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 health problems that affect your central nervous system, such as:

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

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

• Neurosyphilis. This is an infection of the brain or spinal cord. Neurosyphilis is different from syphilis, a sexually transmitted infection, because it affects the nervous system. But people with untreated syphilis are prone 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 need this test if your healthcare provider 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 healthcare provider may also order a glucose test to measure the amount of sugar in your CSF.

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

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

• Less than 70 units/L for newborns

• Less than 40 units/L for adults

If your LDH level is higher, it may mean you 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. These include bacterial meningitis, neurosyphilis, or tumors that have spread to the brain or spinal cord.

How is this test done?

This test is done by obtaining a sample of your CSF. Your healthcare provider will take the sample through a spinal tap (lumbar puncture), using a thin needle. The needle will be put into your lower back, and fluid will be removed.

Does this test pose any risks?

A lumbar puncture carries these possible risks:

• Headaches

• Infection

• Bleeding

• Tumors (years later)

• Back pain

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. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.