What Are Ketones?

Author: Judy Kohn, RN, BSN, CDE

Last Updated: Thursday, November 15, 2007

Q: "What are ketones?"

A: Ketones are a by-product/or waste product when your body burns stored fat for energy. Ketones can be measured in the urine with a visually read strip, and in the blood by using the Precision Xtra® meter. Before I describe various situations in which a person might have ketones, let me provide a simple review of how the body works:

• The foods you eat break down into glucose (sugar). Glucose travels in the blood and into your cells. Insulin is a hormone (or "key") that "unlocks the doors of your cells" to allow glucose to enter your cells where it can be turned into energy. So without insulin, glucose wouldn't be able to get into the cells.
• Your brain (and the rest of your body) requires glucose to function. When you haven't eaten for a while, or during the night when you're asleep, your liver releases stored glucose to keep you supplied with energy.
• If you don't eat for several days, the stored glucose in the liver is depleted, and your body is in a starvation state. In this situation, the body will break down stored fat to get energy, (and ketones can show in the urine, indicating that fat was burned) and also the body will create sugar out of other substances in the body in order to supply the brain with glucose.

So if you keep in mind that fat burns when there isn't available glucose (that is, when the body is starving) and ketones indicate that fat was burned, then the following situations will be easier to understand.

Situations where you could have ketones:

• A non-diabetic can show ketones if he/she hasn't eaten for several days, or is on a severe weight reduction diet. In this situation the body is starving, and there isn't enough available glucose, so fat will burn for energy and the by-product, ketones, may show in the urine or blood.
• Pregnancy: During pregnancy, you are eating for two. If you aren't eating enough, your body will burn fat to get more energy. In gestational diabetes (temporary diabetes during pregnancy) and in pregnancy with pre-existing diabetes, women are advised to check ketones each morning. If the blood glucose is normal but there are ketones present, usually the mother will be advised to increase her bedtime snack (but you should first check with your healthcare professional).
• Hypoglycemia if you are taking diabetes medication: When no glucose is available, your body is in a starvation state and will break down stored fat to get energy. It is not necessary to check ketones during hypoglycemia and these ketones are harmless. When the blood glucose is low, it is most important to immediately correct it with proper treatment of a fast-acting sugar such as glucose tabs, fruit juice or a regular soft drink.
• High blood glucose: High blood glucose means you don't have enough insulin to allow the glucose to get into the cells, so the glucose is piling up in the blood and/or being excreted in the urine. Your body needs insulin to use glucose for energy. So if you don't have enough insulin, your body will start to burn fat for energy.
• Insulin pump malfunction or dislodged pump set: Insulin pumps provide a continuous delivery of background insulin. If the supply is disrupted due to a pump problem or a clogged/dislodged pump set, then no insulin would be available and, as noted above under "high blood glucose," you will start to burn fat for energy. Insulin pump users are trained to check ketones and to check the pump connections anytime there is unexplained high blood glucose, for the ketones may indicate a pump malfunction.
• Illness/stress: When you are under physical or emotional stress, your body needs extra energy to fight it. Hormones are triggered, which tell the body to release stored glucose in an attempt to give you more energy. If you don't have enough insulin to help this glucose get into your cells, your body will again burn fat for energy.
• Exercise: Exercise requires extra energy. If you haven't eaten enough or if you don't have enough insulin available to allow the glucose to get into the cells, again the cells are starving and will turn to fat for energy.

When ketones are a concern with high blood glucose:

If you don't have enough insulin available in your body, and the blood glucose rises, your body will eliminate the glucose by passing it into your urine. As your body takes fluid from everywhere it can to help dilute the urine and pass the sugar out, you'll get dehydrated. Because the glucose is passing out through the urine, the body is starving and fat will burn. If the body burns too much fat too quickly, ketones will accumulate in your bloodstream. Ketones make your body too acidic, which will upset the body's chemical balance. Your body might not be able to excrete the ketones adequately. In this setting, if your glucose is high, you are dehydrated, and your ketones are large, then your body's chemical balance is disrupted and you could develop a life-threatening condition called ketoacidosis. Usually only people with type 1 diabetes are at risk for this condition, but everyone should know the signs of Ketoacidosis.

Signs of Ketoacidosis:

• Increased thirst
• Increased urination
• Dry mouth
• Labored breathing
• Fruity breath
• Nausea/vomiting
• Stomach pain
• Loss of appetite
• Fatigue, drowsiness
• Dry, flushed skin or fatigue

Testing for Ketones:

• Generally you should check for ketones if you are ill, pregnant, under stress or your blood glucose is over 250 mg/dl, but first check with your healthcare professional.
• According to the ADA Clinical Practice Recommendations, blood ketone testing is now preferred over urine testing for diagnosing and monitoring ketoacidosis.
• Follow the directions provided on the package. If you show any ketones in the urine or blood, call your healthcare professional right away.

DOC09478-Rev-B 12/07