The cholinesterase test measures the level of cholinesterase in your blood. This enzyme helps break down acetylcholine, a neurotransmitter that carries nerve signals to muscle fibers.
This test is most often used for people who may be exposed to toxic chemicals at work, especially farmers. It can also be used to help monitor certain liver conditions.
There are two main types of cholinesterase that can be measured. One is acetylcholinesterase (found in red blood cells), and the other is plasma cholinesterase (made in the liver, pancreas, and small intestine and found in blood plasma).
Indications for testing
Healthcare providers typically order a cholinesterase test to monitor a person’s exposure to chemicals, such as insecticides and other agricultural substances, especially in farm workers.
It may also be ordered to monitor people with liver disease, especially those who have had a liver transplant, since they often have lower cholinesterase levels.
Cholinesterase testing may also be recommended for people with genetic mutations that affect how this enzyme is produced or how well it works.
Normal values
Normal cholinesterase values are:
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Men: 4,620 to 11,500 U/L;
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Women: 3,930 to 10,800 U/L.
Reference ranges can vary depending on the laboratory and the test kit used.
This test is done by taking a small blood sample and sending it to a lab for analysis. Depending on the lab, you may be asked to fast for at least 4 hours beforehand.
Interpreting results
High or low cholinesterase levels may indicate:
1. High cholinesterase
High cholinesterase may be caused by:
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Hyperthyroidism;
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Obesity;
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Nephrotic syndrome;
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Diabetes.
Children with certain developmental or cognitive differences may also have higher-than-typical cholinesterase levels in their blood.
2. Low cholinesterase
Low cholinesterase mainly suggests prolonged exposure to organophosphate pesticides. These substances are found in some insecticides, pesticides, and herbicides and can block this enzyme’s activity, which may lead to a buildup of acetylcholine and cause symptoms such as:
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Abdominal cramps;
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Diarrhea;
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Vomiting;
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Excessive salivation;
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Vision problems;
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Low blood pressure;
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Muscle weakness;
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Paralysis.
According to the Centers for Disease Control and Prevention (CDC), sudden organophosphate poisoning can cause symptoms such as weakness, diarrhea, nausea and vomiting, and excess salivation, among others.
Although low cholinesterase is most commonly linked to poisoning, levels may also be low in hepatitis, cirrhosis, congestive heart failure, acute infection, and heart attack.
Because of this, cholinesterase results should always be interpreted along with other tests so the doctor can identify possible causes and recommend the most appropriate treatment.