Cholinesterase, RBC and Plasma [338]

For Specimen Integrity during Extreme Weather see the “Lockbox Usage in Extreme Weather” document at the top of this page.

Test Code

Alias/See Also

CPT Codes
82480, 82482

Preferred Specimen
5 mL whole blood collected in an EDTA (lavender-top) and
1 mL plasma collected in an EDTA (lavender-top)

Minimum Volume
4 mL whole blood • 0.5 mL plasma

Other Acceptable Specimens

Draw two EDTA (lavender-top) tubes of whole blood. Spin one tube to separate plasma. Pour plasma into plastic aliquot tube (label this vial as plasma).

Send one 5 mL refrigerated uncentrifuged whole blood (4 mL minimum) and 1 mL refrigerated plasma (0.5 mL minimum).

Do not send packed cells. Do not send only one tube of whole blood.

Plasma cholinesterase results, as well as the calculated RBC cholinesterase results, are not accurate if plasma sample is not separated from the RBC's in a timely manner.

Hemolyzed plasma samples are not acceptable. Hemolysis can lead to apparent increases in plasma cholinesterase activity, and could mask an enzyme deficiency.

Transport Temperature
Refrigerated (cold packs)

Specimen Stability
Room temperature: 24 hours
Refrigerated: 7 days
Frozen: Unacceptable

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Kinetic Spectrophotometric (KS)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule
Set up: Tues-Sat; Report available: Next day

Elevated RBC values, caused by the presence of young RBCs and reticulocytes, may mask acetylcholinesterase inhibition. Plasma results may be depressed in patients who consume oral contraceptives. Hepatic disease may cause up to a 70% decrease in enzyme levels. Cholinesterase may be slightly elevated in patients with obesity or diabetes.

Reference Range
Cholinesterase, RBC 9572-15031 IU/L
Cholinesterase, Plasma  
  Male 3334-7031 IU/L
  Female 2504-6297 IU/L

Clinical Significance
True cholinesterase (RBC and plasma) activity is decreased in individuals with exposure to organophosphorous insecticides. True cholinesterase, found in erythrocytes and nerve tissue, is responsible for inactivating acetylcholinesterase at nerve endings. With decreased enzyme activity, patients may display a range of nervous system dysfunction. Analysis of RBC and serum or plasma activity is useful in monitoring exposure and recovery.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

Last Updated: November 29, 2021

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.