An Immunoassay to Rapidly Measure Acetaminophen Protein Adducts Accurately Identifies Patients With Acute Liver Injury or Failure

Abstract

Background & Aims A rapid, reliable point-of-care assay to detect acetaminophen protein adducts in serum of patients with acute liver injury could improve diagnosis and management. AcetaSTAT is a competitive immunoassay used to measure acetaminophen protein adducts formed by toxic metabolites in serum samples from patients. We compared the accuracy of AcetaSTAT vs high-pressure liquid chromatography with electrochemical detection (HPLC-EC, a sensitive and specific quantitative analytical assay) to detect acetaminophen protein adducts. Methods We collected serum samples from 19 healthy individuals (no liver injury, no recent acetaminophen use), 29 patients without acetaminophen-associated acute liver injury, and 33 patients with acetaminophen-associated acute liver injury participating in the Acute Liver Failure Study Group registry. Each serum sample was analyzed by AcetaSTAT (reported as test band amplitude) and HPLC-EC (the reference standard). We also collected data on patient age, sex, weight, level of alanine aminotransferase on test day and peak values, concentration of acetaminophen, diagnoses (by site investigator and causality review committee), and outcome after 21 days. Differences between groups were analyzed using Fisher’s Exact for categorical variables and Kruskal-Wallis Test or Rank-Sum test for continuous variables. Results AcetaSTAT discriminated between patients with and without acetaminophen-associated acute liver injury; the median (and range) AcetaSTAT test band amplitude for patients with acetaminophen-associated acute liver injury was 584 (range, 222–1027) vs 3678 (range, 394–8289) for those without (P<.001). AcetaSTAT identified patients with acetaminophen-associated acute liver injury with 100% sensitivity, 86.2% specificity, a positive-predictive value of 89.2%, and a negative-predictive value of 100%. Results from AcetaSTAT were positive in 4 subjects who received a causality review committee diagnosis of non-acetaminophen–associated acute liver injury; HPLC-EC and biochemical profiles were consistent with acetaminophen-associated acute liver injury in 3 of these cases. Conclusion The competitive immunoassay AcetaSTAT demonstrates a high degree of concordance with HPLC-EC results in identifying patients with acetaminophen-associated acute liver injury. This rapid and simple assay could increase early detection of this disorder and aid clinical management.

Multiple admissions for acetaminophen overdose: Acetaminophen frequent fliers, a new entity?

“…During his first admission, he denied APAP; and the drug had been fully metabolized, giving the undetectable level that initially confused his care team . In future, assays that detect APAP adducts, the toxic by‐product, should allow for rapid point‐of‐care diagnosis of APAP toxicity to decrease delay (or failure) to begin NAC when patients deny using APAP …”

“…(3) In future, assays that detect APAP adducts, the toxic by-product, should allow for rapid point-of-care diagnosis of APAP toxicity to decrease delay (or failure) to begin NAC when patients deny using APAP. (4) The current opioid abuse crisis features high rates of both overdose-related mortality and escalation to heroin and fentanyl abuse. Our patients highlight an underappreciated aspect of this epidemic, the associated APAP toxicity and need for NAC use in this setting regardless of severity of liver injury.…”

Herbal Therapy for the Treatment of Acetaminophen-Associated Liver Injury: Recent Advances and Future Perspectives

“…However, these molecules are also identified in the majority of subjects taking a therapeutic dose of APAP, and protein-derived APAP-cysteine is detectable after supratherapeutic consumption of APAP without hepatotoxicity (O'Malley et al, 2015). Recently, Roberts et al (2017) differentiated ALI from the others using APAP protein adducts by developing an immunoassay that rapidly measures APAP protein adducts to identify ALF. Therefore, considering the presence of APAP protein adducts at the therapeutic dose of APAP, formation of protein adducts on mitochondrial proteins rather than the overall formation of protein adducts may be the reason for cellular toxicity, which has been considered a key factor for necrotic cell death in previous years (Jollow et al, 1973;Hu et al, 2016).…”

Acetaminophen Toxicity: Novel Insights Into Mechanisms and Future Perspectives

“…However, protein adducts are also detectable in the vast majority of subjects taking therapeutic doses of APAP 12 and protein-derived APAP-cysteine can be detected after repeated supra-therapeutic ingestion of APAP in the absence of hepatotoxicity 13 . While the clinical utility of APAP-protein adduct measurements in this context have been questioned 14 , a recently developed competitive immunoassay (AcetaSTAT) has been suggested to identify patients with APAP-induced acute liver injury or failure 15 . Due to these clinical implications, a better understanding of protein adducts formation and its relationship to hepatocyte necrosis is warranted.…”