Background Despite extensive investigation, the cause of liver injury in 14% of acute liver failure patients remains unknown (indeterminate). In a pilot study, using a novel assay, highly specific acetaminophen-cysteine adducts were detected in 7 of 36 (19%) indeterminate patients. Methods To extend these observations, sera from 110 subjects enrolled in the Acute Liver Failure Study Group registry with indeterminate acute liver failure were analyzed using a similar but more efficient and sensitive adduct assay. As positive controls, an additional 199 patients with known or presumed acetaminophen-induced liver failure were assessed for the presence and quantity of adducts. Clinical, laboratory and outcome data were compared for the two groups. Results Based on previous data from known therapeutic exposures and acetaminophen overdoses, an adduct concentration of ≥1.0 nmol/mL serum indicated a definite acetaminophen overdose. Among the 110 indeterminate cases, 18% had assay values ≥1.0, with a median level of 9.2 nmol/mL; 94.5 % of the positive control (known APAP) cases had values ≥1.0 nmol/mL. Regardless of initial diagnosis, subjects with elevated adduct levels demonstrated the clinical profile and hyperacute biochemical injury pattern associated with acetaminophen overdose: predominance of female gender, very high aminotransferase levels and low bilirubin levels. Conclusions These data confirm and extend previous observations regarding the high (18%) prevalence of unrecognized or uncertain acetaminophen toxicity among subjects with indeterminate acute liver failure. N-acetylcysteine use was limited in this group, presumably because of the lack of a specific diagnosis of acetaminophen toxicity.

Isoniazid (INH)-induced hepatotoxicity remains one of the most common causes of drug-induced idiosyncratic liver injury and liver failure. This form of liver injury is not believed to be immune-mediated because it is not usually associated with fever or rash, does not recur more rapidly on rechallenge, and previous studies have failed to identify anti-INH antibodies. In this paper we found antibodies present in the sera of 15/19 cases of INH-induced liver failure. Anti-INH antibodies were present in 8; 11 sera had anti-CYP2E1 antibodies, 14 sera had antibodies against CYP2E1 modified by INH, 14 sera had anti-CYP3A4 antibodies, and 10 sera had anti-CYP2C9 antibodies. INH was found to form covalent adducts with CYP2E1, CYP3A4, and CYP2C9. None of these antibodies were detected in sera from INH-treated controls without significant liver injury. The presence of a range of anti-drug and autoantibodies has been observed in other drug-induced liver injury that is presumed to be immune-mediated. Conclusion These data provide strong evidence that INH induces an immune response that causes INH-induced liver injury.

BACKGROUND & AIMS Patients with acute liver failure (ALF) frequently develop renal dysfunction, yet its overall incidence and outcomes have not been fully assessed. We investigated the incidence of acute kidney injury (AKI) among patients with ALF, using defined criteria to identify risk factors and to evaluate its effect on overall outcomes. METHODS We performed a retrospective review of data from 1604 patients enrolled in the Acute Liver Failure Study Group, from 1998 through 2010. Patients were classified by the Acute Kidney Injury Network criteria, as well as for etiology of liver failure (acetaminophen-based, ischemic, and all others). RESULTS Seventy percent of patients with ALF developed AKI, and 30% received renal replacement therapy (RRT). Patients with severe AKI had higher international normalized ratio values than those without renal dysfunction (P < .001), and a higher proportion had advanced-grade coma (coma grades 3 or 4; P < .001) or presented with hypotension requiring vasopressor therapy (P < .001). A greater proportion of patients with acetaminophen-induced ALF had severe kidney injury than of patients with other etiologies of ALF; 34% required RRT, compared with 25% of patients with ALF not associated with acetaminophen or ischemia (P < .002). Of the patients with ALF who were alive at 3 weeks after study entry, significantly fewer with AKI survived for 1 year. Although AKI reduced the overall survival time, more than 50% of patients with acetaminophen-associated or ischemic ALF survived without liver transplantation (even with RRT), compared with 19% of patients with ALF attribute to other causes (P < .001). Only 4% of patients requiring RRT became dependent on dialysis. CONCLUSIONS Based on a retrospective analysis of data from more than 1600 patients, AKI is common in patients with ALF and affects short- and long-term outcomes, but rarely results in chronic kidney disease. Acetaminophen-induced kidney injury is frequent, but patients have better outcomes than those with other forms of ALF.

Viral metagenomic surveillance of 187 patients with indeterminate acute liver failure (ALF) from 1998 to 2010 suggests that these patients should be screened for the presence of uncommon viruses and coinfections, although novel viruses associated with ALF were not identified.

Background Hepatitis B virus-related acute liver failure (HBV-ALF) may occur following acute HBV infection (AHBV-ALF) or during an exacerbation of chronic HBV infection (CHBV-ALF). Clinical differentiation of the two is often difficult if a prior history of hepatitis B is not available. Quantitative measurements of anti-hepatitis B core immunoglobulin M (IgM anti-HBc) titers and of HBV viral loads (VLs) might allow separation of acute from chronic HBV-ALF. Methods Of 1602 patients with ALF, 60 met clinical criteria for AHBV-ALF and 27 for CHBV-ALF. Sera were available on 47 and 23 patients, respectively. A quantitative immunoassay was used to determine IgM anti-HBc levels, and real-time polymerase chain reaction (rtPCR) to determine HBV VLs. Results AHBV-ALFs had much higher IgM anti-HBc titers than CHBV-ALFs, (signal to noise (S/N) ratio median 88.5, range 0–1,120, vs. 1.3, 0–750, p<0.001); a cut point for S/N ratio of 5.0 correctly identified 44/46 (96%) AHBV-ALFs and 16/23 (70%) CHBV-ALFs; the area under the receiver operator characteristic curve was 0.86, p<0.001. AHBV-ALF median admission VL was 3.9 (0–8.1) log10 IU/mL, vs. 5.2 (2.0–8.7) log10 IU/mL for CHBV-ALF, p<0.025. Twenty percent (12/60) of the AHBV-ALF group had no hepatitis B surface antigen (HBsAg) detectable on admission to study, while no CHBV-ALF patients experienced HBsAg clearance. Rates of transplant-free survival were 33% (20/60) for AHBV-ALF vs. 11% (3/27) for CHBV-ALF, p=0.030. Conclusions AHBV-ALF and CHBV-ALF differ markedly in IgM anti-HBc titers, in HBV VLs and in prognosis, suggesting that the two forms are indeed different entities that might each have a unique pathogenesis.