2. Body fluid analysis
• Cerebrospinal fluid analysis

3. • Introduction to Cerebrospinal fluid
• Routine laboratory assays
• Collection of sample
• Gross appearance
• Cell counts
• Chemical analysis
• Morphological Examination
• Microbiological Examination
• Serological Examination

4. CSF Formation and Physiology
First recognized by Cotugno in 1764, cerebrospinal fluid
(CSF) is a major fluid of the body.
CSF provides a physiologic system to supply nutrients
to the nervous tissue, remove metabolic wastes, and
produce a mechanical barrier to cushion the brain
and spinal cord against trauma.
CSF is produced in the choroid plexuses of the two
lumbar ventricles and the third and fourth venticles. In
adults, approximately 20 mL of fluid is produced every
hour.

5. Formation and Physiology
The fluid flows through the subarachnoid space
located between the arachnoid and pia mater.
To maintain a volume of 90 to 150 mL in adults
and 10 to 60 mL in neonates.
the circulating fluid is reabsorbed back into the
blood capillaries in the arachnoid
granulations/villae at a rate equal to its
production

6. Cerebrospinal fluid (CSF)
– Fluid in the space called sub-arachnoid space between the
arachnoid mater and pia mater
– Protects the underlying tissues of the central nervous
system (CNS)
– Serve as mechanical buffer to
• prevent trauma,
• regulate the volume of intracranial pressure
• circulate nutrients
• remove metabolic waste products from the CNS
• Act as lubricant
– Has composition similar to plasma except that it has less
protein, less glucose and more chloride ion

7. Cerebrospinal fluid analysis
– Collection of CSF sample
– Routine Laboratory assays of CSF
• Gross appearance
• RBC &WBC counts
• Morphological Examination
• Microbiological Examination
• Serological Examination

8. CSF Normal Adult Lab Ranges
• Normal CSF Levels:
Protein (10 - 45 mg/dL)
Glucose (40 - 70 mg/dL)
• Physical Appearance
Clear/colorless
RBC <5/mL
WBC <5/mL

9. Cont..
• Maximum volume of CSF
– Adults 150 mL
– Neonates 60 mL
• Rate of formation in adult is 450-750 mL per day or 20 ml per hour
– reabsorbed at the same rate to maintain constant volume
• Collection by lumbar puncture done by experienced medical
personnel
• About 1-2ml of CSF is collected for examination
– lumbar puncture is made from the space between the
4th and 5th lumbar vertebrae under sterile conditions

10. Collecting CSF specimen
 Collected in three sequentially labeled tubes
 Tube 1 Chemical and immunologic tests
 Tube 2 Microbiology
 Tube 3 Hematology (gross examination, total WBC & Diff)
 This is the list likely to contain cells introduced by the
puncture procedure

11. Report the appearance of the c.s.f.
• As soon as the c.s.f. reaches the laboratory,
note its appearance.
Report whether the fluid:
• – is clear, slightly turbid, cloudy or definitely
purulent (looking like pus),
• – contains blood,
• – contains clots.
Normal c.s.f. Appears clear and colourless.

12. Report the appearance of the c.s.f…
• Purulent or cloudy c.s.f.
Indicates presence of pus cells, suggestive of acute
pyogenic bacterial meningitis.
• Blood in c.s.f.
This may be due to a traumatic (bloody) lumbar
puncture or less commonly to haemorrhage in the
central nervous system. When due to a traumatic
lumbar puncture, sample No. 1 will usually
contain more blood than sample No. 2.

13. Report the appearance of the c.s.f…
• Following a subarachnoid haemorrhage, the
fluid may appear xanthrochromic, i.e. yellow-
red (seen after centrifuging).
• Clots in c.s.f. Indicates a high protein
concentration
• with increased fibrinogen, as can occur with
• pyogenic meningitis or when there is spinal
constriction.

