What are the prognostic indicators in acetaminophen toxicity/poisoning?

Updated: Jan 17, 2020
  • Author: Susan E Farrell, MD; Chief Editor: Michael A Miller, MD  more...
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A number of screening measurements have been studied as prognostic indicators after acetaminophen ingestion. The most widely used predictors are the King’s College Criteria, which have been well-validated to predict poor outcome and need for liver transplantation after an isolated acetaminophen overdose. The criteria consist of the following laboratory abnormalities; any serological or clinical finding should prompt urgent transplantation consultation:

  • Arterial pH less than 7.30 after fluid resuscitation

  • Creatinine level greater than 3.4 mg/dL

  • Prothrombin time (PT) greater than 1.8 times control or greater than 100 seconds, or International Normalized Ratio (INR) greater than 6.5

  • Grade III or IV encephalopathy

Levine et al reported that the combination of hypoglycemia, coagulopathy, and lactic acidosis performed better than the King's College criteria for predicting death or transplant. In their retrospective cohort study of 334 adult patients with a discharge diagnosis of acetaminophen-induced liver failure, the presence of hypoglycemia increased the odds of reaching the composite endpoint (death or transplantation) by 3.39-fold. For the combination of hypoglycemia, coagulopathy, and lactic acidosis, the pseudo R2 for the area under the curve was 0.93, versus 0.20 for the King's College criteria. [21]

Another prognostic screening tool that has been studied in regard to predicting the need for liver transplantation is the Acute Physiology and Chronic Health Evaluation II (APACHE II) score completed on the patient’s first inpatient hospital stay. In one study, the APACHE II score was found to be accurate, but cumbersome to apply. [22]

Additional early predictors include changes in serum phosphate levels, which indirectly represent the balance between the development of renal failure and hepatic regeneration. Serum phosphate concentrations greater than 1.2 mmol/L measured at 48-96 hours after overdose were sensitive and specific for increased mortality. [23]

Finally, elevations in blood lactate levels have been studied as prognostic indicators after acute acetaminophen overdose. [24] Blood lactate levels greater than 3.5 mmol/L before fluid resuscitation or greater than 3 mmol/L after fluid resuscitation were found to be sensitive and specific indicators of survival. When compared to the King’s College Criteria, there was no significant time difference to clearly identify patients who required transplantation.

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