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Test ID: ACHS Acetylcholinesterase, Erythrocytes

Reporting Name

Acetylcholinesterase, RBC

Useful For

Detecting effects of chronic or remote (months) past exposure to cholinesterase inhibitors (organophosphate insecticide poisoning)

Clinical Information

Erythrocyte acetylcholinesterase (AChE) activity is measured to evaluate possible exposure to organophosphate insecticides. Organophosphates act by irreversible inhibition of AChE. Inhibition of AChE in humans causes a variety of acute symptoms including dizziness, nausea, difficulty breathing, and even death. The presence and severity of these symptoms depend, in part, on the degree of AChE depression.


Occupational pesticide handlers are at an elevated risk for exposure to these chemicals through skin contact, inhalation, or accidental ingestion. Organophosphate intoxication can be a result of one or more high exposure events or through chronic lower-level exposure.


Both serum and erythrocyte cholinesterase activity are inhibited by these insecticides, which are among the most commonly used pesticides in the United States. The half-life of serum cholinesterase (eg, pseudocholinesterase) is about 8 days, while the half-life of AChE in erythrocytes is between 2 and 3 months. Therefore, erythrocyte AChE is an indicator of chronic and temporally distant exposures to organophosphates.


Activities less than normal are suspect for exposure to certain insecticides. For occupational high-risk individuals, a pre-exposure "baseline" is recommended.

Report Available

4 to 8 days

Day(s) Performed


Clinical Reference

1. Brahmi N, Mokline A, Kouraichi N, et al: Prognostic value of human erythrocyte acetylcholinesterase in acute organophosphate poisoning. Am J Emerg Med. Nov 2006;24(7):822-827. doi: 10.1016/j.ajem.2006.05.009

2. Strelitz J, Engel LS, Keifer MC: Blood acetylcholinesterase and butyrylcholinesterase as biomarkers of cholinesterase depression among pesticide handlers. Occup Environ Med. 2014;71(12):842-847. doi: 10.1136/oemed-2014-102315

3. Mason HJ: The recovery of plasma cholinesterase and erythrocyte acetylcholinesterase activity in workers after over-exposure to dichlorvos. Occup Med (Lond). 2000;50(5):343-347. doi: 10.1093/occmed/50.5.343

4. Assis CR, Linhares AG, Cabrera MP, et al: Erythrocyte acetylcholinesterase as a biomarker of pesticide exposure: new and forgotten insights. Environ Sci Pollut Res. 2018;25:18364-18376. doi: 10.1007/s11356-018-2303-9

5. Robinson DG, Trites DG, Banister EW: Physiological effects of work stress and pesticide exposure in tree planting by British Columbia silviculture workers. Ergonomics. 1993 Aug;36:951-961. doi: 10.1080/00140139308967959

6. Fuortes LJ, Ayebo AD, Kross BC: Cholinesterase-inhibiting insecticide toxicity. Am Fam Phys. 1993 May;47:1613-1620

Method Name

Spectrophotometric-Thiocholine Production

Specimen Type

Whole Blood EDTA

Ordering Guidance

For testing succinylcholine sensitivity to anesthesia, order PCHE1 / Pseudocholinesterase, Total, Serum.

Shipping Instructions

Specimen must arrive within 72 hours of collection.

Necessary Information

Date of collection is required.

Specimen Required

Container/Tube: Lavender top (EDTA)

Specimen Volume: 4 mL

Collection Information: Send whole blood specimen in original tube. Do not aliquot.

Specimen Minimum Volume

2.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated 72 hours

Reference Values

31.2-61.3 U/g of hemoglobin


Reference values have not been established for patients younger than 18 years of age.

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
ACHS Acetylcholinesterase, RBC 49230-6


Result ID Test Result Name Result LOINC Value
ACHSR Acetylcholinesterase, RBC 49230-6
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