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- Dibucaine Inhibition
Test Includes
Dibucaine percent inhibition only
Expected Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum or plasma
Volume
0.5 mL
Minimum Volume
0.2 mL
Container
Red-top tube, gel-barrier tube, or lavender-top (EDTA) tube
Collection
Separate serum or plasma from cells and place in transport tube. Mark transport tube appropriately “serum” or “plasma.”
Storage Instructions
Room temperature
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Patient Preparation
Do not collect within 24 hours of administration of muscle relaxant.
Causes for Rejection
Plasma or serum not separated from cells; frozen whole blood received; hemolysis
Test Details
Use
Assess the presence of homozygous or heterozygous “atypical” cholinesterase variant, in patients who have low result of serum or plasma cholinesterase assay, and may be at risk of apnea when given succinylcholine muscle relaxant
Limitations
No single simple test currently exists that can detect all enzyme variants.
This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
Methodology
Cholinesterase by spectrophotometry (Ellman) with dibucaine inhibition
Reference Interval
Normal: 70% to 90% inhibition; heterozygotes: 30% to 70% inhibition; homozygotes: 0% to 30% inhibition
Additional Information
The degree of serum or plasma cholinesterase inhibition produced by dibucaine is under genetic control. Sensitivity to succinyl choline is dependent upon at least four allelic genes. The total quantitative cholinesterase determination may not be reliable in detecting sensitivity to succinyl choline as variant enzymes exhibit qualitative and quantitative differences in substrate specificity.
The dibucaine number indicates the percent inhibition of enzyme activity by this agent when a serum or plasma sample is tested under standard conditions (inhibition expressed as a percent). This approach to detection of serum or plasma cholinesterase variants does not entirely avoid the problem of variation in reactivity with some atypical enzymes. Prolonged apnea following hemodilutional cardiopulmonary bypass has been reported in a patient whose admission (preoperative) plasma cholinesterase level was slightly below the normal range.1
Footnotes
1. Jackson SH, Bailey GW, Stevens G. Reduced plasma cholinesterase following haemodilutional cardiopulmonary bypass. Anaesthesia. 1982 Mar; 37(3):319-321. 7091605
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 081513 | Dibucaine Number | 39354-6 | 081513 | Dibucaine Number | % inhibition | 39354-6 |
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