N-acetylcysteine (NAC) was found to improve transplantation-free survival in only those adults with non-acetaminophen (non-APAP) acute liver failure (ALF) and grade 1–2 hepatic encephalopathy (HE). Because non-APAP ALF differs significantly between children and adults, the Pediatric Acute Liver Failure (PALF) Study Group evaluated NAC in non-APAP PALF. Children from birth through age 17 years with non-APAP ALF enrolled in the PALF registry were eligible to enter an adaptively allocated, doubly masked, placebo-controlled trial using a continuous intravenous infusion of NAC (150 mg/kg/day in 5% dextrose in water [D5W]) or placebo (D5W) for up to 7 days. The primary outcome was 1-year survival. Secondary outcomes included liver transplantation-free survival, liver transplantation (LTx), length of ICU and hospital stays, organ system failure and maximum HE score. A total of 184 participants were enrolled in the trial with 92 in each arm. The 1-year survival did not differ significantly (p=0.19) between the NAC (73%) and placebo (82%) treatment groups. The 1-year LTx-free survival was significantly lower (p=0.03) in those who received NAC (35%) than those who received placebo (53%), particularly, but not significantly so, among those less than 2 years old with HE grade 0–1 (NAC 25%; placebo 60%; p=0.0493). There were no significant differences between treatment arms for hospital or ICU length of stay, organ systems failing, or highest recorded grade of HE. Conclusion NAC did not improve 1-year survival in non-APAP PALF. 1-year LTx-free survival was significantly lower with NAC, particularly among those < 2 years old. These results do not support broad use of NAC in non-APAP PALF and emphasizes the importance of conducting controlled pediatric drug trials, regardless of results in adults.

Objective To describe the frequency of diagnostic testing for the 4 most common causes of pediatric acute liver failure (PALF) (drugs, metabolic disease, autoimmune process, and infections) in indeterminate PALF within the PALF Study Group Database. Study design PALF was defined by severe hepatic dysfunction within 8 weeks of onset of illness, with no known underlying chronic liver disease in patients from birth through 17 years of age. Results Of the 703 patients in the database, 329 (47%) had indeterminate PALF. In this group, a drug history was obtained in 325 (99%) urine toxicology screenings performed in 118 (36%) and acetaminophen level measured in 124 (38%) patients. No testing for common metabolic diseases was done in 179 (54%) patients. Anti-nuclear antibody, anti-smooth muscle antibody, and anti-liver kidney microsomal autoantibodies associated with autoimmunity were determined in 239 (73%), 233 (71%), and 208 (63%) patients, and no tests were obtained in 70 (21%). Testing was performed for hepatitis A virus, hepatitis B virus, and Epstein Barr virus in 80%, 86%, and 68%, respectively. Conclusions Current practice indicates that investigation for metabolic and autoimmune causes of PALF are infrequent in patients ultimately given a diagnosis of indeterminate acute liver failure. This offers an opportunity to improve diagnosis and potential treatment options in children with acute liver failure.

In a multinational study of children with acute liver failure, we found that incorporating diagnostic test recommendations into electronic medical record order sets accessed at time of admission reduced the percentage with an indeterminate diagnosis that may have reduced liver transplants without increasing mortality. Widespread use of this approach could significantly enhance care of acute liver failure in children.

With conventional dietary treatment, the clinical course of methylmalonic acidemia due to cobalamin-unresponsive methylmalonyl-CoA mutase (MCM) deficiency is characterized by the persistent risk of recurrent life-threatening decompensation episodes with metabolic acidosis, hyperammonemia, and coma. Liver transplant has been proposed as an alternative treatment and anecdotally attempted in the last 2 decades with inconsistent results. Most criticisms of this approach have been directed at the continuing risk of neurologic and renal damage after transplant. Here, we report the perioperative and postoperative clinical and biochemical outcomes of 2 patients with severe MCM deficiency who underwent early liver transplant. In both cases, liver transplant allowed prevention of decompensation episodes, normalization of dietary protein intake, and a marked improvement of quality of life. No serious complications have been observed at 12 years' and 2 years' follow-up, respectively, except for mild kidney function impairment in the older patient. On the basis of our experience, we strongly suggest that liver transplant should be offered as a therapeutic option for children with cobalamin-unresponsive MCM deficiency at an early stage of the disease.

Objective Viral infections are often suspected to cause pediatric acute liver failure (PALF) but large-scale studies have not been performed. We analyzed results of viral testing among non-acetaminophen (non APAP) PALF study participants. Methods Participants were enrolled in the PALF registry. Diagnostic evaluation and final diagnosis were determined by the site investigator and methods for viral testing by local standard of care. Viruses were classified as either Causative Viruses (CV) or Associated Viruses (AV). Supplemental testing for CV was performed if not done clinically and serum was available. Final diagnoses included “Viral”, “Indeterminate” and “Other”. Results Of 860 participants, 820 had at least one test result for a CV or AV. A positive viral test was found in 166/820 (20.2%) participants and distributed among “Viral” [66/80 (82.5%)], “Indeterminate” [52/420 (12.4%)] and “Other” [48/320 (15.0%)] diagnoses. CV accounted for 81/166 (48.8%) positive tests. Herpes Simplex Virus (HSV) was positive in 39/335 (11.6%) who were tested: 26/103 (25.2%) and 13/232 (5.6%) among infants 0 - 6 months and over 6 months, respectively. HSV was not tested in 61.0% and 53% of the over-all cohort and those 0 - 6 months, respectively. Supplemental testing yielded 17 positive, including 5 HSV. Conclusions Viral testing in PALF occurs frequently but is often incomplete. Evidence for acute viral infection was found in 20.2% of those tested for viruses. HSV is an important viral cause for PALF in all age groups. The etiopathogenic role of CV and AV in PALF requires further investigation.