Cholinesterase

The department provides specialist analysis of the enzyme butyrylcholinesterase, BChE (also referred to as serum cholinesterase), with enzyme activity, biochemical phenotyping and genotyping investigations available.

BChE is an enzyme responsible for the metabolism of the muscle relaxants suxamethonium (scoline) and mivacurium that shows a great deal of genetic variation. Some variants lead to an effective enzyme deficiency which impairs an individual’s ability to metabolise the drugs and leads to prolonged paralysis and apnoea.

Biochemical phenotypes of BChE are identified by inhibitor studies with agents such as dibucaine and fluoride. All reports are issued with interpretative comments and an assessment of risk (of suxamethonium sensitivity) based on the phenotype and enzyme activity. Warning cards are issued for patients likely to be sensitive to suxamethonium and recommendations given with the report on the need for family studies.

Where more detailed information is required DNA studies are often of value and can, on request, be carried out on the same sample (EDTA whole blood).  Analysis is now performed by Bristol Genetics Laboratory using DNA sequencing, covering the full coding region of the BCHE gene. Results are reported alongside the biochemistry results with a full interpretation.

Serum cholinesterase activity can also be performed for occupational monitoring in workers handling organophosphate pesticides.  An initial baseline sample should be taken prior to any exposure to determine the individual’s baseline activity.