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Lactate, Serum or Plasma, Substance Concentration

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of lactate in your blood, which can help show whether your body is getting enough oxygen and how well it is producing energy.

Quick summary

["A lactate measurement gives your care team a quick picture of your body's oxygen and energy balance."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
59005-9
Short code
Lactate 1M p chal SerPl-sCnc
Synonyms
Lactate 1M p chal SerPl-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Critical range
— – 4 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is Lactate?

Lactate is a substance your body makes when cells break down glucose for energy, especially when oxygen is limited. Muscles and other tissues normally produce some lactate, and the liver clears it from the bloodstream.

Why the Test Is Ordered

Your clinician may order a lactate test when there are signs of serious illness, poor oxygen delivery, or a condition called lactic acidosis. It can also be checked during or after intense exercise, or to help monitor someone who is very ill.

How the Sample Is Collected

The test is usually done on a sample of serum or plasma obtained from a routine blood draw. In urgent situations, it may be drawn from a line already placed in the body, and the sample is typically processed quickly.

What the Results Mean

The result reflects the amount of lactate in the sample at the time it was collected. Higher levels may be seen with oxygen shortage, certain illnesses, or intense activity, while normal levels suggest lactate is being handled as expected. Your clinician interprets the result together with your symptoms and other tests.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Lactate testing is clinically important because rising or persistently high lactate can signal impaired oxygen delivery or serious metabolic stress and may guide urgent treatment. A single result is interpreted in context, and trends over time often provide more information than one measurement alone.

Short name

Lactate

Frequently asked questions

Do I need to fast before a lactate test?
In most cases fasting is not required, but follow any instructions from your clinician or the laboratory, since preparation can depend on the reason the test is being done.
Can exercise affect my lactate result?
Yes. Strenuous exercise can raise lactate levels, so tell your care team if you have been exercising before the sample is collected.
Does a high lactate always mean something serious?
Not always. Lactate can rise with intense activity or other temporary factors, so results are interpreted along with your symptoms and other tests rather than on their own.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy