CASE REPORT Journal of the College of Physicians and Surgeons Pakistan 2020, Vol. 30(06): 655-658 655 Late Diagnosis of Paracetamol Poisoning is Always Lethal in Young Adult Sehrish Naz, Safia Fatima and Muhammad Aamir Department of Chemical Pathology and Endocrinology, AFIP, National University of Medical Sciences, Rawalpindi, Pakistan ABSTRACT Acetaminophen has a remarkable safety profile when prescribed in proper therapeutic doses, but hepatotoxicity can occur when misused or after an overdose. The principal toxic metabolite of acetaminophen is N-acetyl-p-benzoquinone imine (NAPQI). Toxicity should be considered in all suspicious cases because of the ubiquitous and initially asymptomatic nature of acetaminophen intoxication. A case of 29-year male soldier is discussed, who presented with pain in abdomen, vomiting and jaundice of sudden onset. The diagnosis of ischemic liver damage was made at initial presentation. Raised liver function tests and elevated prothrombin time were the first indication to this condition, which were proven by detection of acetaminophen in blood and urine by liquid chromatography-mass spectrometry. Further supportive evidence of hepatic necrosis was provided by an ultrasound abdomen, giving the final diagnosis of acetaminophen poisoning causing drug-induced liver injury. Key Words: Acetaminophen poisoning, Drug-induced liver injury, Fulminant hepatic failure, N-acetylcysteine, N-acetyl-p-benzoqui- none imine (NAPQI). How to cite this article: Naz S, Fatima S, Aamir M. Late Diagnosis of Paracetamol Poisoning is Always Lethal in Young Adult. J Coll Physicians Surg Pak 2020; 30(06):655-658 https://doi.org/10.29271/jcpsp.2020.06.655. INTRODUCTION According to USA documented data, acetaminophen or N- acetyl-para-aminophenol (APAP), commonly sold as parace- tamol, is the most widely used analgesic and antipyretic. The dose of up to 4000 mg per 24 hours of acetaminophen is safe as advertised by the US Food & Drug Administration (FDA) and does not produce toxic effects. If the dose exceeds above 150 mg/kg as a single dose, toxic effects are produced resulting in liver failure. About 90 percent of the APAP is channeled into phase II metabolic pathway and converted to glucouronidated andsulfatedmetabolites,whichareeliminatedfromthebodyin the urine. 1 Almost 10 percent of the APAP is shunted by cytochrome (CYP) 2E1 to phase I oxidation, resulting in forma- tion of a highly reactive toxic metabolite, known as, N-acetyl- para-benzo-quinone imine (NAPQI). 2 A very small amount, i.e., almost two percent of APAP is excreted unchanged in the urine. Hepatotoxicity induced by acetaminophen overdose occurs through production of the harmful NAPQI metabolite. When present in excessive quantities, it results in depletion of glutathione, oxidative stress and mitochondrial dysfunction leading to depletion in adenosine triphosphate (ATP) stores. Correspondence to: Dr. Sehrish Naz, Department of Chemical Pathology and Endocrinology, AFIP, National University of Medical Sciences, Rawalpindi, Pakistan E-mail: sehrishnaz007@gmail.com ..................................................... Received: July 16, 2019; Revised: August 31, 2019; Accepted: September 02, 2019 DOI: https://doi.org/10.29271/jcpsp.2020.06.655 Correct initial diagnosis of paracetamol overdose is critical. Timely identification and early therapy may prevent significant morbidity and mortality. Four established sequential stages of paracetamol-induced hepatotoxicityshouldbeconsidereduponpresentationtoclinic (Table I). Table I: Stages of paracetamol-induced hepatotoxicity. Stage Time post ingestion Description Recovery phase First 24 hours Nonspecific symptoms like anorexia, nausea, vomiting. 24 - 72 hours Right upper quadrant abdominal pain (common). In severe poisoning, AST, ALT bilirubin and PT (usually reported as the INR) elevated. Persistant Vomiting with symptoms of liver failure. 72 – 96 hours Peaking of serum ALT, AST, bilirubin, and INR. After 96 hours Resolution of hepatotoxicity or progression to multiple organ failure. Rumack-Matthew nomogram is a widely acceptable tool used in the management of acetaminophen overdose. 3 It is applicable onlyintheeventofsingleacuteingestionoriftheacuityofinges- tionisknowntobewithin24hours.Acetaminophen-inducedliver injury is known to raise serum aminotransferases above 10,000 IU/L. 4 New biomarkers available are acetaminophen / cysteine protein adducts which indicate exposure to acetaminophen. 5