A Newborn with Hypothermia and Hyperammonemia

Hyperammonemia, a nonspecific marker of inadequate nitrogen detoxification, is the biochemical hallmark ofmostUCDs; therefore, a plasma ammonia concentration is the first laboratory test indicated for the workup of a UCD. Diagnosis of CTLN1 is based on clinical suspicion and laboratory evaluation (plasma ammonia >150 ^.mol/L, plasma citrulline >1000 ^.mol/L, and absence of arginosuccinic acid in the amino acid profile). Author Contributions: All authors confirmed they have contributed to the intellectual content ofthispaper and have met the following 3 requirements: (a) significant contribution to the conception and design, acquisition ofdata, oranalysis and interpretation ofdata; (b) draftingorrevisingthe article for intellectual content; and (c) final approval ofthe published article.