Definition of Ketonuria

Ketonuria: A condition in which abnormally high amounts of ketones and keytone bodies (a byproduct of the breakdown of cells) are present in the urine.

Ketonuria is a sign seen in diabetes mellitus that is out of control. Diabetics prone to ketonuria need to monitor their urine for signs of ketone buildup that could lead to life-threatening symptoms unless promptly treated. Ketonuria can also develop as a result of fasting, dieting, starvation and eating disorders.

Alternate names for ketonuria include ketoaciduria and acetonuria.

Digestion and the Role of Insulin

When food is digested, the body turns fats, proteins and carbohydrates into components that sustain and nurture the body. Fats are converted into fatty acids, proteins into amino acids and carbohydrates into glucose (a sugar) that enters the bloodstream. The body needs glucose as fuel to perform activities. However, glucose has to be delivered. It does not automatically route itself to body sites requiring fuel. Insulin, a hormone secreted by the pancreas, carries out this task, delivering glucose to cells throughout the body. Muscles and tissues then have the energy to do their jobs.

Ketones and Ketone Bodies: What They Are, How They Accumulate

In some people with diabetes mellitus, the pancreas releases insufficient amounts of insulin or no insulin at all. Consequently, glucose goes largely undelivered. In a desperate attempt to provide fuel, the body begins feeding on itself -- that is, it breaks down muscle and fat to burn as fuel. Ketone bodies are a byproduct of this process.

Ketone bodies consist chemically of three substances (beta-hydroxybutyric acid, acetoacetic acid, and acetone).

When ketone bodies are released, they enter the bloodstream, acidify the blood, and are eventually excreted mostly in urine. (One type of ketone body exits via the lungs.) Without treatment, glucose and ketone bodies may build to dangerous levels in the blood. Stress and illness can increase the risk of glucose and ketone buildup. When glucose and ketone bodies build to very high levels, the following conditions then exist:

1. Hyperglycemia: too much sugar in the blood.

2. Ketoacidosis: too many ketone bodies in the blood.

3. Ketonuria: accumulation of ketone bodies in the urine. When ketone is excreted, sodium is excreted along with it.

Symptoms and Treatment

Symptoms of glucose and ketone-body overload include thirst, frequent urination, dehydration, nausea, vomiting, heavy breathing, dilation of the pupils and confusion resulting from the toxic effects of ketone bodies and acid accumulation on the brain. In addition, the symptoms may also include a breath odor resembling the smell of fruit. (One type of ketone, acetone, is excreted through the lungs, causing the fruity smell.) This symptom-complex can progress to coma and death.

Treatment with insulin and intravenous fluids can restore normal levels of blood sugar and end ketoacidosis and ketonuria.


Prevention of emergencies in diabetics prone to ketonuria requires close monitoring of the levels of glucose in the blood and ketone bodies in the urine. Although ketone-body overload in the blood occurs primarily in type 1 diabetics, it can also occur in people with type 2 diabetes. Therefore, it is commonly recommended that all diabetics should closely monitor not only their glucose levels but also their ketone levels. Home tests kits are available to check both glucose and ketone levels.

Ketogenic Diet

Ironically, ketonuria is a desired effect of a special "ketogenic diet" used to prevent or reduce the number of seizures in people with epilepsy (seizure disorders). Some physicians use this diet when conventional medications fail to control seizures or when the side effects of medications become intolerable.

The ketogenic diet, which is high in fats and low in protein and carbohydrates, mimics starvation and raises the level of ketone bodies in the blood. The ketone bodies can prevent or decrease the incidence of many types of seizures, including myoclonic (spastic) and atonic (drop) seizures. They may also limit other types of seizures, including so-called staring spells. Why ketone bodies may inhibit such seizures is not known.

The ketogenic diet is very strict and must be closely managed under a physician's supervision. Only a limited number of medical centers are equipped and trained to prescribe it.

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