Ketones are substances produced by the body when it breaks down fats for energy (metabolism). Normally, the body obtains energy from sugars (carbohydrates), but if a person's diet does not include enough sugars to supply the body with energy, or if the body cannot use sugars properly, it will break down stored fat and produce ketones (a process called ketogenesis).

If large amounts of ketones accumulate in the blood, a condition called ketosis may appear. Ketosis occurs most often in people who have poorly controlled type 1 diabetes. In type 1 diabetes, the body lacks insulin to use sugars properly. To obtain energy from sugars, people with type 1 diabetes must inject insulin so their bodies can obtain energy the normal way, from sugars. If a person with diabetes does not take enough insulin, his or her body will have to break down fat for energy.

Ketosis can also occur in people who do not eat enough sugars (carbohydrates) or in people who are severely malnourished.

Ketones can be measured in blood or in urine. Home tests to measure ketones in the urine (such as the Chemstrip K test) can be purchased at many pharmacies.

Ketones
Results

Normally there are no ketones in blood or urine.

Greater than normal values may mean

• Ketones in the urine can prove to poorly controlled diabetes.
• Ketones in the urine can also show a very low carbohydrate diet, starvation (including disorders that result in poor nutrition such as anorexia nervosa or bulimia), alcoholism, or poisoning from drinking rubbing alcohol (isopropanol).
• Ketones are often found in the urine of a person who has not eaten (fasts) for 18 hours or longer. This may occur when a person is sick and does not eat or has nausea and/or vomiting for an extended period.
• Sometimes low levels of ketones are found in the urine of a healthy pregnant woman.