What are ketones
Ketones are naturally occurring fatty acids produced in the body. There are three ketone bodies, known as acetone, aceo-acetone, and beta-hydroxybutyrate (important to diabetes; see below), which are produced from fat and certain amino acids. An excessive amount of ketones is also often produced by the body during an uncontrolled diabetic event (see DKA, below).
Why does the body need ketones?
The body cannot store glucose for more than 24 hours, which is why it is important to maintain glucose levels for energy. And of course, this is also why humans must consume various foods to maintain the levels. In particular, the human brain (and other cells in the body) functions with the help of glucose and ketones. If there is not sufficient glucose, then the liver takes fat and certain amino acids (called fatty-acid metabolism) and turns them into ketones, first to feed the brain, then the rest of the body. This is called keto-adaptation, or nutritional ketosis, and is thought to be an evolutionary adaptation.
How are ketones measured?
Ketones are normally produced by the liver. They will be completely metabolized so there will be few, if any, that appear in a person’s urine. Normally, 3 to 15 milligrams of ketones (a very small amount) are excreted in the urine daily. Increased amounts of ketones, usually determined from a ketone urine test, can mean several conditions, many of which resemble other health problems. These conditions can include:
- Poorly controlled diabetes
- Diabetic ketoacidosis (see below)
- Starvation (for example, not eating for long periods, usually 12 to 18 hours, or anorexia nervosa, bulimia nervosa, alcoholism, or fasting)
- Some metabolic disorders
- A too-high protein or low-carbohydrate diet
- Vomiting over a long period
- A hyperactive thyroid gland (meaning too much thyroid hormone)
- Some types of toxic poisoning
How are ketone levels interpreted by physicians?
Physicians interpret ketone levels mainly on the basis of ketone urine tests. These may include test kits purchased at a drug store (they contain “dipsticks” coated with chemicals that react to ketone bodies by changing color) or sending a urine sample to a laboratory to be analyzed, usually a physician’s choice to obtain a more accurate reading. (There are also blood glucose meters that can measure blood ketones; for more information about meters, see the chapter “Taking Charge of Diabetes.”) The results are interpreted as follows (most often, abnormal results mean more tests must be made to determine the cause of the excess in ketones):
- A negative test result is normal, with a small amount of ketones in the urine.
- An abnormal result means there are ketones in the urine; results are broken down this way:
- small—less than 20 milligrams per deciliter
- moderate—30 to 40 milligrams per deciliter
- large—greater than 80 milligrams per deciliter
Ketone tests can produce false results. For example, there may be a false-positive test result but no indication of ketones upon further testing. This may indicate certain conditions, mainly dehydration or the result of taking particular medications (for example, phenazopyrazine or vitamin C). There can also be false-negative ketone results, usually with urine-testing kits.
Is there a treatment if a person with diabetes tests positive for ketones?
Yes, if a person with diabetes tests positive for ketones when using a meter that detects ketone bodies, he or she should contact their diabetes educator or physician. The elevated numbers may mean the person needs additional insulin. According to the Joslin Diabetes Center, the person should also drink plenty of water and other fluids (that contain no calories) in order to flush out the ketones from the blood. The person is also advised to continue checking blood glucose levels for three to four hours, testing for ketones if the blood glucose level is over 250 mg/dl (milligrams per deciliter). In addition, a person with a blood glucose level over 250 mg/dl and ketones present should not exercise. There is a good reason: If both blood glucose and ketone levels are high, it can lead to a life-threatening condition called diabetic ketoacidosis (see below).
What is diabetic ketoacidosis, also known as DKA?
Diabetic ketoacidosis can occur when a person with diabetes has an episode of extremely high blood glucose and elevated levels of ketone (called positive ketones). It is not common and is most often associated with type 1 diabetes. (People with type 2 diabetes can also experience DKA, especially if they have very late-stage, insulin-dependent diabetes. But DKA is rarer in people with type 2 diabetes than in those with type 1.) It is most often detected with a urine test, as the ketones spill out into the urine. It is also often identified with a ketone test if the physician suspects an overabundance of ketones in the blood.
What happens if a person with diabetes develops diabetic ketoacidosis?
Diabetic ketoacidosis (DKA) occurs when a person with diabetes does not receive enough insulin. Without the insulin to help get the glucose into the body’s cells, the person essentially goes into what can be called a “starvation mode.” This triggers the liver to start making ketones out of fat and proteins to give the body’s cells energy, especially in the brain. But because there is no insulin, the cycle continues, and more ketones are produced. Both glucose and ketones are then transferred to the urine. The kidneys begin emptying the bloodstream of excess glucose and ketones with water, causing the person to urinate more and become dehydrated. By the time ketones—especially beta-hydroxybutyrate (75 percent) and to a lesser extent aceto-acetate—reach around 15 to 25 mM (millimolars), the body’s resulting pH balance (for more about pH, see this chapter) leads to metabolic problems, and the person becomes very ill. The metabolic disturbance usually causes low blood pressure and shock, and if not treated, the process can lead to a coma and eventual death.
Why are diabetic ketoacidosis and nutritional ketosis often confused?
The body normally produces some small amount of ketones every day. In nutritional ketosis, the body produces ketones when it burns fat for energy or fuel, occurring, for example, when a person loses weight or fasts. This is when the liver metabolizes fatty acids, turning them into ketones that are used as energy in various parts of the body. But diabetics must be careful not to confuse normal ketosis with diabetic ketoacidosis—the first is usually something to be watched, while diabetic ketoacidosis is most often a medical emergency. In a person with diabetes, diabetic ketoacidosis means the blood glucose levels are high (hyperglycemia), the person has low insulin levels, and there are moderate to large amounts of ketones in the blood.
Historically, was it often recorded how diabetes affected a person?
Yes, before the reasons and treatments for diabetes were better known, doctors watched their patients with diabetes go through a great deal of suffering. And although they did not know the details about diabetes—or even how ketones worked in a person with diabetes—many physicians’ reports detailed the stages toward death. In the early twentieth century that meant most often people with type 1 diabetes.
It is now known that often one of the major reasons that caused a person to die from diabetes (usually type 1) was the body’s buildup of ketone bodies. As the diabetic person’s body slowed down metabolizing food, it used fatty acids for its energy. This led to a buildup of ketones, and over time, the chemical clogged the person’s bloodstream and passed out in the urine. The person with an overabundance of ketones in his or her system would breathe out what was often called a “sickly apple smell” and continued to decline in health. As the ketones continued to accumulate, the body’s pH (see below) dropped to dangerous acidic levels—what we now know as diabetic ketoacidosis. As the person sank into a deep coma, death was usually only a few hours away.
Who should be aware of developing diabetic ketoacidosis?
People with type 1 diabetes, and insulin-dependent type 2, should be aware of their ketone levels (or symptoms of such a problem) so they do not develop diabetic ketoacidosis. Many physicians suggest monitoring ketones in all people with diabetes, especially in the following circumstances: if the person with diabetes misses an insulin injection or uses too little insulin during a period of illness or excessive or unusual stress; if the person’s diet is low in carbohydrates, the person is exercising a great deal, or a combination of both; in pregnant women who have diabetes, or gestational diabetes; and when the person’s blood glucose is high, or, if the person monitors ketones, if that level is very high.
Is there a treatment for diabetic ketoacidosis?
For people who develop a more advanced case of diabetic ketoacidosis and get to a hospital for help, there are other more extensive treatments available. Commonly, the condition is treated with an intravenous infusion of fluids and insulin in order to rehydrate the person. This treatment also lowers the person’s blood glucose levels and reverses the acidosis in the blood and body tissues. This is all done gradually to prevent the chance of hypoglycemia (low blood glucose levels) and hypokalemia (low potassium levels). Although measures are taken to help a person who develops diabetic ketoacidosis, it is estimated that almost 1,900 people with diabetes die each year from this condition.
Can a person with diabetes keep track of ketones in his or her blood?
Yes, it is possible for a person with diabetes to keep track of the ketone levels in the blood. Along with being checked by a hospital or the person’s physician, a person can use home blood tests and even some glucometers that detect the presence of ketones.