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Lactic acid test

Definition

Lactic acid is mainly produced in muscle cells and red blood cells. It forms when the body breaks down carbohydrates to use for energy during times of low oxygen levels. Your body's oxygen level might drop during intense exercise or if you have an infection or disease.

A test can be done to measure the amount of lactic acid in the blood.

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Alternative Names

Lactate test

How the test is performed

A blood sample is needed. for information on how this is done, see: Venipuncture.

How to prepare for the test

Do not exercise for several hours before the test. Exercise can cause a temporary increase in lactic acid levels.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

This test is usually done to diagnose lactic acidosis.

Normal Values

4.5 to 19.8 mg/dL (0.5-2.2 mmol/L)

Note: mg/dL = milligrams per deciliter; mmol/L = millimoles per liter

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean

Abnormal results mean that body tissues are not getting enough oxygen. See: Oxygen deprivation

Conditions that can increase lactic acid levels include:

Heart failure
Liver problems
Lung disease
Not enough blood containing oxygen getting to a certain area of the body
Severe infection that affects the entire body (sepsis)
Very low levels of oxygen in the blood

What the risks are

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

Risks may include:

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

Special considerations

Clenching the fist or having the elastic band in place for a long time while having blood drawn can artificially increase lactic acid level.

References

DuBose TD Jr. Disorders of acid-base balance. In: Brenner BM, ed. Brenner and Rector's The Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier;2008:chap 14.

Seifter JL. Acid-base disorders. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 119.

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