Test Id : PCHE1
Pseudocholinesterase, Total, Serum
Useful For
Suggests clinical disorders or settings where the test may be helpful
Monitoring exposure to organophosphorus insecticides and herbicides
Monitoring patients with liver disease, particularly those undergoing liver transplantation
Identifying patients who are homozygous or heterozygous for an atypical gene and have low levels of pseudocholinesterase
This test is not useful for the differential diagnosis of jaundice.
Highlights
Pseudocholinesterase (PCHE) testing has two main uses:
-Monitoring for toxic exposure in people who work with organophosphate compounds by establishing a baseline PCHE activity level. Then routine testing is used to monitor for a significant reduction in PCHE activity.
-Preoperative screening for patients with a history or family history of prolonged paralysis and apnea after the use of the muscle relaxant, succinylcholine, for anesthesia
This test can also diagnose acute organophosphate insecticide and herbicide exposure.
Method Name
A short description of the method used to perform the test
Colorimetric Assay
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Butyrylcholinesterase
Cholinesterase (Pseudo), Total
Serum Cholinesterase (Pseudochol)
Specimen Type
Describes the specimen type validated for testing
Serum
Necessary Information
Patient's age and sex are required.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Patient Preparation: For patients with prolonged apnea following surgery, wait at least 24 hours before obtaining specimen.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions:
1. Serum gel tubes should be centrifuged within 2 hours of collection.
2. Red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial within 2 hours of collection.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.25 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Ambient | 24 hours | ||
| Frozen | 365 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Monitoring exposure to organophosphorus insecticides and herbicides
Monitoring patients with liver disease, particularly those undergoing liver transplantation
Identifying patients who are homozygous or heterozygous for an atypical gene and have low levels of pseudocholinesterase
This test is not useful for the differential diagnosis of jaundice.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Serum cholinesterase, often called pseudocholinesterase (PCHE), is distinguished from acetylcholinesterase, or "true cholinesterase," by both location and substrate.
Acetylcholinesterase is found in erythrocytes, lungs and spleen, nerve endings, and gray matter of the brain. It is responsible for the hydrolysis of acetylcholine released at the nerve endings to mediate transmission of the neural impulse across the synapse.
PCHE, the serum enzyme, is found in the liver, pancreas, heart, and white matter of the brain. Its biological role is unknown.
The organophosphorus-containing insecticides and herbicides are potent inhibitors of the true cholinesterase and cause depression of PCHE. Low values of PCHE are also found in patients with liver disease. In general, patients with advanced cirrhosis and carcinoma with metastases will show a 50% to 70% decrease. Essentially normal values are seen in chronic hepatitis, mild cirrhosis, and obstructive jaundice.
PCHE metabolizes the muscle relaxants succinylcholine and mivacurium, and therefore, alterations in PCHE will influence the physiologic effect of these drugs.
In normal individuals (approximately 94% of the population), certain drugs and other agents such as dibucaine and fluoride will almost completely inhibit the PCHE activity.
A small number of individuals (<1% of the population) have been shown to have genetic variants of the enzyme and, therefore, cannot metabolize the muscle relaxants succinylcholine and mivacurium and experience prolonged apnea. These individuals generally have low levels of PCHE, which is not inhibited by dibucaine or fluoride. These individuals are either homozygous or compound heterozygous for an atypical gene controlling PCHE.
Simple heterozygous individuals have also been identified who show intermediate enzyme values and inhibition.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Males
5320-12,920 U/L
Females
0-15 years: 5320-12,920 U/L
16-39 years: 4260-11,250 U/L
40-41 years: 5320-12,920 U/L
> or =42 years: 5320-12,920 U/L
Note: Females aged 18-41 years who are pregnant or taking hormonal contraceptives, the reference interval is 3650-9120 U/L.
Interpretation
Provides information to assist in interpretation of the test results
Patients with normal pseudocholinesterase (PCHE) activity show 70% to 90% inhibition by dibucaine, while patients homozygous for the abnormal allele show little or no inhibition (0%-20%) and usually low levels of enzyme.
Heterozygous patients have intermediate PCHE levels and response to inhibitors.
The atypical gene is inherited in an autosomal recessive pattern. In a positive patient, family members should be tested.
Decreasing or low levels may indicate exposure to organophosphorus insecticides or herbicides if liver disease and an abnormal allele have been ruled out.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
There are some homozygous and heterozygous individuals who are sensitive to succinylcholine although their total pseudocholinesterase (PCHE) values are normal. A dibucaine inhibition test is necessary to confirm the presence of the abnormal allele in these individuals.
Certain drugs and anesthetic agents may produce in vitro inhibition of the PCHE activity. Therefore, it is recommended that blood specimens be drawn 24 to 48 hours post-operatively on those patients who have experienced prolonged apnea after surgery.
Chemotherapy may interfere with test results, depending on the impact it has on the liver. PCHE levels may be lower due to this, and if so, testing should be repeated at a later date.
Method Change: Pseudocholinesterase values measured after 01/28/2020 are approximately 80% increased compared to historical values and should be interpreted in the context of the current reference interval.
In very rare cases of gammopathy, particularly type IgM (Waldenstrom macroglobulinemia), may cause unreliable results.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Soliday FK, Conley YP, Henker R. Pseudocholinesterase deficiency: A comprehensive review of genetic, acquired, and drug influences. AANA J. 2010;78:313-320
2. Robles A, Michael M, McCallum R. Pseudocholinesterase deficiency: What the proceduralist needs to know. Am J Med Sci. 2019;357(3):263-267. doi:10.1016/j.amjms.2018.11.002
3. Lurati AR. Organophosphate exposure with pseudocholinesterase deficiency. Workplace Health and Saf. 2013;61(6):243-245. doi:10.1177/216507991306100602
4. den Blaauwen DH, Poppe WA, Tritschler W. Cholinesterase (EC 3.1.1.8) with butyrylthiocholine-iodide as substrate: References depending on age and sex with special reference to hormonal effects and pregnancy. J Clin Chem Clin Biochem. 1983;21:381-386
Method Description
Describes how the test is performed and provides a method-specific reference
Cholinesterase catalyzes the hydrolysis of butyrylthiocholine to thiocholine and butyrate. Thiocholine instantaneously reduces the yellow hexacyanoferrate (III) to the almost colorless hexacyanoferrate (II). This decrease in color can be measured photometrically.(Package insert: Cholinesterase Gen 2 Reagent. Roche Diagnostics; V.10.0, 01/2022)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Friday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
82480
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| PCHE1 | Pseudocholinesterase, Total, S | 2098-2 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| PCHE1 | Pseudocholinesterase, Total, S | 2098-2 |