14. Clinical Significance
Diagnosis of meningitis of bacterial, fungal,
mycobacterial and amoebic origin or
differential diagnosis of other infectious
diseases
subarachnoid hemorrhage or intracerebral
hemorrhage

15. Principle of the test
• CSF specimen examined visually and microscopically and
total number of cells can be counted and identified
Specimen:
• the third tube in the sequentially collected tubes
• must be counted within 1 hour of collection (cells
disintegrate rapidly). If delay is unavoidable store 2-8oC.
• All specimens should be handled as biologically
hazardous

16. Microscopic Observations of Cerebral
Spinal Fluid
Physical Examination
• Color – Xanthochromia
– Hyperbilirubinemia
– Increased Protein
• Turbidity
– Increased White Blood Cells (Pleocytosis)

17. CSF Supernatant
• A traumatic tap shows progressively decreasing
RBC in serial samples
• Generally, in subarachnoid hemorrhage, the RBC
would be consistent from one tube to the next
• After the CSF is centrifuged, the supernatant fluid
is clear in a traumatic tap, but it is xanthochromic
in a subarachnoid hemorrhage
• Xanthochromia of the CSF refers to a pink,
orange, or yellow color of the supernatant after
the CSF has been centrifuged

18. Cell Count
• The white cell count is increased when there is
inflammation of the central nervous system,
particularly the meninges
• Bacterial infections are usually associated with
the presence of neutrophils in the CSF

19. Cell Count…
• Viral infections are associated with an increase in
mononuclear cells
• An increase in mononuclear cells may also be seen
with:
– cerebral abscess
– acute leukemia
– Lymphoma
– intracranial vein thrombosis
– cerebral tumor
– multiple sclerosis

20. Cell Count…
• A white cell count with an indication whether
the cells are pus cells or lymphocytes, is
required when the c.s.f. appears slightly
cloudy or clear or when the
• Gram smear does not indicate pyogenic
bacterial meningitis

21. Chemistry Tests
• Because CSF is formed by filtration of the plasma,
chemicals in the CSF are that are found in the
plasma.
• chemical composition is controlled by the blood-
brain barrier,
• normal values for CSF chemicals are not the same
as the plasma values.
• Abnormal values result from alterations in the
permeability of the blood-brain barrier or increased
production or metabolism by the neural cells in
response to a pathologic condition.
.

22. Measurement of c.s.f total protein
• Use the supernatant fluid from centrifuged
c.s.f. or uncentrifuged c.s.f. when the sample
appears clear.
• Total protein can be measured in c.s.f. using a
colorimetric technique or a visual comparative
technique,
• Normal Total c.s.f. protein is normally 0.15–
0.40 g/l (15–40 mg%).

23. Measurement of c.s.f total protein ….
• When the total protein exceeds 2.0 g/l (200
mg%), the fibrinogen level is usually increased
sufficiently to cause the c.s.f. to clot. This may
occur in severe pyogenic meningitis, spinal
block, or following haemorrhage.

24. Clinical Significance of Elevated Protein
Values
• The causes of elevated CSF protein include
damage to the blood-brain barrier, production of
immunoglobulins within the CNS, decreased
clearance of normal protein from the fluid, and
degeneration of neural tissue.
• Meningitis and hemorrhage conditions that
damage the blood-brain barrier are the most
common causes of elevated CSF protein.
• Many other neurologic disorders can elevate the
CSF protein, and finding an abnormal result on
clear fluid with a low cell count is not unusual

25. Increased CSF Protein >80mg/dL
• Diabetes Mellitus
• Brain tumor
• Meningioma
• Acoustic neuroma
• Ependymoma
• Encapsulated brain abscess
• Spinal cord tumor
• Multiple Sclerosis
• Acute purulent Meningitis

26. Increased CSF Protein >80mg/dL…
Granulomatous Meningitis
Carcinomatous Meningitis
Syphilis (protein may be normal if longstanding)
Guillain-Barre Syndrome (Infectious polyneuritis)
Cushing's Disease
Connective tissue disease
Uremia
Myxedema
Cerebral hemorrhage

27. Cerebrospinal Fluid Glucose
• Glucose enters the CSF by selective transport
across the bloodbrain
• barrier, a normal value 60% to 70% that of the
plasma glucose.
• If the plasma glucose is 100 mg/dL, then a normal
CSF glucose would be approximately 65 mg/dL.
For an accurate evaluation of CSF glucose, a
blood glucose test must be run for
comparisonCSF glucose is analyzed using the
same procedures employed for blood glucose.
• Specimens should be tested immediately because
glycolysis occurs rapidly in the CSF.

28. Clinical Significance of Elevated
glucose Values
The diagnostic significance of CSF glucose is confined
to the finding of values that are decreased in relation to
plasma values.
Elevated CSF glucose values are always a result of
plasma elevations.
Low CSF glucose values can be of considerable
diagnostic value in determining the causative agents
in meningitis.
The finding of a markedly decreased CSF glucose
accompanied by an increased WBC count and a large
percentage of neutrophils is indicative of bacterial
meningitis.