Finding the right tests…
Emergency services available 24 x 7
Emergency services available 24 x 7
Finding the right tests…
Biochemistry
LDH is an enzyme found in almost every tissue in your body — heart, liver, kidney, muscle, brain, blood cells, and lungs — which makes it a broad flag for cell damage rather than a marker for any one organ. A raised LDH tells your doctor that cells somewhere are breaking down faster than usual, but it can't say where on its own, so it's read alongside more specific tests once it's high. It's used to help investigate anemia caused by red blood cell breakdown, monitor certain cancers such as leukemia and lymphoma, and check for tissue damage after an injury or illness. MedlinePlus gives 125 to 220 IU/L as a typical adult range, though this varies by lab.
This test measures the total amount of lactate dehydrogenase circulating in your blood, an enzyme your cells use to help produce energy. Because LDH sits inside so many different cell types, the test can't distinguish which organ it's coming from — it only shows that cell turnover or damage somewhere is higher than expected. A raised result is a prompt for more specific follow-up tests, not an answer by itself.
LDH being present in nearly every tissue is what makes this test useful as a broad screen and also what limits it. A high result confirms that cells are breaking down somewhere in the body, but pinning down where needs other, more targeted tests.
Doctors order LDH to help evaluate anemia where red blood cells are breaking down faster than normal, to monitor blood cancers such as leukemia and lymphoma, and to check for tissue injury following events like a heart attack, muscle damage, or liver disease. It can also rise with lung conditions and infections such as infectious mononucleosis.
When a raised LDH needs more explanation, a separate LDH isoenzymes test can break the total number down into five distinct forms, each concentrated in different tissues, which helps narrow down where the damage is coming from. This is a different, more detailed test from the total LDH measurement.
MedlinePlus lists a typical adult range of 125 to 220 IU/L, though it notes that normal ranges vary somewhat between labs depending on the method used. Your doctor reads your result against the range printed on your own report, alongside your symptoms and any other tests ordered at the same time.
MedlinePlus lists a typical adult range of 125 to 220 IU/L, though normal ranges vary between labs depending on the method used. Use the range printed on your own report.
A raised LDH shows that cells somewhere in the body are breaking down faster than usual, which can happen with anemia, certain cancers, liver disease, muscle injury, or infections such as infectious mononucleosis. It doesn't identify the exact cause on its own.
Not by itself. Because LDH is present in nearly every tissue, a raised total level is a general signal rather than a location. Your doctor may order an LDH isoenzymes test or other organ-specific tests to narrow it down.
LDH can rise with certain cancers, including leukemia and lymphoma, so doctors sometimes use it to help monitor how a cancer or its treatment is progressing over time. It's used alongside other markers, not as a stand-alone measure.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Low LDH is uncommon and isn't usually a cause for concern on its own. Your doctor would look at it in context if it came with other unexplained findings.
Requirements can vary by lab, especially if it's combined with other blood tests. Ask your doctor or the centre what's needed before your appointment.