CSF analysis

1. CSF Composition and
significance
Dr. Ashok Kumar .J.
International Medical School
Management and Science University
Malaysia

2. CSF Pressure
CSF pressure changes with
Posture
Blood pressure
Venous return
factors that increase cerebral blood
flow
• Normal opening pressure is 70 to 150
mm of water in left lateral decubitus
position
• Slightly higher in sitting up and varies
10 mm water with respiration
• In infants and young children the
normal range is 10 to 100 mm of
water
• Attain adult value by 6 to 8 years of
age
• Pressure may be as high as 250 mm
of water in obese individuals

3. Pressure above 250 mm of water are
diagnostic intracranial hypertension
1. Meningitis
2. Intracranial hemorrhage
3. Tumors
4. Thrombosis of venous sinuses
5. Cerebral edema
6. Conditions inhibiting absorption of CSF
7. Opening pressure elevated may be the
only abnormality in cryptococcal
meningitis
Decreased pressure
1. Spinal subarachnoid block
2. Dehydration
3. Circulatory collapse (shock)
4. CSF leakage
Significant drop in CSF pressure
after taking 1 to 2 ml of CSF
suggests herniation or spinal
block above the site of puncture

4. • CSF specimen should be sent to the lab immediately
• Delay might initiate cellular degradation (which begins within 1 hour
of collection)
Indication for CSF analysis
(Can be divided in to 4 categories)
1. Meningeal infection
2. Subarachnoid hemorrhage
3. Primary or metastatic malignancy
4. Demylinating disease
Identification of infectious meningitis especially bacterial is important
indication

5. CSF
• CSF collected into three sterile tubes for
1. Chemical and immunological studies
2. Microbiological examination
3. Cell count and differentiation
• An additional tube may be inserted for cytology if malignancy is
suspected
• Glass tubes should be avoided since cells adhere to glass affect the
cell count
• First tube should never be used for microbiological examination
( it may be contaminated with skin bacteria)

6. Gross examination
Normal CSF
• Crystal clear
• Has viscosity similar to water
Abnormal
• Cloudy
• Frankly purulent
• Pigmented or tinted
• Turbidity
• Coagulum
• Color
Turbidity or cloudiness begins to appear
with
• Leucocyte count over 200 cells /μL or
• Red cell count of 400 cell/ μL
• Grossly bloody CSF have RBC count
greater than 6000 / μL

7. Gross examination
Experienced observer may be
able to detect cell count less
than 50 cells / μL with unaided
eye by observing for Tyndll’s
effect
Turbidity or cloudiness
• Microorganisms bacteria, fungi,
amoeba
• Radiographic contrast material
• Aspirated epidural fat
• Protein level greater than 150 mgs/dl
• Turbidity
• Coagulum
• Color

8. Gross examination
Clot formation may be seen in traumatic tap
Not seen in subarachnoid hemorrhage
Fine surface pellicles may be seen after
refrigeration for 12 to 24 hours
Clot may interfere with cell count accuracy
by entrapping inflammatory cells
• Turbidity
• Coagulum
• Color

9. Gross examination
• Turbidity
• Coagulum
• Color
Viscous CSF may be encountered in
• Metastatic mucin producing adenocarcinoma
• Cryptococcal meningitis
Color : Pink red CSF - indicates presence of blood
May be derived from:
Subarachnoid hemorrhage
Intracerebral hemorrhage
cerebral infract
Traumatic tap

10. Xanthochromia
A pale pink to yellow color in the
supernatant of centrifuged CSF, although
other colors may be present
Pale pink to orange xanthochromia from
released oxyhemoglobin
usually detected 2–4 hours after the onset
of subarachnoid hemorrhage
(although it may take as long as 12 hours)
Peak intensity occurs in about 24-36
hours and then gradually disappears
over the next 4-8 days
Yellow xanthochromia is derived
from bilirubin
develops about 12 hours after a
subarachnoid bleed
peaks at 2-4 days, but may persist
for 2-4 weeks

