Skip to content

Lactate Dehydrogenase (LDH) Activity in Serum

Published: August 9, 2026Updated: August 17, 2026

This test measures the activity of an enzyme called lactate dehydrogenase (LDH) in your blood. LDH helps convert lactate to pyruvate and is found in many tissues, including the heart, liver, and muscles.

Quick summary

["LDH can help identify damage to cells in various organs."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
2527-0
Short code
LDH Amn-cCnc
Synonyms
LDH Amn-cCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Ref low
140
Ref high
280
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83615
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What Is LDH Used For?

LDH levels can help doctors diagnose and monitor conditions affecting different body systems. For example, high LDH may suggest damage to organs like the heart, liver, or muscles, or certain cancers. It’s also sometimes used to assess how well certain treatments are working.

Common Conditions Monitored

Elevated LDH is often checked alongside other tests when symptoms like fatigue, chest pain, or unexplained bruising appear. It may also be part of a broader evaluation for conditions like heart attacks, liver disease, or blood cancers.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where LDH activity is measured using an automated test that detects how quickly the enzyme converts a chemical substrate.

What Might Affect Results?

Factors like recent exercise, certain medications (e.g., some antibiotics or steroids), or underlying health conditions (like anemia or infections) can influence LDH levels. Always discuss your full medical history with your provider.

Reference range

Adult: 140-280 U/LN/A

Specimen: fluid

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

LDH Serum

Frequently asked questions

Why might my LDH level be checked?
Your doctor may order LDH testing if you have symptoms like muscle weakness, chest pain, or unexplained fatigue. It’s also used to monitor conditions like heart disease, liver problems, or blood disorders. LDH isn’t always definitive on its own but often helps guide further testing.
What do my LDH results mean?
Results are usually compared to a baseline or reference range for your age and health. Elevated LDH may signal cell damage, but it doesn’t always point to a specific cause. Your doctor will review the results with your full medical picture.
Can LDH levels change over time?
Yes, LDH levels can fluctuate depending on activity, illness, or treatment. If you have recurring tests, your doctor will track changes over time to assess trends, not just single results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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 17, 2026. · Read our editorial policy