To determine whether excessive ketones are present in the blood, to detect diabetic ketoacidosis (DKA), to detect alcoholic ketoacidosis and to monitor ketogenic diet therapy used in the treatment of epilepsy.
A blood sample taken from a vein in your arm or a drop of blood from your finger.
No test preparation is needed.
This test measures the amount of ketones in the blood. Ketones are produced during the break down of fats. They are made when glucose is not available as an energy source. When fatty acids are metabolised, ketones build up in the blood, causing first ketosis, and then ketoacidosis, a form of metabolic acidosis. This condition is most frequently seen with uncontrolled type 1 diabetes and can be a medical emergency.
There are three ketones or ketone bodies, acetoacetate, acetone, and beta-hydroxybutyrate, a reduced form of acetoacetate. Beta-hydroxybutyrate is the main ketone present in severe diabetic ketoacidosis (DKA). Ketone tests measure one or more ketone bodies and therefore test results may differ.
Blood testing gives a snapshot of the amount of ketones that have accumulated at the time that the sample was collected. Urine ketone testing shows recent rather than current blood ketones. Urine testing is much more commonly used than that for blood ketones. It may be performed by itself, with a urine glucose test, or as part of a a range of tests in urine called urinalysis. The urine methods measure either acetoacetate or both acetoacetate and acetone but they do not detect the other ketone beta-hydroxybutyrate.
Blood ketones can be measured in a laboratory or with a handheld monitor. The laboratory test uses serum or plasma, the liquid portion of the blood after the cells have been removed, to measure acetoacetate and/or beta-hydroxybutyrate. When whole blood from a fingerprick is tested for ketones using a handheld monitor, the monitor measures beta-hydroxybutyrate. This test may sometimes be done at a person’s bedside in a hospital and with the appropriate test device by a person at home.
How is it used?
Blood ketones are mainly used to screen for, detect, and monitor diabetic ketoacidosis (DKA) in people with type 1 and sometimes type 2 diabetes. DKA can occur when blood sugar is markedly increased, often due to illness, severe infection, pregnancy.
Diabetic ketoacidosis (DKA) is seen with rapidly increasing blood glucose, a severe lack of insulin, and a disruption of acid-base balance. Excess ketones and glucose are passed into the urine by the kidneys to flush them from the body. This causes increased urination, thirst, dehydration, and a loss of electrolytes. The affected person may also experience symptoms such as rapid breathing, shortness of breath, a fruit-scent to the breath (the smell of some of the ketones), feeling sick, vomiting, tiredness, confusion, and eventually coma. Ketosis and ketoacidosis may also be seen with starvation, alcoholism, and with high-fat low-carbohydrate diets.
Blood ketones are sometimes used, with other tests such as blood gases, glucose, and electrolytes to detect ketoacidosis in those who do not have diabetes but have signs and symptoms of diabetic ketoacidosis (DKA) due to, for example, ingestion of excessive amounts of alcohol.
When is it requested?
Blood ketone tests may be used when a person with diabetes has symptoms of DKA and may also be performed whenever there is the potential for DKA to develop, such as when someone with diabetes is sick or pregnant. Some signs and symptoms of ketoacidosis include:
- increased urination, excessive thirst
- dehydration, loss of electrolytes
- rapid breathing, shortness of breath
- a fruit-scent to the breath
- nausea, vomiting
- sometimes coma
In someone without diabetes, blood ketones are usually requested when the patient has symptoms of ketosis or ketoacidosis.
What does the test result mean?
If blood ketone concentrations are increased then the person has some degree of ketosis or ketoacidosis. If concentrations are low or normal then the person either does not have excess ketone production or the ketone body that is elevated is not being detected by the test method used.
Is there anything else I should know?
If I have diabetes can I just test for glucose instead of ketones?
They are related but not the same thing. While increases in ketones are associated with high glucose concentrations, they can also occur with moderate glucose levels in many conditions, such as when you are sick. People with diabetes often do tests for blood glucose but not for ketones.
Can I test for ketones in my urine instead of my blood?
Can I get DKA if I have type 2 diabetes?
Can I have ketosis or ketoacidosis and not know it?