11. To detect xanthochromia
The CSF should be centrifuged
and the supernatant fluid
compared with a tube of distilled
water
CSF supernatant color Associated diseases/disorders
Pink RBC lysis/hemoglobin breakdown products
Yellow Hyperbilirubinemia
CSF protein > 150 mg/dL (1.5 g/L)
Orange RBC lysis/hemoglobin breakdown products
Hypervitaminosis A (carotenoids)
Yellow-green Hyperbilirubinemia (biliverdin)
Brown Meningeal metastatic melanoma

12. CSF xanthochromia may also be due to the
following:
Oxyhemoglobin resulting from artifactual red cell
lysis caused by detergent contamination of the
needle or collecting tube
delay of more than 1 hour without refrigeration
before examination
Rifampin therapy (red-orange)
Bloody traumatic taps :
A traumatic tap occurs in about 20% of lumbar
punctures

13. Distinction of a traumatic puncture from pathologic hemorrhage is of vital
importance
Traumatic tap : Hemorrhagic fluid
usually clears between the first and
third collected tubes
Subarachnoid hemorrhage :
Remains relatively uniform
Traumatic tap : microscopic evidence
of erythrophagocytosis, or
hemosiderin-laden macrophages
indicate a subarachnoid bleed in the
absence of a prior traumatic tap
Hemosiderin-laden macrophages
(siderophages) from the CSF of a
patient with subarachnoid hemorrhage.
Hemosiderin crystals (golden-yellow)
are also present

14. Chemical Analysis
Analyte Conventional units
Protein 15–45 mg/dL
Pre-albumin 2–7%
Albumin 56–76%
Alpha-1-globulin 2–7%
Alpha-2-globulin 4–12%
Beta-globulin 8–18%
Gamma-globulin 3–12%

15. Total Protein.
Over 80% of the CSF protein content is derived from blood plasma, in
concentrations of less than 1% of the plasma level
Protein CSF (mg/L)
Prealbumin 17.3
Albumin 155.0
Transferrin 14.4
Ceruloplasmin 1.0
IgG 12.3
IgA 1.3
Alpha-2-microglobulin 2.0
Fibrinogen 0.6
IgM 0.6
Beta-lipoprotein 0.6

16. CSF protein levels of 15-45 mg/dl
accepted as the ‘normal’ reference
range
infants have significantly higher CSF
protein levels than older children
and adults
• CSF protein concentration fall rapidly
from birth to 6 months of age
(40 mg/dL)
• Plateaued between 3 and 10 years
(32 mg/dL)
• Then rose slightly from 10-16 years
(41 mg/dL)
for term infants and for preterm
infants the upper levels were
150 mg/dl and 170 mg/dl

17. Increased CSF Total Protein
May be caused by
• Increased permeability of the blood–brain barrier
• Decreased resorption at the arachnoid villi
• Mechanical obstruction of CSF flow due to spinal block
above the puncture site
• An increase in intrathecal immunoglobulin synthesis

18. Conditions Associated
Traumatic spinal puncture
Increased blood–CSF permeability
• Arachnoiditis
(e.g., following methotrexate therap)
• Meningitis
(bacterial, viral, fungal, tuberculous)
• Hemorrhage
(subarachnoid, intracerebral)
Drug toxicity
Ethanol, phenothiazines, phenytoin
CSF circulation defects
• Mechanical obstruction
(tumor, abscess, herniated disk)
• Loculated CSF effusion
Increased IgG synthesis
Neurosyphilis
Multiple sclerosis
Subacute sclerosing panencephalitis
Increased IgG synthesis and
blood–CSF permeability
• Guillain–Barré syndrome
• Collagen vascular diseases (e.g.,
lupus, periarteritis)

19. Qualitative tests for globulins
Pandy’s test :
• One drop of CSF is added to one ml of Pandy’s reagent (clear 7%
solution of phenol in water)
• A turbidity indicates increased globulin in CSF
Nonne-Apelt test :
• One ml of CSF is slowly layered over one ml of ammonium sulphate
solution
• A white ring at the junction of the two liquids indicates the
increased globulins

20. Quantitative test
Turbidimetric methods
Based on trichloroacetic acid (TCA) or sulfosalicylic acid (SSA)
and sodium sulfate for protein precipitation
Simple, rapid, and require no special instrumentation

