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. Small amounts circulate in the blood as part of normal cell turnover. When cells across the body go through their ordinary cycle, a little LDH is released, so the measurement reflects a broad, whole-body signal rather than the activity of any single organ.
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. People follow any preparation instructions their ordering clinician provides, since individual situations vary. Because LDH is so general, a clinician reads it in the company of symptoms, history, and other markers, using it as one input among several rather than a stand-alone answer.
Who commonly orders it
People often see LDH ordered when a clinician wants a broad marker to add to a larger evaluation. Its very generality is what makes it useful in some settings and limited in others: a wide-ranging signal can flag that something is worth exploring, but it does not, on its own, point to a particular tissue. Someone being evaluated for unexplained tiredness, or being followed over time within a broader workup, may encounter LDH as part of that picture. A clinician places the result in context and decides whether more specific testing would help clarify what the marker is reflecting.
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.
What to expect at your visit
No appointment is needed. People can walk into a patient service center during open hours, and the draw itself is quick — a phlebotomist collects a small sample from a vein in the arm, and most visits wrap up in a few minutes. Once the laboratory completes its analysis, results are posted to the account, where they can be reviewed and shared with a clinician.
Your results
Results will be emailed securely to you as a PDF.
One-time price · physician order included · no insurance needed
Prefer a fuller panel?
A curated bundle groups this test with the markers clinicians most often review alongside it — often better value than single tests.
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 appointment or referral is needed, and insurance is never involved.