Cholinesterase Test: What it is, What it’s For & Results Explained

What is cholinesterase?

Cholinesterase is an enzyme required for function in the nervous system and is responsible for breaking down acetylcholine (a neurotransmitter), so that it does not over-stimulate post-synaptic nerves, muscles, and exocrine glands. It can be affected by genetic factors and poisoning.

Exposure to organophosphate or carbamate pesticides can inhibit cholinesterase from breaking down acetylcholine.

Why would you need a cholinesterase test?

A doctor may measure you cholinesterase levels if you have been exposed to pesticides of the organophosphate or carbamate types.

Exposure to these pesticides may occurr via inhalation, ingestion or through the skin.

How is a cholinesterase test performed?

Cholinesterase is a blood test and requires a few millilitres of blood from a vein.

The laboratory may measure the levels of cholinesterase enzyme activity in the plasma or red blood cells, or both.

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Cholinesterase test results explained

Cholinesterase levels vary greatly between different individuals, and laboratories employ many different methods of testing. Therefore, a cholinesterase level is most useful when it is repeated in the same person, before and after exposure.

Results are usually expressed in terms of percentage drop from baseline; a decline of more than 35% is considered to indicate severe poisoning.

Plasma cholinesterase levels are more useful for acute (short-term) exposure, while red cell levels are more useful in the chronic (long-term) setting.

In a case of deliberate self-poisoning, the cholinesterase level may be low enough to diagnose organophosphate or carbamate poisoning, without a prior ‘baseline’ level.

Related specialists

Related procedures

  • Blood Test (venesection)

Related tests

Also known as

  • Plasma Cholinesterase levels
  • Red Cell Cholinesterase levels
  • Cholinesterase activity
  • Pseudocholinesterase



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This article is for informational purposes only and should not be taken as medical advice. If in doubt, HealthEngine recommends consulting with a registered health practitioner.

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