Pathology Handbook

Cholinesterase

Synonyms

Pseudocholinesterase, scoline sensitivity, butyrylcholinesterase.

Clinical Indications

To confirm the diagnosis of Anectine (suxamethonium chloride) and mivacron (Mivacurium) apnoea after anaesthetic.

To determine phenotype of patients with low serum Cholinesterase activities

Patients with an abnormal phenotype should have family studies performed, and if sensitive to Scoline should be issued with a sensitivity card

Patients with ?organophosphorus poisoning can also have serum levels measured but red cell acetylcholinesterase can also be measured

Susceptibility to 'Scoline apnoea' is inherited as an autosomal dominant disorder; cholinesterase activity is usually, but not always, low. Dibucaine and fluoride numbers improve the sensitivity and specificity of the test.
Family studies should be done on patients found to be sensitive so that other affected individuals can be cautioned against exposure to suxamethonium or mivacurium.

For further useful information about cholinesterase follow this link

Test Includes

Total cholinesterase, dibucaine, fluoride and RO numbers, phenotype.

Request Form

Request on ICE

Availability

Analysed by referral laboratory if specific criteria met.

Specific Criteria

Investigation of suspected scoline sensitivity, prolonged apnoea following suxamethonium (Scoline) or mivacurium. Part of family studies.

Patient Preparation 

Do not take samples during apnoea or within 24 hours of suxamethonium administration. If FFP or cholinesterase preparations have been given, then wait 6 weeks before taking sample.

Turnaround Time

3 weeks

Specimen

SST Serum AND Biochemistry EDTA sample

Volume

5 ml

Container

Vacutainer gold top

Vacutainer lemon top

Lab Handling

Sent to referral laboratory

Causes for Rejection

Unlabelled or incorrectly labelled sample; not meeting specific criteria for analysis; inadequate clinical information.

Reference Range

Total Cholinesterase: 3,700 - 11,500 IU/L.

Normal phenotype is UU.
Scoline-sensitive phenotypes are AA, AK, and KK. 

Heterozygotes are not usually sensitive but scoline sensitivity may increase during pregnancy, and total levels may also be reduced.

For sensitive individuals a sensitivity card should be enclosed with the result. This is sent to the clinician concerned together with a covering letter

Interpretation

Low levels are also found in pregnancy and in patients with hepatocellular disease. Organophosphate poisoning reduces the activity of this enzyme, making it useful for the detection of poisoning. Red cell cholinesterase may also be required for the diagnosis of poisoning with organophosphate or carbamate insecticides and monitoring of long term exposure.