Hemolysis and hemolytic uremic syndrome following five-fold N-acetylcysteine overdose

Intravenous acetylcysteine (Acetadote™ in the US) is the treatment of choice for acute acetaminophen poisoning in most of the world. However, the complicated dosing regimen is prone to errors in preparation and administration.

A 21 year-old woman (70 kg) took an overdose of acetaminophen and ethanol. Her serum acetaminophen concentration was > 200 mg/L. Acetylcysteine infusion was ordered. Due to misreading of the columns in the table in the Acetadote™ package insert, she received a five-fold overdose of 52.5 g of acetylcysteine in 500 mL over 1 h and then 17.5 g of acetylcysteine in 500 mL to run over 4 h. The dose error was detected 20 min into the second infusion. Her acetaminophen concentration fell quickly, and her highest transaminase concentrations occurred day 2. Her hemoglobin and hematocrit quickly dropped from 14.8 g/dL and 44.0% on admission to 6.2 g/dL and 17.3% on day 7. Subsequently she developed hematuria and a rapidly rising serum creatinine. She was transferred to a tertiary care hospital, where she underwent hemodialysis every two days for two weeks, transfusions of packed red blood cells, and plasmapheresis until hematologic testing ruled out thrombotic thrombocytopenia purpura.

A five-fold overdose of acetylcysteine was followed by unexpected hemolysis and acute renal failure. The mechanism of hemolysis after acetylcysteine overdose is unclear. A simpler infusion regimen with standard concentrations would prevent a similar error.