To find out if you are likely to have temporary paralysis after being given a muscle relaxant called suxamethonium during surgery. This temporary paralysis is called suxamethonium apnoea.
To screen for exposure to the effects of organic phosphorus insecticides.
If you or a close relative have experienced suxamethonium apnoea after a surgical operation.
To indicate possible insecticide poisoning with recent or frequent use of organic phosphorus insecticides. Occupational exposure can occur in workers involved with agriculture or the organic chemical industry.
A blood sample taken from a vein in your arm
None
On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.
If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.
Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.
Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.
For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.
For more information on reference ranges, please read Reference Ranges and What They Mean.
There are two similar cholinesterase enzymes in the body; butrylcholinesterase (pseudocholinesterase) found in the blood plasma, intestine and white matter of the brain, and acetylcholinesterase found in red blood cells, grey matter of the brain and nerve endings.
Acetylcholine is a chemical which is involved in the transmission of signals across nerve endings and which is broken down by the enzyme acetylcholinesterase. Any decrease in this enzyme can cause a build-up of acetylcholine at nerve endings that in turn can lead to overstimulation of nerves in the body tissues.
Serum butyrylcholinesterase is the enzyme usually measured by the laboratory. This is because the enzyme can be used as a marker for the ineffective metabolism of the muscle relaxant suxamethonium used in surgery as well as exposure to organic phosphorus insecticides.
The laboratory measures the total activity of cholinesterase in the patient’s blood. This is useful because if the activity is low it suggests an atypical enzyme variant is present and that the patient is at risk of prolonged effects from the muscle relaxants suxamethonium or mivacurium. Also, low total enzyme activity in people working with organophosphorus compounds on farms or in the chemical industry may indicate acute exposure.
Inhibitor studies are also carried out to determine the patient’s phenotype which can be used to find out whether the enzyme is ‘usual’ or ‘atypical’ , provide more information about any potential risk and assist in family studies. In order to identify the cholinesterase phenotype the enzyme is incubated with a range of inhibitors which include dibucaine, fluoride and frequently Ro 02-0683, chloride and sometimes scoline. The percentage of the enzyme activity remaining is referred to as a ‘number’ and is used to assess the phenotype. In this way the laboratory can discover whether the patient has a usual (normal) or an atypical enzyme. The enzyme phenotype can be further classified into a number of possible variants with varying degrees of possible sensitivity to suxamethonium or mivacurium.
Genetic studies can also be indicated if an ‘atypical’ variant is difficult for the laboratory to identify or if a silent S gene is suspected. These tests are not as widely available as phenotype studies at present.
A blood sample taken from a vein in your arm.
No test preparation is needed.
Total cholinesterase activity can also be lowered in a number of other conditions. These include pregnancy, renal disease, shock, malnutrition and some cancers.
As cholinesterase is synthesised by the liver the activity can also be lower in some liver diseases such as acute and chronic hepatitis, advanced cirrhosis and liver metastases. However, normal levels can be found in mild hepatitis and cirrhosis as well as obstructive jaundice.
There may be a risk of a very mild prolonged reaction to suxamethonium in these conditions of minutes as opposed to hours, as long as these patients have lower activities of the usual enzyme rather than the atypical enzyme variant
On This Site
Tests: Dibucaine Inhibition; Liver Panel
Suxamethonium Apnoea
Elsewhere On The Web
Wikipedia: Cholinesterase
