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Lactate test

Also called: Lactic acid

A lactate test measures lactic acid in the blood. High levels can be a sign of sepsis, shock, or not enough oxygen reaching tissues.

SampleA small tube of blood from a vein in your arm
Fasting?Usually not needed
ResultsWithin minutes to hours
Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.

What the test is

It's usually done in the emergency room or hospital.

Why it's done

  • Possible sepsis or shock
  • Severe illness or heavy breathing without a clear cause
  • Metformin users who are very sick

Getting ready and what happens

  • Done urgently; no preparation.

How the test is done

  • A health worker cleans the skin, puts a band around your arm, and draws blood from a vein with a small needle. It takes a few minutes.

What the results mean

ResultTypical range for adults
LactateBelow about 2 mmol/L

Normal ranges vary from lab to lab and can differ by age, sex, and pregnancy. Your report lists your lab's own range next to each result. A result a little outside the range is often not a problem.

High

Over 2 raises concern, and over 4 is a warning sign of severe illness, especially with infection.

Questions to ask your provider

  • What do my results mean for me?
  • Do I need to repeat this test or have other tests?

Risks

A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.

Related conditions

Related medicines

Related tests

Sources

Last updated 2026-11-13.