Cholinesterase Phenotyping

Pathology category

Biochemistry - referred tests

Code

CHS

Referral code

Request form

Test information

Succinyldicholine (suxamethonium), a muscle relaxant used during surgery, is hydrolysed by cholinesterase; its pharmacological effect usually lasts only long enough to meet the needs of the surgical procedure. However, in patients with low total activity, or a weakly active variant, the breakdown of the drug will not occur rapidly enough and the patient may enter a period of prolonged apnoea, which requires mechanical ventilation.

Guidelines

Pre-analytical

If collecting samples after an episode of prolonged apnoea please wait at least 48 hours after surgery

Reference range

Total activity: 650 – 1450 U/L

Tube type

Tube type info

EDTA plasma

Special requirements

EDTA plasma 0.5 ml (min volume 150 ul) – Sent first class post to Cardiff toxicology lab

Minimum volume

500 uL

Assay frequency

TAT Inpatient (urgent)

TAT Inpatient

4 weeks

TAT GP/Outpatient

4 weeks

Referral lab

Department of Toxicology, Llandough Hospital