Cholinesterase
Enzymes in the blood that the nervous system needs to transmit signals
Also known as
Definition
The cholinesterase blood test looks at two enzymes that nerves need to send signals: acetylcholinesterase, found in nerve tissue and red blood cells, and pseudocholinesterase (also called butyrylcholinesterase), found mainly in the liver. The level is measured mainly after possible exposure to organophosphates, chemicals used in pesticides, and less often to investigate liver disease or before anaesthesia with succinylcholine.
| Parameter | Value |
|---|---|
| Unit | U/l (also kU/l) |
| Reference Range | Typically about 3100–6500 U/l (3.1–6.5 kU/l) in adults. The level also varies from person to person. Labs differ; the range printed on your report is what counts, and your doctor interprets the result. |
Agree on your personal target range with your doctor.
If your report gives the value in kU/l: 1 kU/l = 1000 U/l. So 3100–6500 U/l corresponds to 3.1–6.5 kU/l.
↓ What a low value means
A low pseudocholinesterase level can be linked to, among other things, an inherited pseudocholinesterase deficiency, liver damage, jaundice caused by a blocked bile flow (obstructive jaundice), chronic infection, chronic malnutrition, a heart attack, metastases, inflammation that accompanies some diseases, or organophosphate poisoning. Smaller decreases can be linked to pregnancy or taking birth control pills. A single value does not allow a diagnosis; discuss any deviations with your doctor.
↑ What a high value means
MedlinePlus only describes the meaning of low cholinesterase levels; the source gives no separate interpretation of raised levels. If your value is above your lab's reference range, your doctor will interpret it in the context of your other results.
When to test
Mainly after possible exposure to organophosphates, for example in pesticides. Less often to investigate liver disease or before anaesthesia in which succinylcholine is used. No special preparation is usually needed. Because the level varies from person to person, a baseline value measured earlier makes the test more accurate.
Frequently asked questions
Why is cholinesterase sometimes measured before anaesthesia? +
MedlinePlus lists anaesthesia with succinylcholine, which may be given for example before electroconvulsive therapy, as one of the less common reasons for the test. Whether it is needed before a procedure is decided by the care team.
What do pesticides have to do with this value? +
Organophosphates are chemicals used in some pesticides. Poisoning with them can be linked to a low cholinesterase level. The test can therefore help assess the risk of poisoning after possible exposure. If you suspect poisoning, get medical help right away.
Why is a baseline value useful? +
Cholinesterase levels differ from person to person. A baseline value measured earlier makes the test more accurate, because a later value can then be compared with your own baseline and not only with the general reference range.
Can pregnancy or the pill affect the level? +
Yes. Pregnancy and taking birth control pills can be linked to smaller decreases in the level. So let your practice know if either applies to you.
Cholinesterase
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.