csf is the fluid which is present around the brain and spinal card as a shock absorber, provide nutrition and keep them wet. CSF analysis is an important tool in the diagnosis of many disease especially in meningitis and hemorrhages and for the diagnosis of many malignancy.
Muhammad Asif Zeb
CSF Lab Examination
Both the brain and spinal cord are covered by three
protective membranes referred to as the meninges.
The outermost layer is called the dura mater and is
composed of tough connective tissue.
The middle layer is the arachnoid named for it
spider web like appearance.
The delicate innermost layer which is in direct contact
with the brain and spinal cord is called the pia
mater. An inflammation of the meninges is referred
to as meningitis.
Between the arachnoid layer and the pia mater is a
space called the subarachnoid space.
It contains a clear, colorless fluid referred to as
Cerebrospinal Fluid (CSF).
CSF is produced in the ventricles of the brain by a
collection of rich vascular protrusions called the
Excess CSF is continuously reabsorbed by
arachnoid villi and returned to the venous system
thus maintaining a consistent amount of fluid
FUNCTIONS OF CSF
THE TWO CHIEF FUNCTIONS OF CSF (SPINAL)
1. To protect and cushion the brain and the spinal
cord against possible injury.
2. To deliver nutrients from the blood to the Central
Nervous System and removes
Thin, colourless, clear fluid
CSF is the 3rd
major fluid of the body
Adult volume 90-150 mL
Neonate volume 10-60 mL
0-5 WBC’s /mm3
(neonates 0-30/ mm3
(Lymphocytes & monocytes)
Occasional ependymal or choroid plexus cells
Chloride 113-130 mEq/L
Lumber puncture or collection
The procedure used to obtain
cerebrospinal fluid is referred to as
Lumbar Puncture or a Spinal Tap.
The purpose of CSF analysis is to diagnose
medical Disorders that affect the CNS.
Viral and Bacterial Infections.
Tumors of Nervous System.
Syphilis, a Sexually transmitted disease.
Bleeding around the brain and spinal cord.
Multiple sclerosis,a disease that affects the myelin
coating of the nerve fibers.
Guilain-Barre syndrome,an inflammation of the
Collection: 3-10 ml is collected
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Appearance of CSF
clear and colourless (normal);
bright red - This indicates the presence of blood.
The appearance of fresh blood in all three tubes
supports the diagnosis of a subarachnoid
xanthochromic (yellow) - jaundice
turbid - This indicates the presence of white cells
and is suggestive of a CNS infection.
Presence of clot
If present indicate high protein content
With patient traumatic tap
Complete spinal blockage
Clinical significance of Increase
Neutrophili leukocytosis =
Neisseria meningitis, Hemophilus influenza
and E. coli
T.b, Viral infection, fungus or with syphilis
Most patients with
fungal, tubercular and viral infection =
Plasma cell leukemia
Presence of tumor in brain.
Metastasis to CSF
Gram stain and culture
A Gram’s stain should be perform on all CSF
Cultures are also set up in order to retrieve and identify
organisms present in the CSF.
If the physician suspects a viral, mycobacterial, or rickettsia
it is important that special culture techniques be followed for
isolation of these organisms.
CSF PROTEIN DETERMINATION
CSF Glucose DETERMINATION
Normal CSF protein concentration is 15 - 45
mg/dl. It is derived from the plasma.
Increased levels are associated with:
- altered capillary permeability
- decreased absorption
- local biosynthesis of gamma globulin
Sulfosalicylic acid test
Take 3 ml of 3% sulfosalicylic acid in a
add 1 ml of supernatant clear CSF in it.
Cloudiness indicate the presence of
Principle (Biuret Method): Any
(proteins) containing three or more peptide
bonds reacts with alkaline copper tartrate
reagent to form a blue to purple coloured
The intensity of colour produced is proportional
to the number of peptide bonds reacting and,
therefore, to the amount of proteins.
To 2 ml CSF add 2 ml 10%trichloracetic acid, mix well and allow to
stand for 5 min.
Centrifuge at high speed and discard the supernatant.
Mark this tube containing precipitate as test.
Take another test tube and mark it blank.
To both tubes add 1 ml 15% NaOH. Shake the “test” tube to
dissolve them precipitate. Add 0.5 ml 5% Copper sulphate and 4 ml
Mix thoroughly and centrifuge at high speed.
Transfer the supernatant to corresponding clean tubes marked.
Read absorbance of the “test” against “blank” in a colorimeter at 550
CSF GLUCOSE DETERMINATION
• Normal CSF glucose is: 60 to 70 % of the patient's
serum glucose concentration.
It is generally decreased in bacterial meningitis, as well
as in meningitis associated with a fungus, tuberculosis
Decreased protein levels are less commonly
Common reasons are removal of large amounts of
CSF and leakage of CSF caused by trauma.
Glucose concentrations can be determined using the
same methodologies as used for blood.
The most common finding is a low glucose
concentration associated with most types of CNS
If patient is hyperglycemic, then the CSF glucose
concentrations will like wise be elevated and an
infection may be masked.
If the patient is hypoglycemic the physician may be
misled by a low CSF glucose.
Chemical analysis (Contd..)
Lactate determination is considered to be of
some use by physicians in differentiating
bacterial, tuberculous and fungal meningitis
from viral meningitis.
The lactate concentration in viral meningitis is
generally normal or low in comparison to that
in bacterial, tuberculous, or fungal meningitis.
Serologic examination of CSF is
typically involved with diagnosis of
A fluorescent treponemalantibody
absorption (FTA-ABS) test for CSF has
also been developed.
The VENERAL DISEASE RESEARCH
LAB. (VDRL) Test is also used.
TPHA test or TPPA test for syphlus
It is important to recognize other techniques that have
been used and may still be used for CSF.
Immunoelectrophorsis (CIE), latex agglutination tests
for bacterial antigens, enzyme linked immunosorbent
assay (ELISA) and limulus of gram-negative bacterial).
The nucleic acid probes using PCR are the newest of
the techniques being investigated for indentification of
specific infectious agents.