Pseudocholinesterase/Dibucaine Inhibition


Sunquest Code:PECHE  
Epic Code:LAB3667Epic Name:PSEUDOCHOL DIBUCAINE
Synonyms:Cholinesterase, Plasma; Acylcholine Acylhydrolase
Methodology:Enzymatic
CPT Code:82638, 82480
Test Includes:Pseudocholinesterase, % Dibucaine Inhibition, and phenotype interpretation.
Turnaround Time:Specimens are sent to reference laboratory Mon-Sat; results are reported in 1-5 days.
Special Instructions:Include clinical information for phenotyping studies.


Collection Instructions

Specimen:Blood
Optimal Volume:2 mL
Minimum\Peds Volume:0.7 mL
Container:Red or gold (gel) (Green (lithium heparin, gel), Green (sodium heparin, no gel), Purple (EDTA), Red (no gel))
Collection Instructions:Collect prior to surgery or 2 days post. Do not collect in recovery room.
Causes for Rejection:Whole blood


Processing and Shipping

Specimen Processing:Centrifuge and aliquot 1 mL, 0.25 mL minimum. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature.
Test Performed at or Referral Lab Lab Sendouts  (ARUP)
Referral Lab number:20159 (PCHE PHENO)


Interpretive

Critical Range:
Reference Range:

PChE: 2900-7100 U/L; Phenotype by report.

Note: Pseudocholinesterase (PChE) Phenotype interpretation is based on the total PChE activity and the percent of inhibition caused by dibucaine. While there are over 25 different phenotypes, most are extremely rare. Patients with unusual phenotypes cannot metabolize succinylcholine or mivacurium in the normal fashion; therefore, these patients can have prolonged paralysis following the use of these drugs. This test can identify the following phenotypes:

 

U

Homozygote Usual (normal), frequency = 96%, indicates this patient will not have prolonged paralysis following the use of succinylcholine or mivacurium.

UA

Heterozygote Usual/Atypical, frequency = 3%, indicates this patient will occasionally have prolonged paralysis following the use of succinylcholine or mivacurium. The patient will be more susceptible with a large dose and short surgery.

A

Homozygote Atypical, frequency 1 in 3,000, indicates this patient will always have prolonged paralysis following the use of succinylcholine or mivacurium.

US

Heterozygote Usual/Silent, frequency = 0.7%, indicates this patient will occasionally have prolonged paralysis following the use of succinylcholine or mivacurium. The patient will be more susceptible with a large dose and short surgery.

S

Homozygote Silent, frequency 1 in 40,000, indicates this patient will always have prolonged paralysis following the use of succinylcholine or mivacurium. This patient could be phenotype ā€œuā€ with concomitant organophosphate poisoning.

AS

Heterozygote Atypical/Silent, frequency 1 in 8,000, indicates this patient will always have prolonged paralysis following the use of succinylcholine or mivacurium.

FS

Heterozygotes Fluoride Sensitive/Silent, frequency rare, indicates that this patient will have prolonged paralysis following the use of succinylcholine or mivacurium. The patient will be more susceptible with large dose and short surgery.

AF

Heterozygote, Atypical/Fluoride Sensitive, frequency rare, indicates that this patient will have prolonged paralysis following the use of succinylcholine or mivacurium. The patient will be more susceptible with large dose and short surgery.

UF

Heterozygotes Usual/Fluoride Sensitive, frequency rare, indicates that this patient may rarely have prolonged paralysis following the use of succinylcholine or mivacurium. The patient will be more susceptible with large dose and short surgery.

 

Patients with acute or chronic liver disease, organophosphate poisoning, chronic renal disease, late stages of pregnancy and estrogen therapy may have markedly decreased PChE activities.

 

Use:

The dibucaine number (DN) is the percent of pseudocholinesterase (PChE) enzyme activity that is inhibited by dibucaine. Together, the DN and the PChE enzyme activity results can help to identify individuals at risk for prolonged paralysis following the administration of succinylcholine. Decreased PChE enzyme activity in conjunction with a DN less than 30 suggests high risk for prolonged paralysis. Normal to decreased PChE enzyme activity in conjunction with a DN of 30-79 suggests variable risk. Although decreased PChE activity in conjunction with DN greater than or equal to 80 suggests variable risk, these results may b e caused by exposure to organophosphates, the presence of liver disease, pregnancy, or circulating succinylcholine. Specimens should be collected 48 hours after the administration of succinylcholine.

 



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