Ketones are chemicals produced by your liver cells when your body breaks down fat for energy. Ketone levels can rise slightly during exercise, fasting, or sleep.1

What Is a Ketone Test?

A healthcare provider may order a ketone test through your blood, urine, or breath to check for elevated ketone levels.2

Your ketone levels will become elevated whenever your body's primary source of energy shifts from glucose (sugar) to fat (ketones). Ketone levels can increase slightly during alcohol use, exercise, fasting, and sleep.1

Metabolic conditions like diabetes may cause ketone levels to significantly elevate to a state called diabetic ketoacidosis (DKA), when your body cannot convert glucose into energy because it does not produce enough insulin. Instead, it will break down fats for energy, which can produce a harmful level of ketones.3

Nutritional ketosis, the main goal of the keto diet, is a state of moderately high blood levels of ketones. The keto diet is low in carbohydrates and high in fats and protein. Ketone levels are increased during ketosis, but they are typically not dangerously elevated.4

Who Needs To Test?

Certain risk factors can increase the likelihood of high ketone levels. A healthcare provider may recommend a ketone test if you have risk factors like:5

• Alcohol use disorder (AUD)
• Diabetes
• Digestive disorders
• Eating disorders
• Keto diet 
• Long-term fasting
• Pregnancy
• Regular strenuous exercise

What Are the Symptoms?

A healthcare provider may also order a ketone urine test if you have symptoms of ketoacidosis, dangerously high levels of ketones in the blood. Symptoms include:6

• Abdominal pain
• Achy or stiff muscles
• Breath that smells fruity
• Dry mouth or skin
• Fatigue 
• Frequent urination
• Headache
• Increased thirst
• Nausea or vomiting
• Rapid, deep breathing

How Do You Check Ketone Levels?

There are several tests to check ketone levels, including urine, blood, and breath tests. You can perform some of these tests at home, or a healthcare provider can administer them in a clinical setting. 

Urine Test

People who are at risk of developing DKA may need regular at-home testing with urine strips. You may pee directly on the urine strip or collect your urine in a cup and dip the strip in the cup.5

Providing a urine test in a hospital or medical office is similar to taking any other urine sample. A healthcare provider will give you a container and instruct you to collect a "clean catch" sample. This involves the following considerations:

• The first few drops contain bacteria, so it's best to first urinate in the toilet before collecting the sample.
• Do not touch the container to your skin, as this can contaminate the sample with bacteria.5

The medical lab will test your urine ketone levels and send you the results. It's best to discuss your results with a healthcare provider to determine what they mean for you.5

Blood Test

A blood test detects a different type of ketone in the blood, known as beta-hydroxybutyrate. It's the first one to increase in people with diabetes and is usually not present in your urine.7

People with kidney disease also require a blood test. Your body cannot excrete ketone in your urine if you have kidney disease. Even elevated ketone levels will not be detected in your urine.7

A healthcare provider will typically take a sample of your blood from the large vein in your arm and send it to the lab for testing. You may experience some pain in the injection site.6

Make sure to read the packaging and the guidelines carefully if you perform a blood test at home with ketone strips. A strip test is typically done by pricking the skin, adding a drop of blood to the ketone strip, and inserting the strip into a blood ketone meter.7

Breath Test

A healthcare provider may order a breath test if they need to rapidly check for elevated levels of ketones. This test detects a ketone called acetone in your breath. Acetone gives your breath a fruity smell.8

You will breathe into a breath analyzer, which measures acetone levels in the breath you exhale.8

What Do the Results Mean?

Your ketone levels are not elevated if your test results are normal or negative.

Some people, such as those with diabetes or kidney disease, may show a normal value on a urine test and have increased levels on a blood test.6

Results that show moderate ketone levels indicate your levels are mildly elevated, which may not be a cause for concern. A healthcare provider might ask you to test more regularly and watch for specific symptoms of ketoacidosis.6

Your ketone levels are elevated if your test results are high or positive. It's important to contact a healthcare provider right away if you take an at-home test.

You may be at risk for DKA if you have diabetes and your blood test shows ketone levels greater than 3 millimoles per liter.6

Ketone Levels Millimoles per liter (mmol/L) Normal  Less than 0.6 Low to moderate  0.6-1.5  High  1.6-3.0  Dangerously highMore than 3.0

How Do You Treat It?

A healthcare provider can administer treatments if you are diagnosed with ketoacidosis. The goal of treatment is to bring your ketone levels back to a normal range.9

Treatments include:10

• Electrolyte replacement
• Fluid replacement
• Intravenous (IV) insulin

These treatments also ease symptoms like a loss of appetite, frequent urination, and vomiting. Most people recover within 24 hours.9 Some people may require frequent monitoring in the intensive care unit (ICU).10

How Can You Prevent It?

You can take steps to prevent ketoacidosis if you have a condition that increases your risk, such as diabetes. Make sure that you:2

• Maintain normal blood sugar levels, such as by eating a nutrient-rich diet and staying physically active. 11
• Regularly check your blood sugar levels.
• Speak with a healthcare provider about how to adjust your insulin based on factors like activity, diet, and illness.
• Take any prescribed medications according to your doctor's instructions.

When Should You Seek Care?

Talk to a healthcare provider if you are at a higher risk for ketoacidosis or have symptoms like:9

• Breath that smells fruity
• Decreased or loss of consciousness
• Difficulty breathing
• Nausea or vomiting

People with diabetes and people at high risk of ketoacidosis may need to test their ketone levels as frequently as every 4-6 hours.3

Next Steps

• Discuss ketone testing needs with your healthcare provider, especially if you have risk factors like diabetes, pregnancy, or are on a keto diet.
• Use urine strips or a blood ketone meter to test your ketone levels at home if advised.
• Monitor for symptoms of ketoacidosis, such as abdominal pain and fruity-smelling breath, and seek medical advice if they occur.

Frequently Asked Questions

• What illnesses cause ketones in urine?

  DKA is often the cause of ketone build-up in urine. Other causes include:12

  • Acute or severe illness
  • Breastfeeding if you do not eat or drink enough
  • Eating disorders
  • Fasting 
  • High fever
  • Hyperthyroidism, or an overactive thyroid
  • Keto diet
  • Sodium-glucose cotransporter-2 (SGLT-2)
• What is a good ketone level?

  A good, or normal, ketone level is typically below 0.6 millimoles per liter. Keep in mind that ketone levels can increase slightly during alcohol use, exercise, fasting, and sleep.1

• How do I know if I’m in ketosis?

  You can take a ketone urine, blood, or breath test to know whether you are in ketosis. You may develop symptoms of ketosis, such as increased thirst, frequent urination, dry mouth, and fruity-smelling breath.6