Cholinesterase blood test
Quick answer: A cholinesterase test measures the activity of enzymes that break down certain nerve chemicals and some medicines. Doctors order it to check for exposure to organophosphate pesticides, or before surgery to see if you may react strongly to certain anaesthetic muscle relaxants.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
How the test is done
- 1You tell staff about any pesticide exposure or planned surgery
- 2A band is tied around your upper arm
- 3A needle draws blood from a vein in your arm
- 4The sample is tested for cholinesterase enzyme activity
What your results can mean
Reading your report
Normal ranges differ between labs and by age and sex, so discuss your result with your doctor.
If the result is outside the usual range
A low level can be seen with organophosphate pesticide exposure, an inherited enzyme variant, liver disease, pregnancy or malnutrition. A low result before surgery can mean a stronger reaction to certain muscle relaxants.
Who usually has this test
Farm and pesticide workers, people with suspected poisoning, and people with a personal or family history of slow recovery from anaesthesia.
Risks and aftercare
You may have slight soreness or bruising at the needle site.
Names and options
Also called: pseudocholinesterase, butyrylcholinesterase, acetylcholinesterase
Options
- Cholinesterase
- Acetylcholinesterase
Listed by the hospital as
- ACETYLECHOLINE ESTERASE, SERUM
- CHOLINESTERASE, SERUM
Questions about this test
Why is a cholinesterase test done before surgery?
Some people have an inherited enzyme variant that breaks down certain anaesthetic muscle relaxants slowly. This can cause prolonged weakness after surgery, so the anaesthetist may want to know beforehand.
How does pesticide exposure affect cholinesterase?
Organophosphate and carbamate pesticides block cholinesterase, so the level falls. Repeat tests can help track exposure in people who work with them.
What is the difference between acetylcholinesterase and pseudocholinesterase?
Acetylcholinesterase is found mainly on red blood cells and nerves, while pseudocholinesterase is found in the liquid part of blood. Your doctor chooses which to measure depending on the reason for testing.
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.