Definition of Cholinesterase - blood:

Serum cholinesterase is a blood test that looks at levels of two substances that help the nervous system work properly. They are called acetylcholinesterase and pseudocholinesterase. Your nerves need these substances to send signals.

Acetylcholinesterase is found in nerve tissue and red blood cells. Pseudocholinesterase is found primarily in the liver.

How the test is performed:

A blood sample is needed. For information on how this is done, see: Venipuncture

How to prepare for the test:

No special preparation is necessary for this test.

How the test will feel:

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed:

Your health care provider may order this test if you may have been exposed to chemicals called organophosphates, which are used in pesticides. This test can help determine your risk of poisoning.

Less often, this test may be done:

• To diagnose liver disease
• Before you receive anesthesia with succinylcholine, which may be given before certain procedures or treatments, including electroconvulsive therapy (ECT)

Normal Values:

Typically, normal pseudocholinesterase values range between 8 and 18 units per milliliter (U/mL).

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean:

Decreased pseudocholinesterase levels may be due to:

• Acute infection
• Chronic malnutrition
• Heart attack
• Liver damage
• Metastasis
• Obstructive jaundice
• Poisoning from organophosphates (chemicals found in some pesticides)

Smaller decreases may be due to:

• Pregnancy
• Use of birth control pills

What the risks are:

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken