Lactate Test

This test measures the level of lactate, also called lactic acid, in a sample of your blood. In certain cases, cerebrospinal fluid (CSF) may be used. Normally, you have low levels of lactate in your blood and CSF.

High levels of lactate may be a sign of a wide variety of medical conditions. Lactate is mostly made in your muscles and red blood cells when they break down food for energy. Most of the time, your cells use oxygen to break down food for energy.

But if your cells can't get enough oxygen, they can switch to another process for making energy that doesn't use oxygen. This backup process makes lactate. Your liver and kidneys turn the lactate into glucose (sugar) that your cells use for energy.

It's normal to have brief increases in lactate when you're exercising or doing other hard physical work. That's because your body uses more oxygen when you're physically active, which triggers your cells to make energy without oxygen. Usually, your lactate levels decrease quickly when you stop the activity.

But certain medical conditions can cause a harmful buildup of lactate. If lactate levels get too high, your blood becomes too acidic. This can lead to serious health problems and a life-threatening condition called lactic acidosis.

Many types of conditions can cause lactate buildup. They fall into two main groups: Conditions that reduce the amount of oxygen that gets to your cells. These are conditions that: Affect your breathing; Reduce the flow of oxygen-rich blood in your body; Examples include: Shock; Heart failure; Lung diseases; Anemia; Severe infection and sepsis; ; Conditions that affect how much oxygen your body uses and disorders that affect how your body makes energy or gets rid of extra lactate.

Examples include: Liver and kidney diseases; Diabetes that isn't controlled; Leukemia; Mitochondrial disorders that you inherit; Using certain medicines or being exposed to certain toxins (poisons); Very strenuous exercise for a long time, such as running a marathon; ; A lactic acid test can help find high levels of lactic acid before they cause serious health problems But the test cannot diagnose the cause.

Why this test is done

You may need a lactate test:

• If you have symptoms of lactic acidosis, such as:
• Shortness of breath
• Nausea and vomiting
• Muscle weakness
• Sweating
• Abdominal (belly) pain
• To find out if your cells are getting enough oxygen
• To find out why you have too much acid in your blood

You may also need this test if your health care provider thinks you have signs and symptoms of any of the many conditions that can cause lactic acidosis.

If you have been diagnosed with high levels of lactate, you may need to have repeated tests to monitor your condition.

If you have symptoms of meningitis, you may need to have your lactate levels measured in your blood and your cerebrospinal fluid. Symptoms of meningitis include:

• Severe headache
• Fever
• Stiff neck
• Sensitivity to light

How to prepare

Your provider will tell you how to prepare for your test. Your provider may tell you to:

• Avoid exercise for several hours before the test. That's because exercise can cause a temporary increase in lactate levels.
• Fast (not eat or drink) for 8 to 10 hours before the test.

You may need to stop taking certain medicines before this test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.

Sample type

Blood CSF

Other names for this test

lactic acid test, lactic acid: plasma, L-lactate