Test Overview
A ketone test
checks for
ketones in your blood or urine. Ketones are substances
that are made when the body breaks down fat for energy. Normally, your body
gets the energy it needs from
carbohydrate in your diet. But stored fat is
broken down and ketones are made if your diet does not contain enough
carbohydrate to supply the body with sugar (glucose) for energy or if your body
can't use blood sugar (glucose) properly.
Some home blood sugar
meters can also measure ketone levels in the blood. Home
urine tests to measure ketones are available.
Why It Is Done
A blood test is the most accurate method
of measuring ketones. It is recommended for all people with
diabetes whenever symptoms of illness are present,
such as nausea, vomiting, or abdominal pain. These symptoms often happen with high blood sugar and may mean you have
diabetic ketoacidosis, a potentially life-threatening
condition.
A urine test is the most commonly used method of
measuring ketones. But it is less accurate than a blood test. A urine test may be done
to:
- Monitor a person who has diabetes, especially when that person is sick.
- Monitor a person on a low-carbohydrate
diet and/or high-fat diet.
- Monitor a person who is not able to eat due to anorexia or fasting, who is vomiting a lot, and/or has diarrhea.
- Monitor a person who is sick.
- Monitor a pregnant woman who has diabetes or has developed
gestational diabetes.
How To Prepare
No special preparation is needed before
having this test.
Talk to your doctor about any
concerns you have regarding the need for the test, its risks, how it will be
done, or what the results will mean. To help you understand the importance
of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
Blood test
The health professional taking a sample
of your blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- Apply a gauze pad or cotton ball over the needle site as
the needle is removed.
- Apply pressure to the site and then a
bandage.
Urine test
- Collect a urine sample in a clean
container.
- Follow the manufacturer's directions on the bottle of
test strips or tablets.
- Avoid getting toilet paper, pubic hair,
stool, menstrual blood, or other foreign matter in the urine sample.
How It Feels
Blood test
The blood sample is taken from a vein
in your arm. An elastic band is wrapped around your upper arm. It may feel
tight. You may feel nothing at all from the needle, or you may feel a quick
sting or pinch.
Urine test
There is normally no discomfort
involved with collecting a urine sample.
Risks
Blood test
There is very little risk of a problem
from having blood drawn from a vein.
- You may develop a small bruise at the
puncture site. You can reduce the risk of bruising by keeping pressure on the
site for several minutes after the needle is withdrawn.
- In rare
cases, the vein may become inflamed after the blood sample is taken. This
condition is called phlebitis and is usually treated with a warm compress
applied several times daily.
- Continued bleeding can be a problem
for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other
blood-thinning medicines can also make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your health professional before your blood is drawn.
Urine test
There are no risks associated with
collecting a urine sample.
Results
A ketone test checks for substances made
when the body breaks down fat for energy (ketones).
KetonesNormal: | There are no ketones in your blood or
urine. |
|---|
Abnormal: | Ketones are present in your blood or
urine. |
|---|
Urine test
If either the test strip or the urine
changes color when the tablet is dropped into the sample, ketones are present
in your urine sample. The test results are read as negative to 1+ to 4+ or
small to large.
High values
You may have ketones in your urine if
you:
- Have poorly controlled diabetes or
diabetic ketoacidosis.
- Are on a very
low-carbohydrate or high-fat diet.
- Are
starving or have an eating disorder, including disorders that result in poor
nutrition such as
anorexia nervosa or
bulimia, alcoholism, or poisoning from drinking
rubbing alcohol (isopropanol).
- Have not eaten (fasted) for 18 hours
or longer.
- Are pregnant. But a moderate amount of ketones in a
pregnant woman may harm the fetus and may be an indication of gestational
diabetes.
The level of ketones, and not just the presence of
ketones, may be important to your doctor as well. Many conditions can change
ketone levels. Fasting usually causes only mild increases in the level, but
ketone levels in diabetic ketoacidosis are much higher. Your doctor will discuss any significant abnormal results with you in relation
to your symptoms and past health.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Taking medicines, such as:
- Levodopa, such as Sinemet or Larodopa.
- Phenazopyridine, such as Pyridium or Uristat.
- Valproate,
such as Depakote, Depacon, or Depakene.
- Vitamin C (ascorbic acid),
when taken in large amounts.
- Waiting a long time after collecting the urine to test it.
What To Think About
Your doctor may recommend you test for ketones if you have
diabetes and you have any of the following conditions:
- Your blood sugar level is 300 mg/dL (16.7
mmol/L) or higher, especially if your level has been high for many hours.
- You are pregnant.
- You are sick or
feeling very stressed.
- You have
symptoms of diabetic ketoacidosis.
References
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Credits
| By | Healthwise Staff |
|---|
| Primary Medical Reviewer | E. Gregory Thompson, MD - Internal Medicine |
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| Specialist Medical Reviewer | Alan C. Dalkin, MD - Endocrinology |
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| Last Revised | July 5, 2011 |
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