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Ketones blood test

A serum ketone test measures how many ketones are there in the blood.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

No preparation is needed.

How the Test will Feel

When the needle is inserted to draw blood, some people feel slight pain. Others feel a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

Ketones are substances produced in the liver when fat cells break down in the blood. This test is used to diagnose ketoacidosis. This is a life-threatening problem that affects people who:

  • Have diabetes. It occurs when the body cannot use sugar (glucose) as a fuel source because there is no insulin or not enough insulin. Fat is used for fuel instead. When fat breaks down, waste products called ketones build up in the body.
  • Drink large amounts of alcohol.

Normal Results

A normal test result is negative. This means there are no ketones in the blood.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

A test result is positive if ketones are found in the blood. This may indicate:

A diet low in carbohydrates can increase ketones.


Veins and arteries vary in size from one patient to another and from one side of the body to the other. Drawing blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

  • Excessive bleeding
  • Fainting or feeling lightheaded
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

Alternative Names

Acetone bodies; Ketones - serum; Nitroprusside test; Ketone bodies - serum; Ketones - blood



Ghosh S, Collier A. Acute metabolic complications. In: Ghosh S, Collier A. Churchill's Pocketbook of Diabetes. 2nd ed. Philadelphia, PA: Elsevier; 2012:chap 4.

Khan MI, Weinstock RS. Carbohydrates. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 16.

Update Date 1/31/2015