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PTD - 204

Test Directory - Cholinesterase (Serum)


Pseudocholinesterase, scoline sensitivity, butyrylcholinesterase.

Clinical Indications

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.

Test Includes

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

Request Form

Combined Pathology Blood form (Yellow/Black)


Analysed by Clinical Biochemistry, Lewisham Hospital 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

4 Weeks




2 ml


Yellow top (SST) tube

Causes for Rejection

Not meeting specific criteria for analysis.

Reference Range

Total Cholinesterase: 600 - 1,400 IU/L.
Dibucaine number 76 - 83, fluoride number 56 - 66, R02 number 93 - 98.
Scoline-sensitive phenotypes are AA, AK, and KK. Normal phenotype is UU. Heterozygotes are not usually sensitive but scoline sensitivity may increase during pregnancy, and total levels may also be reduced.


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.

Lab. Handling

Processing: Aliquot and store at 4C in separating fridge (CB39).
: TC and send or BPRO and save at -20C in separating freezer (CB40)

Version 1.0 / April 2014                                                                                                          Approved by: Consultant Biochemist