Lactate
Metabolic product formed when cells make energy without enough oxygen
Also known as
Definition
Lactate, also called lactic acid, is formed mainly in muscles and red blood cells when cells make energy without enough oxygen. The liver and kidneys turn lactate back into glucose. During physical exertion the level rises briefly and usually falls quickly once the effort stops. The clinical lactate blood test is used mainly to detect lactic acidosis and assess how severe it is.
| Parameter | Value |
|---|---|
| Unit | mmol/L (mg/dL) |
| Reference Range | Adults: typically 0.5–2.2 mmol/L (4.5–19.8 mg/dL). Labs may differ; the reference range in your own report is what counts. Discuss your results with your doctor. |
Agree on your personal target range with your doctor.
1 mmol/L equals about 9.0 mg/dL (molar mass of lactic acid: 90.08 g/mol).
↓ What a low value means
MedlinePlus does not list typical associations for low lactate levels in the blood; when measured in cerebrospinal fluid (CSF), low levels are described as rare and not a medical concern. Lactate testing focuses on high values. If your value is below your lab's reference range, discuss it with your doctor.
↑ What a high value means
A high value can mean hyperlactatemia or lactic acidosis. Possible associations include conditions that reduce oxygen delivery to cells, such as shock, heart failure, lung disease, anemia, severe infection and sepsis, as well as liver and kidney disease, uncontrolled diabetes, certain medicines and very long, intense exertion such as a marathon. Clenching your fist or a tourniquet left on for a long time during the blood draw can also raise the value. The test only shows that lactate is high, not the cause; interpretation is up to your doctor.
When to test
The test is usually ordered when symptoms may point to lactic acidosis, such as shortness of breath, nausea and vomiting, muscle weakness, sweating or abdominal pain, and also to check oxygen delivery to cells or to clarify excess acid in the blood. Avoid exercise for several hours before the blood draw; your practice will tell you whether you need to fast. Do not clench your fist during the draw.
Frequently asked questions
Is a lactate value from a sports performance test comparable to the lab value? +
Not directly. During physical exertion lactate rises briefly and usually falls quickly once the effort ends. For a lab blood draw it is therefore recommended to avoid exercise for several hours beforehand. Values measured during an exercise test answer a different question than the reference range in your lab report.
Can the blood draw itself distort the value? +
Yes. If you clench your fist during the draw or the tourniquet stays on for a long time, lactate can rise without any underlying disease. Exercise in the hours before the draw can also raise the value temporarily.
Can medicines affect the lactate value? +
Yes. According to MedlinePlus, metformin, aspirin, certain HIV medicines (NRTIs) and certain airway-widening beta-agonists such as albuterol (salbutamol) can raise lactate, among others. Do not stop any medicine on your own; talk to your doctor.
What is the difference between hyperlactatemia and lactic acidosis? +
In hyperlactatemia, lactate is mildly or moderately high, but the pH of the blood is still within the normal range. In lactic acidosis, lactate is high enough to make the blood too acidic; it is more serious and needs medical treatment right away. If lactate keeps building up, hyperlactatemia can turn into lactic acidosis.
Lactate
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.