Lactate Dehydrogenase (LDH) Activity in Serum/Plasma
This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in converting lactate to pyruvate during energy production in cells. It is often checked to assess cell damage or metabolic function.
["LDH helps identify conditions affecting cell health or energy metabolism."]
Key facts at a glance
- LOINC
- 51509-8
- Short code
- LDH1 CFr Prt Elph
- Synonyms
- LDH1 CFr Prt Elph
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 140
- Ref high
- 280
- Critical range
- 7.2 N/A – 7.6 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- electrophoresis
- CPT
- 83615
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Doctors may order LDH testing to evaluate symptoms like muscle weakness, fatigue, or organ dysfunction. It can also help diagnose conditions such as heart attacks, liver disease, red blood cell disorders, or certain cancers. LDH levels may rise when tissues are damaged, indicating inflammation or injury.
What Does a High or Low LDH Level Mean?
Elevated LDH levels may suggest damage to organs (like the heart, liver, or kidneys), certain cancers, or blood disorders. Lower levels might be seen in rare cases of genetic enzyme deficiencies or specific metabolic conditions, but this is less common. Your doctor will interpret results in relation to your symptoms and overall health.
Common Conditions Monitored with LDH
LDH is frequently monitored in patients with suspected heart attacks (myocardial infarction), liver disease, anemia, or blood cancers like leukemia. It can also be part of routine follow-up for chronic conditions like heart or kidney disease.
Sample Collection and Preparation
A blood sample is typically drawn from a vein in your arm. The sample is collected in a tube that separates serum or plasma from blood cells. This liquid portion is then sent to a lab for testing. You may be asked to fast before the test, but this depends on your doctor’s instructions.
Reference range
Adult: 140-280 U/LN/A
No special preparation required. Inform provider of any chest pain or symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
LDH is a useful biomarker because it is widely distributed in tissues and can rise in response to cellular injury. Elevated LDH levels often correlate with tissue damage, but they can also be influenced by factors like age, sex, or certain medications. Doctors use LDH alongside other tests to narrow down potential causes of symptoms.
Short name
LDH Activity
Frequently asked questions
How long does it take to get LDH test results?
Can lifestyle changes affect LDH levels?
What if my LDH level is outside the normal range?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy