lumbar puncture (also called a spinal tap) is a procedure to collect and look
at the fluid (cerebrospinal fluid, or CSF) surrounding the brain and
spinal cord. Many different tests can be done on the CSF. Some results will be
ready right away, some will take a few hours after the procedure, and others
will take several weeks.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
CSF is normally
clear and colorless.
Normal CSF pressure in the
lower back for an adult ranges from 90–180 millimeters (mm) water. For
children younger than 8 years old, the normal opening pressure range is 10–100 mm water.
The normal protein content of
CSF in an adult's lower back (lumbar) region is 15–45
milligrams per deciliter (mg/dL) or 150–450 milligrams per liter (mg/L). Older adults
and children may have higher values that are still in the
The normal range for glucose
content in the CSF is about 60% of the blood glucose level. The levels
may be slightly increased if the person has just eaten.
Normal CSF contains no
red blood cells (RBCs). The
white blood cell (WBC) count for adults is 0–5 WBCs
per cubic millimeter (mm3). Children may normally
have a higher WBC count. No
neutrophils are present.
No infectious organisms (such
as bacteria, fungi, or a virus) are found in the CSF sample. No tumor cells are
Blood in the CSF
can result from bleeding (hemorrhage) in or around the spinal cord or brain,
but it may also be caused by tiny blood vessel poked during the spinal tap. If
a brain hemorrhage has occurred, the color of the CSF may change from red to
yellow to brown over several days. Bleeding caused by the lumbar puncture
itself will show more red blood cells in the first sample collected than in
later samples. Cloudy CSF may mean an infection (such as
meningitis or a brain
abscess) is present.
High CSF pressure may occur as
a result of swelling (edema) or bleeding (hemorrhage) in the brain, infection
(such as meningitis),
stroke, or other circulatory problems. Below-normal
pressure may mean a blocked spinal canal.
A high level of protein may be
caused by bleeding in the CSF, a tumor or spread of a cancer from another area
of the body,
diabetes, infection, injury,
Guillain-Barré syndrome, severe
hypothyroidism, or other nerve diseases. An increase
antibodies (immunoglobulins) may be caused by
inflammation in people who have
immune system disorders, or other bacterial and viral
Low glucose levels in the CSF
are abnormal and may be caused by bacterial meningitis. Viral meningitis does
not often cause low glucose levels in the CSF. Brain hemorrhage may also cause
low glucose levels several days after bleeding begins. Higher-than-normal
glucose levels are often caused by diabetes.
Red blood cells (RBCs) in the
CSF can result from bleeding. High levels of white blood cells (WBCs) can indicate meningitis.
Tumor cells and abnormal levels of white blood cells can show cancer is present.
bacteria, or other organisms in the CSF means that an infection (such as
syphilis) or disease is present. Bacterial markers
antigens) that show up mean meningitis. Cultures or
stains of the CSF may also help show the cause of meningitis or
Your doctor may order other special tests on the CSF fluid
depending on your symptoms and past health.