Cholinesterase
Also known as: Pseudocholinesterase, BChE
What Does Cholinesterase Measure?
Cholinesterase (also called pseudocholinesterase or butyrylcholinesterase, BChE) is an enzyme primarily produced by the liver that circulates in the blood plasma. A blood test measuring cholinesterase assesses the activity level of this enzyme, which plays a role in breaking down certain chemicals, including the neurotransmitter acetylcholine and some medications used during anesthesia (such as succinylcholine). Unlike acetylcholinesterase found in red blood cells, pseudocholinesterase is the form most commonly measured in routine plasma tests.
Why Does Cholinesterase Matter?
Cholinesterase is an important marker of liver synthetic function, as the liver is responsible for producing this enzyme. Reduced levels can signal liver disease, organophosphate or carbamate pesticide poisoning, or rare genetic variants that affect anesthesia metabolism. It is routinely checked before surgery to identify patients at risk of prolonged paralysis from certain anesthetic agents. In occupational medicine, it is used to monitor workers exposed to pesticides. Elevated levels, while less clinically urgent, may indicate conditions such as nephrotic syndrome, obesity, or hyperthyroidism.
Normal Ranges
Males
4,900–11,900 U/L (units may vary by lab; some report 3,930–10,800 U/L)
Females
3,650–9,800 U/L (slightly lower than males; some labs report 3,430–8,600 U/L)
Children
Varies by age; generally similar to adult ranges by late childhood; neonates may have lower values
Causes of High Levels
- Nephrotic syndrome (protein loss triggers increased liver enzyme production)
- Obesity and metabolic syndrome
- Hyperthyroidism (increased metabolic activity elevates enzyme production)
- Type 2 diabetes mellitus
- Alcoholic fatty liver disease in early stages
- Certain medications including corticosteroids and oral contraceptives
Causes of Low Levels
- Organophosphate or carbamate pesticide poisoning (these chemicals inhibit the enzyme)
- Acute or chronic liver disease including hepatitis, cirrhosis, and liver failure
- Malnutrition or prolonged fasting (reduced substrate for enzyme synthesis)
How to Improve Your Cholinesterase
Diet
- Increase protein intake (lean meats, eggs, legumes) to support liver enzyme synthesis
- Eat foods rich in choline such as eggs, liver, salmon, and sunflower seeds to support liver health
- Reduce alcohol consumption, as alcohol directly suppresses liver enzyme production
- Consume antioxidant-rich vegetables (broccoli, spinach, carrots) to protect liver cells
- Stay adequately hydrated with 6–8 glasses of water daily to support liver metabolism
Supplements
- Milk thistle (silymarin) 140–420 mg/day to support liver regeneration and enzyme production
- N-acetylcysteine (NAC) 600–1800 mg/day as a liver-protective antioxidant
- Choline 400–550 mg/day (adequate intake) to support liver synthetic function
- B-complex vitamins (especially B6, B12, and folate) to support enzymatic pathways
- Alpha-lipoic acid 300–600 mg/day as a hepatoprotective antioxidant
Related Biomarkers
Frequently Asked Questions
What is the difference between pseudocholinesterase and acetylcholinesterase?
Pseudocholinesterase (BChE) is produced by the liver and found in blood plasma, while acetylcholinesterase is found mainly in red blood cells and nerve tissue. Both break down similar compounds, but pseudocholinesterase is measured in most routine blood tests and is particularly relevant for liver function and anesthesia safety. Acetylcholinesterase is more specific to nerve function and is sometimes tested separately in pesticide poisoning cases.
Why is cholinesterase tested before surgery?
Some anesthetic drugs, particularly succinylcholine (a muscle relaxant used during intubation), are broken down by pseudocholinesterase. People with low or genetically abnormal cholinesterase activity cannot metabolize these drugs efficiently, leading to prolonged muscle paralysis — a condition called 'scoline apnea.' A pre-operative cholinesterase test (or genotyping) helps anesthesiologists choose safe alternatives and avoid potentially dangerous complications.
Can low cholinesterase levels indicate pesticide poisoning?
Yes. Organophosphate and carbamate pesticides work by inhibiting cholinesterase enzymes, causing dangerous accumulation of acetylcholine in the nervous system. A significant drop in blood cholinesterase activity is a key diagnostic marker for acute pesticide poisoning and is also used to monitor chronic low-level exposure in agricultural workers. Symptoms include excessive sweating, muscle twitching, nausea, and in severe cases, seizures or respiratory failure.