Pseudocholinesterase, Dibucaine Inhibition
0020159
Ordering Recommendation
Order to detect increased sensitivity in individuals who experience prolonged paralysis following succinylcholine or mivacurium administration.
Submit With Order
Mnemonic
PCHE PHENO
Methodology
Quantitative Enzymatic
Performed
Mon-Fri
Reported
1-5 days
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Specimen must be drawn prior to surgery or more than two days following surgery. Do not draw in recovery room.  
Collect
Serum separator tube, green (sodium or lithium heparin), lavender (EDTA), or pink (K2EDTA).  
Specimen Preparation
Allow specimen to clot completely at room temperature. Separate serum or plasma from cells ASAP or within 2 hours of collection. Transport 1 mL serum or plasma. (Min: 0.25 mL)  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
Lt. blue (sodium citrate) or gray (oxalate/fluoride). Whole blood.  
Remarks
 
Stability
Ambient: 4 hours; Refrigerated: 1 week; Frozen: 3 months  
Reference Interval
Test Number Components Reference Interval
Phenotype By report
0020167Pseudocholinesterase, Total 2,900-​7,100 U/L
Interpretive Data
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 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 be 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.

See Compliance Statement B: www.aruplab.com/CS
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 to prolonged paralysis 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 to prolonged paralysis 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 "U" 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 to prolonged paralysis 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 to prolonged paralysis with large dose and short surgery.

Patients with acute or chronic liver disease, organophosphate poisoning, chronic renal disease, in late stages of pregnancy, or on estrogen therapy may have markedly decreased PChE activities.
CPT Code(s)
82638; 82480
Components
Component Test Code*Component Chart Name
0020059Pseudocholinesterase, Total
0020060Dibucaine Number
0020157PChE Presumptive Phenotype
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Cross References
  • Butyrylcholinesterase
  • Cholinesterase
  • Cholinesterase, Serum
  • Dibucaine
  • Dibucaine Inhibition
  • Dibucaine Number
  • Serum Cholinesterase
  • Serum Pseudocholinesterase