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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

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
14803-1
Short code
LDH Fld L to P-cCnc
Synonyms
LDH Fld L to P-cCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
100
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
reaction-lactate-to-pyruvate
CPT
83721
SNOMED
113079007
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?

Your doctor may order LDH testing to investigate symptoms such as muscle weakness, fatigue, chest pain, or unexplained bruising. It’s also used to evaluate liver function, detect heart damage, or check for conditions like anemia or certain cancers.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a few hours if the test is part of a liver function panel. Avoid strenuous exercise or consuming alcohol 24 hours before the test if instructed.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The blood sample is sent to a lab, where LDH activity is measured using an enzymatic method.

What Do the Results Mean?

Results are compared to a general reference range, but exact values can vary by lab. Elevated LDH levels may suggest tissue damage, while lower levels could indicate certain metabolic or genetic conditions.

Reference range

Optimal: <100 mg/dLN/A

Specimen: serum

Fasting for 12-14 hours preferred. Water is permitted. Avoid alcohol for 24 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Activity

Frequently asked questions

What causes elevated LDH levels?
Elevated LDH can result from damage to organs such as the heart, liver, or muscles, infections, blood disorders like anemia, or certain cancers. It may also appear in conditions like lupus or severe dehydration.
What causes low LDH levels?
Low LDH levels are less common and may occur in genetic disorders, certain medications, or in rare cases of metabolic disturbances. Your doctor will consider your overall health and other test results to interpret results accurately.
Can lifestyle changes affect LDH levels?
Yes, lifestyle factors like exercise, diet, and alcohol consumption may influence LDH levels. Avoiding excessive alcohol and engaging in regular, moderate exercise can sometimes help manage symptoms linked to elevated LDH.
  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