What is the Cholinesterase (Serum/Pseudo) Test?

The Cholinesterase (Serum/Pseudo) test measures the activity of pseudocholinesterase, an enzyme produced primarily by the liver and found in the bloodstream. This enzyme plays a key role in breaking down certain drugs, toxins and anaesthetic agents.

Unlike red blood cell cholinesterase, serum pseudocholinesterase is particularly useful for assessing exposure to organophosphate and carbamate pesticides, as well as evaluating liver synthetic function. Reduced enzyme activity may indicate toxic inhibition, genetic variants or impaired liver production.

This test is widely used in occupational health, toxicology and pre-operative assessment.

Why do I need a test for Cholinesterase (Serum/Pseudo)?

You may need this test if there is concern about exposure to pesticides, nerve agents or other cholinesterase-inhibiting substances. It is also useful before surgery to identify individuals at risk of prolonged paralysis from certain muscle relaxant anaesthetics.

Monitoring cholinesterase levels helps detect early toxic effects, guide workplace safety decisions and support clinical management following exposure.

Symptoms and scenarios where testing is recommended:

• Suspected pesticide or organophosphate exposure
• Occupational monitoring (agriculture, pest control)
• Nausea, dizziness or excessive sweating
• Muscle weakness or twitching
• Breathing difficulties
• Pre-operative anaesthetic assessment
• Known or suspected liver disease
• Family history of pseudocholinesterase deficiency

Benefits of the Cholinesterase (Serum/Pseudo) Test

• Detects toxic exposure effects
  Identifies enzyme inhibition from organophosphates.
• Supports occupational health monitoring
  Used in pesticide-exposed workers.
• Assesses liver enzyme production
  Reflects liver synthetic capacity.
• Identifies anaesthetic risk
  Detects susceptibility to prolonged muscle paralysis.
• Enables early intervention
  Identifies exposure before severe symptoms develop.
• Useful in acute and chronic exposure
  Supports short- and long-term monitoring.
• Clinically established toxicology marker
  Widely used in exposure assessment.
• Simple blood-based testing
  Requires only a standard blood sample.

Step-by-Step: How Testing Works

Choose your preferred testing method

You can attend one of our UK partner clinics or arrange a home or hotel visit with a mobile phlebotomist.

Option 1 – In-Clinic Blood Draw

1. Select your nearest UK clinic and book an appointment.
2. A clinician or phlebotomist collects a venous blood sample.
3. The sample is analysed for pseudocholinesterase activity.
4. Results are delivered securely online.

Option 2 – Home or Hotel Phlebotomy (+£60)

1. Book a UK-wide home or hotel visit at a convenient time.
2. A trained phlebotomist collects your blood sample on-site.
3. The sample is transported to the laboratory.
4. Results are uploaded digitally without the need to travel.

Your Results Explained

Low Levels

Reduced pseudocholinesterase activity may indicate organophosphate exposure, liver disease or inherited enzyme deficiency.
Low levels increase the risk of prolonged response to certain anaesthetic drugs.

Typical UK reference ranges vary by laboratory.

Normal Levels

Normal enzyme activity suggests no significant inhibition or liver production impairment.
This supports normal detoxification and drug metabolism capacity.

High Levels

Elevated levels are usually not clinically significant.
They may occasionally be seen in pregnancy or certain metabolic states.