Lactate Dehydrogenase (LDH) Activity, Cerebrospinal Fluid
This test measures the activity of lactate dehydrogenase in cerebrospinal fluid, the fluid surrounding the brain and spinal cord. It can help evaluate certain neurologic conditions when interpreted alongside symptoms, examination findings, and other laboratory tests.
["CSF LDH is an adjunctive test that may help assess central nervous system inflammation, infection, or tissue injury, but it cannot establish a diagnosis by itself."]
Key facts at a glance
- LOINC
- 2528-8
- Short code
- LDH CSF-cCnc
- Synonyms
- LDH CSF-cCnc
- Category
- chemistry
- Sample
- csf
- 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
- 1-2 mL
- Stability
- Immediate analysis required, Refrigerated: 1h
- Hemolysis max
- 200
- TAT
- 4–24 hours
- Order
- routine
What Is CSF LDH?
Cerebrospinal fluid is obtained through a lumbar puncture, commonly called a spinal tap. LDH is an enzyme found in many tissues, and its activity in CSF can reflect changes involving the brain, spinal cord, or their surrounding membranes.
Why Is the Test Performed?
A CSF LDH test may be ordered when symptoms suggest meningitis, encephalitis, or another central nervous system disorder. It may also be used as part of an evaluation of suspected brain or spinal cord inflammation.
What Do the Results Mean?
Higher LDH activity in CSF can occur with some infectious, inflammatory, or tissue-damaging conditions affecting the central nervous system. Results vary with the laboratory’s testing method and the clinical situation, so they should be interpreted using the laboratory’s reference information and the full clinical picture.
How Is the Test Different From Blood LDH?
CSF LDH measures enzyme activity in fluid surrounding the brain and spinal cord, whereas blood LDH measures enzyme activity in blood. The two results are not interchangeable, and blood contamination during the spinal tap can potentially affect the CSF result.
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.
◆Associated findings1
Short name
CSF LDH
Frequently asked questions
Does a high CSF LDH result diagnose meningitis?
Is a lumbar puncture painful or risky?
Yes. If blood enters the CSF sample during the procedure, it can increase the measured LDH activity. Laboratories may note visible blood contamination, and the result should be interpreted with that information and the other CSF findings.
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 17, 2026. · Read our editorial policy