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Lactate Dehydrogenase (LDH) Activity in Serum

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

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in energy production in cells. It can help identify conditions affecting muscle, liver, heart, or red blood cells.

Quick summary

["LDH helps diagnose and monitor conditions linked to tissue damage or metabolic stress."]

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

Key facts at a glance

LOINC
17041-5
Short code
LDH Ur Ql
Synonyms
LDH Ur Ql
Category
chemistry
Sample
urine
Container
Sterile urine container
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
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is LDH Used For?

LDH is often checked when doctors suspect damage to organs like the heart, liver, or kidneys, or when red blood cells are broken down (hemolysis). It may also be used in cancer screening or monitoring certain blood disorders.

Why Might You Need This Test?

Your doctor may order LDH if you have symptoms like chest pain, unexplained fatigue, jaundice (yellow skin), or signs of infection. It’s sometimes included in broader tests for conditions like heart attacks, liver disease, or anemia.

How Is the Test Done?

A blood sample is drawn from a vein in your arm. The sample is sent to a lab where LDH activity is measured using an automated test method. Results are typically available within 24–48 hours.

What Do Results Mean?

Elevated LDH levels may indicate tissue damage or disease, but interpretation depends on your overall health and other test results. Your doctor will discuss findings with you.

Reference range

Adult: 140-280 U/LN/A

Specimen: urine

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

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Serum

Frequently asked questions

Can LDH levels change with diet or exercise?
Dietary changes or intense exercise can temporarily affect LDH levels, but these are usually minor compared to conditions causing significant elevation. Your doctor will consider lifestyle factors when reviewing results.
Is LDH testing painful?
The blood draw itself may cause mild discomfort, but it’s generally quick and well-tolerated. Most people experience only minor bruising or soreness afterward.
How often is LDH retested?
Retesting depends on your condition. If LDH was elevated, your doctor may order follow-up tests to monitor changes over time, especially if you’re undergoing treatment for a suspected underlying issue.
  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