Lactate Dehydrogenase (LDH)
An enzyme found in almost every tissue. A higher level can be a general sign of cell or tissue damage, and it does not point to one condition.
AI-verified against cited sources. Awaiting expert reviewAlso called LDH, LDLOINC 2532-0
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What it is
Lactate dehydrogenase (LDH) is an enzyme that helps your cells make energy. It is found in almost all tissues, with the largest amounts in muscle, liver, kidney and red blood cells. When cells are damaged or break open, LDH leaks into the blood. This test measures how much LDH is in your blood. Some labs print it as LD or LDH, and it is the same test.
Why it matters
A higher LDH tells your clinician that some tissue may be injured or breaking down, but it cannot say where or why. It is usually read together with other tests. Clinicians use it when they look at red blood cell breakdown (hemolysis), liver and muscle problems, and some cancers, and to follow how a known condition or its treatment is going.
If it’s low
A low LDH is not common and is usually not considered a health problem. Large amounts of vitamin C or vitamin E can lower it, and a very rare inherited condition can cause a persistently low level.
Common causes
- Large amounts of vitamin C or vitamin E
- A rare inherited condition called lactate dehydrogenase deficiency
What can help
- Mention your vitamin C and vitamin E supplements to your clinician
- Ask whether anything needs follow-up if the result is persistently very low
If it’s high
A higher LDH means cells somewhere in the body may be releasing more of the enzyme than usual. Many things can cause this, and a mild rise is often temporary. A high result on its own does not tell you what is wrong. Your clinician will read it with your symptoms and your other results.
Common causes
- A blood sample in which red blood cells broke open during collection or handling
- Intense exercise
- Some medicines, including aspirin
- Muscle injury
- Breakdown of red blood cells (hemolytic anemia)
- Liver conditions such as hepatitis
- Infections such as infectious mononucleosis
- Heart attack, stroke or other reduced blood flow to a tissue
- Pancreatitis
- Some cancers, including lymphoma, leukemia, melanoma and testicular cancer
What can help
- Ask whether a repeat test is worth doing, especially if the sample may have been hemolyzed or you exercised hard beforehand
- Review your medicines and supplements with your clinician, including over-the-counter ones
- Ask which follow-up tests, such as an isoenzyme test, could help find where the LDH is coming from
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
The usual range depends on sex and age. Choose women or men to see the one that applies.
Children and teens 12 ranges
- Men, 1–3195–361 U/L
Source: Labcorp
- Women, 1–3192–352 U/L
Source: Labcorp
- Men, 4–6180–313 U/L
Source: Labcorp
- Women, 4–6180–311 U/L
Source: Labcorp
- Men, 7–9166–291 U/L
Source: Labcorp
- Women, 7–9166–290 U/L
Source: Labcorp
- Men, 10–12155–280 U/L
Source: Labcorp
- Women, 10–12135–260 U/L
Source: Labcorp
- Men, 13–15126–244 U/L
Source: Labcorp
- Women, 13–15118–215 U/L
Source: Labcorp
- Men, 16–17118–222 U/L
Source: Labcorp
- Women, 16–17114–209 U/L
Source: Labcorp
See LDH by age and sex, with the U.S. survey numbers where they exist.
How common is your level?
NHANES describes the US civilian, non-institutionalized population, not a 'healthy' reference group. People with disease, on medication, fasting or not (except fasting-subsample markers), smokers and so on are all included. A percentile says where a value sits among Americans of that sex and age, not whether it is normal.
Use the left and right arrow keys to read each age. Shift moves five years.
Reference data derived from CDC/NCHS National Health and Nutrition Examination Survey (NHANES), cycles 2015-2016, 2017-March 2020 (pre-pandemic), August 2021-August 2023. Analysis by bloodtesttracker.com; not endorsed by CDC, NCHS or HHS.
Explore LDH by age and sex: every percentile as a table, with a download.
What can affect your result
- Age: children have higher levels than adults
- Sex: adult limits are very close for men and women
- Hemolysis of the blood sample, or red cells left in contact with the serum for too long
- Recent intense exercise
- Medicines such as aspirin; vitamin C and E supplements
- Assay method: labs measure the reaction in different directions, so reference ranges differ between labs
- Which tube was used: EDTA, oxalate and fluoride tubes are not accepted by ARUP
- A blood sample in which red blood cells have broken open (hemolysis) reads falsely high, and ARUP rejects hemolyzed specimens.
- ARUP asks for serum or plasma to be separated from the cells within 2 hours, and does not accept EDTA, oxalate or fluoride tubes.
