Newborn with Lethargy, Jaundice, and Coagulopathy

Laboratory results include the following: white blood cell count, 21,600/μL (21.6 × 109/L; reference range, 9,000-30,000/μL [9-30 × 109/L]); hemoglobin, 18.2 g/dL (182 g/L; reference range, 14.0-24.0 g/dL [140-240 g/L]); platelet count, 111 × 103/μL (111 × 109/L; reference range, 150-450 × 103/μL [150-450 × 109/L]); blood type, B+; direct antiglobulin test, negative; and reticulocyte count, 4% (reference range, 3%-7%). Comprehensive metabolic panel is significant for hyponatremia, with a sodium level of 132 mEq/L (132 mmol/L; reference range, 135-145 mEq/L [135-145 mmol/L]). Liver enzyme levels are normal (alanine aminotransferase, 41 U/L [0.68 μkat/L]; aspartate aminotransferase, 86 U/L [1.44 μkat/L]), as are total protein (5.4 g/dL [54 g/L]) and albumin (3.0 g/dL [30 g/L]) levels. Repeated bilirubin level is 12.4 mg/dL (212 µmol/L) at 14 hours after birth, with an elevated direct bilirubin level of 2.9 mg/dL (49.6 µmol/L). Direct or conjugated hyperbilirubinemia is defined as a direct bilirubin level greater than 2 mg/dL (34.2 mmol/L) or more than 20% of total bilirubin. γ-Glutamyl transferase level is normal. Coagulation studies show an elevated prothrombin time of 23.4 seconds (reference range, 11-17 seconds), with an international normalized ratio of 2.1 (reference range, 0.9-1.3); activated partial thromboplastin level is 49.5 seconds (reference range, 30-60 seconds). Fibrinogen level is decreased at 70 mg/dL (0.70 g/L) (reference range, 230-450 mg/dL [230-450 g/L]). Lactate level is 24.3 mg/dL (2.7 mmol/L; reference range, 2.0-26.9 mg/dL [0.22-2.98 mmol/L]). Ammonia level is 96.6 µg/dL (69 μmol/L; reference range, 89.6-149.9 µg/dL [64-107 μmol/L]). Cerebrospinal fluid studies are unremarkable. Magnetic resonance imaging (MRI) of the brain and echocardiography are normal. Ultrasonography of the abdomen shows diffuse hepatic echogenicity. Blood and cerebrospinal fluid cultures are negative. Further testing reveals the diagnosis.