppression from a genetic hypersensitivity reaction
Correct answer: C. Immature hepatic glucuronidation leading to accumulation of unconjugated chloramphenicol
Explanation
Gray baby syndrome results from inadequate hepatic UDP-glucuronosyltransferase activity in newborns, especially preterm infants, so unmetabolized chloramphenicol accumulates and blocks mitochondrial electron transport in myocardial cells, producing circulatory collapse, vomiting, flaccidity, hypothermia and ash-gray skin color. Idiosyncratic aplastic anemia is a separate late complication seen weeks after exposure and is unrelated to age. Displacement of bilirubin occurs but does not produce this acute cardiovascular picture.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.