- Intense exercise and some medicines, including aspirin, can raise LDH (MedlinePlus).
- Large amounts of vitamin C or vitamin E may lower it (MedlinePlus).
Varies with the cause. After a one-off event such as hard exercise, a repeat after rest usually shows whether the rise was temporary.
When to talk to a clinician
No urgent LDH value has been published by the large reference labs that were checked. The result matters most together with how you feel. See a clinician soon if a high result comes with unexplained weight loss, drenching night sweats, fevers, yellow skin or eyes, dark urine, unusual tiredness, severe muscle pain or weakness. If you have chest pain, trouble breathing, confusion or fainting, call 911 or your local emergency number.
Questions you could ask
- Why was LDH included in my tests, and what is it being compared with?
- How does my LDH fit with my other results, such as my blood counts and liver tests?
- Could my sample have been hemolyzed, or could exercise or a medicine explain this result?
- Should we repeat the test, and which other tests would help put it in context?
- Would an isoenzyme test or other follow-up help find where the LDH is coming from?
- Does a low LDH need any follow-up in my case?
Questions people ask
Does a high LDH mean I have cancer?
Not by itself. LDH is a general marker of tissue damage, and the most common reasons for a higher result are things like a hemolyzed blood sample, hard exercise, muscle injury, liver or red blood cell conditions and some medicines. Doctors also use LDH when they follow certain cancers, but a high result alone does not point to one. Your clinician can put it in context.
Why does my lab's range look different from the ranges I see online?
Labs measure LDH with different methods, and the reference range depends on the method. Reported adult ranges include about 121 to 224 U/L at Labcorp, 125 to 220 IU/L on MedlinePlus and 80 to 225 U/L from ABIM. Use the range printed on your own report.
Can exercise or a hard blood draw change my LDH?
Yes. Intense exercise can raise LDH, and so can a blood draw that breaks open red blood cells in the tube. If your result is only a little high and you were active before the test, ask your clinician whether a repeat after rest makes sense.
Show the science and sources
Units
- 1 U/L = 1 U/L
- 1 U/L = 0.01667 µkat/L
- 1 U/L = 16.67 nkat/L
Is a change real?
LDH naturally varies about 5.2% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 15% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: The European Biological Variation Study (EuBIVAS): a summary report.
For clinicians and researchers
LDH is a tetrameric enzyme that interconverts lactate and pyruvate with NAD+/NADH. Five isoenzymes (LD1 to LD5), built from H and M subunits, are distributed differently across tissues: LD1 and LD2 predominate in heart and red cells, and LD4 and LD5 in liver and skeletal muscle. Total LDH is not organ-specific, and isoenzyme work-up is infrequent. Red cells hold far more LDH than serum, so in vitro hemolysis raises results and is the commonest pre-analytical error. Analytical direction matters: the lactate-to-pyruvate and pyruvate-to-lactate methods (LOINC 14804-9 and 14805-6) give different activities, so reference intervals vary by method and temperature. Intervals seen in the sources opened: Labcorp 121 to 224 U/L (men) and 119 to 226 U/L (women) over age 17, MedlinePlus 125 to 220 IU/L, ABIM 80 to 225 U/L. LDH is used as a prognostic factor in some cancers; for example, it is one of the serum tumor markers in the International Germ Cell Consensus Classification for metastatic germ cell tumors. No numeric critical limit for LDH appears on the Labcorp or ARUP critical-value lists.
LOINC 2532-0 (primary), 14804-9, 14805-6. Specimen: serum-or-plasma.
Sources
- LDH (test 001115) sample report, Labcorp
- Pediatric Testing Reference Ranges (LDH, test 001115, ages 0 to over 17), Labcorp
- Lactate Dehydrogenase, Serum or Plasma (test 0020006), ARUP Laboratories
- ABIM Laboratory Test Reference Ranges, January 2026, American Board of Internal Medicine (2026)
- Lactate dehydrogenase test, MedlinePlus (National Library of Medicine) (2026)
- Lactate Dehydrogenase (LDH) Test, MedlinePlus (National Library of Medicine)
- Critical (Panic) Values, Labcorp (2024)
- ARUP Critical Values, ARUP Laboratories
- International Germ Cell Consensus Classification: a prognostic factor-based staging system for metastatic germ cell cancers, Journal of Clinical Oncology (1997)
- LOINC 2532-0, 14804-9 and 14805-6 (NLM Clinical Tables), National Library of Medicine
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.