Lactate Dehydrogenase
Also known as: LDH, LD
What Does Lactate Dehydrogenase Measure?
Lactate Dehydrogenase (LDH) is an enzyme found in nearly every cell of the body that plays a critical role in energy production. Specifically, it catalyzes the conversion of lactate to pyruvate (and vice versa) during the process of anaerobic respiration — the way cells generate energy when oxygen is limited. A blood test measures the total amount of LDH circulating in the bloodstream, which normally stays quite low since the enzyme is primarily contained within cells.
Why Does Lactate Dehydrogenase Matter?
When cells are damaged, stressed, or dying, they release LDH into the bloodstream, causing levels to rise. This makes LDH a sensitive but nonspecific marker of tissue damage — it signals that something is wrong somewhere in the body, but cannot pinpoint the exact location without additional tests. Clinically, LDH is used to monitor conditions like heart attack, liver disease, anemia, muscle injury, kidney disease, and cancer. It is especially valuable in oncology as a tumor marker for monitoring treatment response and disease progression in cancers such as lymphoma, leukemia, melanoma, and testicular cancer. Elevated LDH can also indicate poor prognosis in critically ill patients, including those with COVID-19 or sepsis.
Normal Ranges
Males
135–225 U/L (units per liter)
Females
135–214 U/L (units per liter)
Children
Varies by age; newborns 160–450 U/L, decreasing gradually to adult levels by late adolescence
Causes of High Levels
- Cancer and tumor activity (lymphoma, leukemia, melanoma, testicular cancer, and others)
- Heart attack (myocardial infarction) causing cardiac muscle cell death
- Liver disease or damage (hepatitis, cirrhosis, liver injury)
- Hemolytic anemia or other conditions causing red blood cell destruction
- Muscle damage from injury, intense exercise, rhabdomyolysis, or muscular dystrophy
- Kidney disease or infarction causing renal cell damage
- Pulmonary embolism or lung tissue damage
- Sepsis or severe systemic infections including COVID-19
Causes of Low Levels
- No established clinically significant causes of pathologically low LDH in most guidelines
How to Improve Your Lactate Dehydrogenase
Diet
- Reduce alcohol consumption, as alcohol is directly toxic to liver and muscle cells and raises LDH
- Follow an anti-inflammatory diet rich in fruits, vegetables, whole grains, and omega-3 fatty acids to reduce cellular stress
- Limit processed foods, refined sugars, and saturated fats that promote oxidative damage
- Ensure adequate hydration (8–10 cups of water daily) to support kidney function and cellular health
- Increase intake of antioxidant-rich foods such as berries, leafy greens, and nuts to protect cells from damage
Supplements
- Coenzyme Q10 (100–300 mg/day) may support cellular energy production and reduce oxidative stress causing cell damage
- N-Acetyl Cysteine (NAC, 600–1200 mg/day) can reduce oxidative stress and support liver detoxification
- Vitamin E (400 IU/day) as an antioxidant may help protect cell membranes from damage
- Magnesium (300–400 mg/day) supports muscle function and may reduce exercise-induced muscle cell damage
- Alpha-lipoic acid (300–600 mg/day) is a potent antioxidant that supports liver health and reduces cellular oxidative damage
Related Biomarkers
Frequently Asked Questions
What does it mean if my LDH is high?
An elevated LDH level means there is likely some degree of cell damage or tissue injury occurring in your body. However, LDH is nonspecific — it rises with damage to almost any tissue, including the heart, liver, muscles, kidneys, lungs, and blood cells. A high result by itself is not a diagnosis. Your doctor will typically order additional tests (such as liver enzymes, creatine kinase, or imaging) to identify the specific source of the elevation.
Can exercise cause high LDH levels?
Yes, intense or prolonged physical exercise can temporarily elevate LDH levels because vigorous muscle activity causes minor muscle cell breakdown, releasing LDH into the bloodstream. This is normal and typically resolves within 24–72 hours after rest. If you have a scheduled LDH test, it is advisable to avoid strenuous exercise for at least 24 hours beforehand to prevent a falsely elevated result.
Is LDH used as a cancer marker?
LDH is commonly used in oncology as a prognostic marker rather than a specific cancer diagnostic test. Elevated LDH is associated with more aggressive disease, higher tumor burden, and poorer outcomes in cancers such as lymphoma, leukemia, melanoma, and testicular cancer. Oncologists use serial LDH measurements to monitor treatment response — a falling LDH often indicates the treatment is working, while a rising level may signal disease progression.
What is the difference between total LDH and LDH isoenzymes?
Total LDH measures the overall amount of LDH in the blood from all sources. LDH isoenzymes (LDH-1 through LDH-5) are different forms of the enzyme found in higher concentrations in specific tissues. For example, LDH-1 and LDH-2 are predominantly found in the heart and red blood cells, while LDH-4 and LDH-5 are more specific to the liver and skeletal muscle. Testing isoenzymes used to be common to diagnose heart attacks, but has largely been replaced by more specific cardiac markers like troponin.