Definition of Ketonuria
< b>Ketonuria: A condition in which abnormally high amounts of ketone 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.
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 body, 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
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
type 2 diabetics. 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.
Derivation
"Ketonuria" is derived from the Greek words "keton" (acetone) and "ouron" (urine).
Related words include "ketogenesis" (production of ketone bodies), "ketosis" or
"ketonemia" (the presence of ketone bodies in the blood) and "ketotic" (adjective
describing conditions involving ketone bodies).
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