Paracetamol

Background

Paracetamol is a commonly used analgesic which, if taken in excessive amounts, can lead to toxic liver damage. The major metabolites of paracetamol are the glucoronid and sulphate derivatives. A small proportion is metabolised by microsomal oxidation, conjugated to glutathione and subsequently excreted as cysteine or mercapturate conjugates. In the presence of large concentrations of paracetamol, the liver stores of glutathione become depleted. This leads to the oxidised metabolite combining with liver cell components causing hepatic necrosis. This liver cell damage can be reduced by giving the patient thiol group containing compounds such as methionine or N-acetyl cysteine. The need to administer one of these compounds to the patient is assessed by measuring the level of paracetamol in serum between 4 and 12 hours after ingestion.

Reference ranges

Maintenance dose 10 – 30mg/L

Specimen requirements

Sample type:

• Serum or lithium heparin plasma

Sample identification:

• Three patient identifiers from
  • Name
  • D.O.B.
  • Address
  • N.H.S. number
  • Unit Number
  should match on the specimen and request form. This check may be performed prior to centrifugation by the Central Sort department.

Turnaround time

2 hours