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Lactate Dehydrogenase (CSF)

Does this test have other names?

Lactic acid dehydrogenase (CSF), LDH CSF

What is this test?

This test measures the amount of the enzyme lactate dehydrogenase (LDH) in your cerebrospinal fluid (CSF).

CSF is the clear liquid that surrounds the brain and spinal cord. Enzymes are catalysts, or chemicals in your tissues and organs that cause the reactions necessary to provide energy to your cells.

This test can help diagnose diseases and conditions that affect your central nervous system, such as:

  • Jakob-Creutzfeldt disease, a rare, degenerative brain disorder that is fatal. Symptoms include impaired memory and judgment, impaired vision, muscle jerks, and personality changes. It primarily affects people in their 50s, 60s, and 70s.

  • Bacterial meningitis, an infection of the protective layers of tissue, or meninges, that surround the brain and spinal cord. Symptoms of bacterial meningitis include headache, fever, neck stiffness, nausea, vomiting, and confusion.

  • Neurosyphilis, an infection of the brain or spinal cord. Neurosyphilis is different from syphilis, a sexually transmitted disease, because it affects the nervous system. But people with untreated syphilis are susceptible to neurosyphilis. Neurosyphilis may have no symptoms, or it may cause headaches, memory loss, and visual problems.

  • Tumors of the central nervous system

Why do I need this test?

You may have this test if your doctor suspects that you have a disease or condition that affects your central nervous system.

You may also have this test to see if cancer has spread to your brain and spinal cord.

What other tests might I have along with this test?

Your doctor may also order a glucose test to measure the amount of sugar in your CSF.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Results are given in units per liter (units/L). Normal findings for lactate dehydrogenase in CSF are:

  • Less than or equal to 70 units/L for newborns

  • Less than or equal to 40 units/L for adults

If your LDH level is higher, it means you may have an infection or inflammation in your central nervous system.

Higher LDH levels may also mean you have a disease that affects your brain or spinal cord, such as bacterial meningitis, neurosyphilis, or tumors that have spread to the brain or spinal cord.

How is this test done?

This test requires obtaining a sample of your cerebrospinal fluid. Your doctor will take the sample through a lumbar puncture, or spinal tap, using a thin needle. The needle will be pushed into your lower back, and fluid will be removed.

Does this test pose any risks?

A lumbar puncture, or LP, carries these possible risks:

  • Headaches

  • Infection

  • Bleeding

  • Tumors

  • Numbness  

What might affect my test results?

Other factors aren't likely to affect your results.

How do I get ready for this test?

Empty your bladder and bowels before testing. In addition, be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.