Lactate Dehydrogenase (LDH) Test
A lactate dehydrogenase, or LDH, test measures an enzyme that is present in many tissues throughout the body. Because it is so widespread, clinicians often use it as a general marker that is interpreted alongside other information rather than on its own.
About this test
Lactate dehydrogenase is an enzyme involved in the way cells turn nutrients into energy. It is found in nearly every tissue, including the liver, heart, muscle, kidneys, and blood cells.
The test is done with a simple blood draw at a patient service center. A phlebotomist collects a sample from a vein, usually in the arm, and sends it to the laboratory.
Who might consider this test?
- People often see LDH ordered when a clinician wants a broad marker to add to a larger evaluation.
- Someone being evaluated for unexplained tiredness
Test details
| Quest code | 593 |
|---|---|
| Methodology | Spectrophotometry |
| Sample type | 1 mL serum |
| Collection | Quest patient service center |
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Additional details
What this test looks at
The LDH result reflects the amount of lactate dehydrogenase circulating in the blood, gathered from its many tissue sources. Because the enzyme lives in so many places, the measurement is best understood as a general marker of cell activity and turnover rather than a readout for one organ. That breadth is exactly why a clinician often pairs it with more specific tests when a particular question comes into focus.
It helps to keep the whole-body nature of LDH in mind. A single figure blends contributions from muscle, liver, blood cells, and more, so a clinician uses surrounding context to interpret what the marker may be signaling.
How it's often used alongside other tests
LDH is frequently read as part of a broader set of markers rather than in isolation. Depending on the question, it may sit alongside a liver panel, a complete blood count, or other enzymes, and its general nature means a clinician usually looks to more targeted tests to pinpoint a source. Read together, these results give a clinician a fuller and more specific view than LDH can provide alone.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does an LDH test measure?
It measures lactate dehydrogenase, an enzyme found in many tissues throughout the body. The result reflects a broad, whole-body signal rather than the activity of one organ.
Why is LDH called a general marker?
Because the enzyme is present in nearly every tissue, its measurement blends many sources. That makes it useful as a wide-ranging signal but limited for pointing to a specific organ.
Why might someone consider this test?
Clinicians often order LDH as one broad input within a larger evaluation, then look to more specific tests when a particular question needs clarifying.
How is the sample collected?
Through a routine blood draw at a patient service center. A phlebotomist takes a small sample from a vein in the arm and sends it to the laboratory.
Do I need to fast before an LDH test?
Preparation varies. LDH is sometimes drawn within a larger panel that may call for fasting, so people should follow whatever instructions their ordering clinician provides.
Can I get the Lactate Dehydrogenase test without a doctor's visit or insurance?
Yes. The $29 cash price includes an independent physician's order, so no referral is needed, and insurance is never involved.