Blood ketones (beta-hydroxybutyrate)
Acids the body makes when it breaks down fat instead of glucose for energy
Also known as
Definition
Ketones are acids made in the liver when the body breaks down fat for energy, for example because cells are not getting enough glucose. The body makes three types, including beta-hydroxybutyrate and acetoacetate. On a low-carbohydrate ketogenic diet they rise (ketosis). If they build up too much, the blood becomes too acidic: this ketoacidosis is an emergency, most often as a complication of diabetes.
| Parameter | Value |
|---|---|
| Unit | Lab report negative/positive or as a number; unit as stated on the report or meter |
| Reference Range | In adults, a negative lab result is usually considered normal; according to MedlinePlus, small amounts of ketones are normal. The sources used here do not give a fixed numeric range. Labs and methods differ; the range printed on your report is what counts, and your doctor interprets the result. |
Agree on your personal target range with your doctor.
↓ What a low value means
A negative or normal result usually means the body is not making too many ketones and there is no ketoacidosis. It does not always rule out diabetic ketoacidosis, though: in the early stages, often only one of the three types of ketones is raised, and lab tests often do not measure that type. If symptoms are present, the medical assessment counts, not the reading alone.
↑ What a high value means
A raised or positive result shows ketones in the blood. On a low-carbohydrate ketogenic diet, levels can be raised without reaching the level of ketoacidosis (ketosis). Very high levels together with symptoms can be linked to ketoacidosis, such as diabetic or alcoholic ketoacidosis, or to starvation and malnutrition. Other possible links are uncontrolled blood sugar in diabetes, recent anesthesia, glycogen storage disease and medicines from the SGLT2 inhibitor group. Extreme thirst, frequent urination, nausea, vomiting, abdominal pain, confusion, trouble breathing or fruity-smelling breath need immediate medical help.
When to test
Mainly in diabetes, to catch ketoacidosis early, for example during illness, in pregnancy or with gestational diabetes. Without diabetes, when there is a raised risk and matching symptoms, including on a low-carbohydrate diet. No special preparation is needed. Home meters that use a drop of blood from a fingertip are available; talk with your doctor about how and when to test.
Frequently asked questions
What is the difference between ketosis and ketoacidosis? +
In ketosis, for example on a ketogenic diet, ketones are raised but the body uses them, so the blood does not become too acidic. In ketoacidosis, so many ketones build up that the blood becomes acidic. This is an emergency. Ketoacidosis can also develop on a ketogenic diet; talk with your doctor about whether this diet is suitable for you.
Can I measure ketones at home? +
Yes. There are meters that measure glucose and ketones from a drop of blood from a fingertip, as well as urine test strips. The instructions should be followed carefully. Talk with your doctor about which method suits you and what to do if levels are high.
Does a negative result rule out ketoacidosis? +
Not always. The body makes three types of ketones. In the early stages of diabetic ketoacidosis, often only one of them is raised, and lab tests often do not measure it. If symptoms are present, a medical assessment is what counts.
Can medicines affect the result? +
Yes. Medicines from the SGLT2 inhibitor group can raise blood ketones as a side effect and can be linked to ketoacidosis. Ketones can also be detectable after anesthesia. Never stop medicines on your own.
Blood ketones (beta-hydroxybutyrate)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.