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Immunology & Autoimmune
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This test measures the amount of lactate in a blood sample collected for a blood gas analysis. Lactate is a substance made when your cells turn nutrients into energy, and it tends to rise when oxygen delivery is limited or when your body’s metabolism is highly active.
A mixed sample means the blood is not strictly arterial or venous. It is often drawn from a central line or another source that reflects several parts of the circulation. Clinicians use this test in emergency and intensive care settings, and in other situations where they need a quick picture of how well your body is using oxygen.
Lactate helps your care team understand how well your tissues are getting oxygen and whether your body is under metabolic stress. Levels can rise with serious infections, circulation problems, heart or lung conditions, seizures, severe asthma, or after major injury or surgery. Certain medications and conditions that affect the liver or kidneys can also influence lactate. Your clinician may order this test to evaluate sudden illness, guide treatment, or track recovery over time.
Trends are often more informative than a single result. When you are being treated for problems like infection or poor circulation, repeating this test helps assess whether treatment is improving blood flow and oxygen delivery.
Your lactate level is interpreted alongside your symptoms, vital signs, and other test results, especially the blood gas values. A higher result can signal that your body is stressed or not getting enough oxygen, but it does not identify a single cause on its own. A result that decreases with treatment usually suggests improvement.
If your value is higher than expected, your clinician may look for causes such as dehydration, low blood pressure, breathing problems, or tissue injury, and may adjust fluids, oxygen, medications, or other treatments. If you feel well and the result is only slightly above what is expected, your clinician may simply repeat the test and review recent activity or medicines.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Hard exercise, shivering, or seizures can temporarily raise lactate by increasing muscle metabolism. Let your care team know about any recent exertion or events before the draw.
Prolonged tourniquet time, repeated fist clenching, delayed transport, or not chilling the sample can falsely elevate lactate. Proper collection and prompt processing reduce this risk.
Drugs such as epinephrine, albuterol, metformin, linezolid, and antiretrovirals can affect lactate. Drawing from or near an IV line, especially one infusing additives, may contaminate the sample.
Lactate is cleared by the liver and kidneys. Conditions that impair these organs can lead to higher levels independent of oxygen delivery.
Low blood pressure, severe infections, heart or lung problems, or significant blood loss can reduce oxygen delivery to tissues and raise lactate.
During labor, immediately after intense exertion, or following major surgery, lactate may be transiently higher. Repeating the test after stabilization often clarifies the picture.
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