Liver and pancreas
Cholinesterase
An enzyme from the liver; shows how sensitive someone is to certain muscle relaxants and says something about the liver.
Everything about this testWhat it measures
The test measures the activity of pseudocholinesterase (butyrylcholinesterase), an enzyme that the liver makes and releases into the blood. The enzyme breaks down certain substances, including the muscle relaxant succinylcholine that is used during general anesthesia. Because the liver makes the enzyme, its activity is also a measure of how much protein the liver can produce. In addition, some insecticides (organophosphates) inhibit the enzyme.
- An inherited reduced activity of the enzyme, which makes certain muscle relaxants work longer during general anesthesia
- A reduced production function of the liver
- Poisoning with organophosphate insecticides
High
A raised activity occurs with overweight, fatty liver, a raised fat level in the blood, diabetes and with protein loss through the kidneys. A raised value causes no symptoms itself and usually has little meaning.
Low
According to the Dutch Society for Clinical Chemistry (NVKC), a low activity usually has an inherited cause: an abnormality in the structure of the enzyme. People who have this notice nothing in daily life, but can remain paralyzed much longer than expected after general anesthesia with succinylcholine. A low value can also fit severely reduced liver function, malnutrition, a serious illness or poisoning with organophosphate insecticides. Pregnancy, the contraceptive pill and some medicines slightly lower the value without there being a disease.
If your result is abnormal
With a clearly low value, it is especially important that the anesthesiologist knows this before any surgery; sometimes further testing for the inherited variant follows, and family members may then also have increased sensitivity. With a low value together with other abnormal liver results, the GP looks at the cause of the liver function disorder.
Reliability
A clearly low activity reliably points to increased sensitivity to succinylcholine; which inherited variant is behind it only becomes clear from further testing with inhibitors or DNA. As a measure of liver function, cholinesterase is less specific than albumin and the clotting time (PT or INR), because diet, pregnancy and medicines also lower the value. In people without symptoms, a slightly abnormal value says little.
Limitations
- Pregnancy, the contraceptive pill and other estrogens lower the activity without disease.
- Some medicines, such as certain cancer drugs, cyclophosphamide and neostigmine, lower the activity.
- Overweight, fatty liver and a high fat level in the blood raise the value.
- Reference values and the measurement method differ between laboratories; results from different laboratories are not easy to compare.
How common is this
An inherited reduced activity of the enzyme is not rare: about 1 in 25 to 30 people of European descent carry one abnormal variant, which at most slightly lowers the activity. A severe form, in which both genes are affected, occurs in about 1 in 3,000 to 5,000 people.
Who is this useful for
The result is mainly meaningful before general anesthesia in someone who themselves, or a family member, previously remained paralyzed for an unusually long time after surgery, when poisoning with insecticides is suspected and as an addition with known liver disease. In people without symptoms, a slightly abnormal value says little.
Downsides and risks
- A slightly low value due to pregnancy, the pill or medicines can wrongly be read as a liver problem or inherited abnormality.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results