Lactate Test
Reviewed
This test measures the level of lactate (lactic acid) in your blood or cerebrospinal fluid. High levels can indicate a harmful buildup that may lead to a serious condition called lactic acidosis. The test helps detect high lactate levels early but cannot diagnose the cause.
Preparation and collection
Your provider will give you specific instructions. You may be told to avoid exercise for several hours before the test and to fast (not eat or drink) for 8 to 10 hours. Tell your provider about all medicines you take, as some may need to be stopped temporarily. Do not stop any medicine unless your provider tells you to.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- The test can only show whether lactate levels are abnormal; it cannot diagnose the cause of the abnormality.
- Temporary increases in lactate can occur with exercise or hard physical work, so preparation instructions must be followed to avoid false elevations.
- Clenching your fist during blood collection can temporarily raise lactate levels.
- Certain medicines (e.g., metformin, aspirin, some HIV treatments) may cause high lactate levels, which could affect interpretation.
- Results from a blood sample taken from an artery may be more accurate than from a vein, but the test still cannot identify the underlying condition.
What to do next
If you have questions about your results, talk with your provider. Your provider will consider your symptoms, medical history, and the results of other tests to diagnose the cause of abnormal lactate levels and recommend appropriate treatment.