Cholinesterase, RBC and Plasma (California Clients)

Test Code

90372

CPT Codes
82480, 82482<br>**This test is for California patients. For non-California patient testing, use test code 338.**

Preferred Specimen

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

Minimum Volume

4 mL whole blood • 0.5 mL plasma

Other Acceptable Specimens

Plasma collected in: PPT potassium EDTA (white-top) tube

Instructions

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 RBCs 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.

Note: PPT potassium EDTA (white-top) tubes should be centrifuged within 24 hours.

Transport Temperature

Refrigerated (cold packs)

Specimen Stability

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

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

Hemolysis • Lipemia • Received room temperature • Received frozen • Receipt of only a single tube of whole blood

Methodology
Kinetic Spectrophotometric (KS)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics Nichols Institute. 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

Night Sets up 5 days a week.

Limitations

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.

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.

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.