Ketones in Blood

Urgent safety information

If you have severe symptoms of ketoacidosis, seek immediate medical help. Large amounts of ketones can be life-threatening.

Why this test may be ordered

• To check for diabetic ketoacidosis (DKA) in people with diabetes, especially when sick or pregnant
• If you have symptoms of ketoacidosis such as extreme thirst, frequent urination, nausea, abdominal pain, confusion, or fruity-smelling breath
• If you have conditions that increase risk for high ketones, such as eating disorders, starvation, prolonged vomiting or diarrhea, or alcohol use disorder
• If you eat a low-carbohydrate diet and have symptoms

Preparation and collection

You don't need any special preparations for a ketones in blood test.

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. This usually takes less than five minutes.

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

Understanding results

Your test results will show whether ketones are detected in your blood. A normal result usually means your body is not making too many ketones, but a normal result does not always rule out diabetic ketoacidosis (DKA) because early DKA may involve a type of ketone that is not measured by standard lab tests. A high result means you have ketones in your blood. It is normal to have some blood ketones, but very high levels with symptoms may indicate ketoacidosis. Discuss your results with your healthcare provider.

• Normal or negative: Your body is not making too many ketones and you likely do not have ketoacidosis. However, a normal result does not always rule out diabetic ketoacidosis (DKA) because early DKA may involve a type of ketone not measured by standard lab tests. Limitation: A normal result may miss early DKA if only one type of ketone is elevated and the test does not measure that type. Next step: If you have symptoms, your provider may recommend additional testing or monitoring.
• High or positive: You have ketones in your blood. If levels are very high and you have symptoms, you may have ketoacidosis. If you have diabetes, you likely have diabetic ketoacidosis (DKA). If you don't have diabetes, you may have ketoacidosis from alcohol use disorder, malnutrition, not eating for very long periods, or other conditions. Limitation: Ketoacidosis from any cause must be treated. People on a low-carbohydrate ketogenic diet may have higher ketone levels (ketosis) that are not high enough to be ketoacidosis, but it is possible to develop ketoacidosis on a keto diet. Next step: Treatment may include going to the hospital. Talk with your provider about what to do if your levels are high.

• A normal test result does not always rule out diabetic ketoacidosis (DKA) because early DKA may involve a type of ketone not measured by standard lab tests.
• People on a low-carbohydrate ketogenic diet may have higher ketone levels (ketosis) that are not high enough to be ketoacidosis, but it is possible to develop ketoacidosis on a keto diet.
• At-home testing may have variability; follow instructions carefully and discuss with your provider.

What to do next

If you have questions about your results, talk with your provider. If you have diabetes and your ketone levels are high, follow your diabetes management plan and seek medical attention as advised. If you have severe symptoms of ketoacidosis, seek immediate medical help.

• What do my ketone levels mean for my diabetes management?
• How often should I test my ketones, and when is the best time to test?
• What should I do if my ketone levels are high?
• Are there any symptoms I should watch for that might indicate ketoacidosis?
• Is at-home testing for ketones in blood or urine right for me?

Evidence source

U.S. National Library of Medicine: Ketones in Blood