Reference Interval:
| Test Number
| Components
| Reference Interval
| | | Phenotype
| By report
| | 0020167 | Pseudocholinesterase, Total
| 2,900-7,100 U/L
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| 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.
Refer to Statement B under Testing information at http://www.aruplab.com.
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| 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.
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| CPT Code(s): |
82638; 82480
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Cross References: |
Cholinesterase, Serum (Pseudocholinesterase, Dibucaine Inhibition), Dibucaine (Pseudocholinesterase, Dibucaine Inhibition) |
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