21. Albumin and IgGMeasurements
Permeability of the blood–brain barrier may be assessed by
immunochemical quantification of the CSF albumin-to-serum
albumin ratio in grams per deciliter (g/dL)
The normal ratio of 1:230 ( 0.004)
- CSF/serum albumin index
- Arbitrarily calculated as follows
CSF/ Serum albumin index =
CSF albumin (mg/dl)
Serum albumin (g/dl)

22. An index value less than 9 is
consistent with an intact barrier
Slight impairment is considered with
index values of 9-14
Moderate impairment with values of
14-30
Severe impairment at values greater
than 30
Traumatic tap invalidates the index
calculation

23. CSF IgG index
Elevated “IgG index” indicates increased production of IgG within the
CNS : e.g Multiple sclerosis
CSF IgG index =
Serum albumin g/ dl
CSF IgG mg/ dl X
Serum IgG g/ dl X CSF albumin mg/ dl
Normal upper limit is 0.8

24. Approximately 300 different proteins have been identified in CSF
Protein Major diseases/disorders
• Alpha-2-macroglobulin Subdural hemorrhage, bacterial meningitis
• Beta-amyloid and tau proteins Alzheimer's disease
• Beta-2-microglobulin Leukemia/lymphoma
• C-reactive protein Bacterial and viral meningitis
• Fibronectin Lymphoblastic leukemia, AIDS, meningitis
• Methemoglobin Mild subarachnoid/subdural hemorrhage
• Myelin basic protein Multiple sclerosis, tumors, others
• Protein 14-3-3 Creutzfeldt–Jakob disease
• Transferrin CSF leakage (otorrhea, rhinorrhea)

25. Cerebrospinal fluid leakage
otorrhea
rhinorrhea
usually presents as otorrhea or
rhinorrhea following head trauma, in
some cases beginning months to
years after the injury
Recurrent meningitis is a serious
complication making accurate
identification of the leaking fluid very
important
Transferrin-
• an iron-binding glycoprotein
• synthesized primarily in the liver
• Two transferrin isoforms are present
in the CSF
• Major isoform (beta-1-transferrin) is
present in all body fluids
• The second isoform (beta-2-
transferrin), present only in the
central nervous system - is produced
in the central nervous system by the
catalytic conversion of beta-1-
transferrin by neuraminidase

26. Methemoglobin and Bilirubin
Subarachnoid and intracerebral hemorrhage are readily identified by
computed tomography (CT)
 Mild subarachnoid hemorrhage
 Small subdural or cerebral
hematomas
 Blood seepage from
• aneurysm or neoplasm
• from small cerebral infarcts are
often not identified by this
technique
CSF spectrophotometric analysis has
been shown to detect methemoglobin
in colorless CSF (< 0.3 μmol/L)
Increase in CSF bilirubin is now
recognized as the key finding
supporting the diagnosis of
subarachnoid hemorrhage

27. Glucose
• Derived from blood glucose
• fasting CSF glucose levels are normally 50-80 mg/dL
(about 60% of plasma values)
• Results should be compared with plasma levels, ideally following a
4-hour fast, for adequate clinical interpretation
• The normal CSF/plasma glucose ratio varies from 0.3 - 0.9
• CSF values below 40 mg/dL are considered to be abnormal
• Hypoglycorrhachia is a characteristic finding of bacterial, tuberculous,
and fungal meningitis

28. Decreased CSF glucose results from
• Increased anaerobic glycolysis in brain tissue and leukocytes
• Impaired transport into the CSF
• CSF glucose levels normalize before protein levels and cell counts
during recovery from meningitis, making it a useful parameter in
assessing response to treatment.

29. Lactate
• CSF and blood lactate levels are largely independent of each other
• Reference interval for older children and adults is 9.0-26 mg/dL
• Newborns have higher levels, ranging from about 10-60 mg/dL for the
first 2 days, and 10-40 mg/dL for days 3 to 10
• Elevated CSF lactate levels reflect CNS anaerobic metabolism due to
tissue hypoxia.

30. • Lactate measurement has been used as an adjunctive test in
differentiating viral meningitis from bacterial, mycoplasma, fungal,
and tuberculous meningitis in which routine parameters yield
equivocal results.
• Viral meningitis, lactate levels are usually below 25 mg/dL (almost
always less than 35 mg/dL)
• Bacterial meningitis typically has levels >35 mg/dL
• Persistently elevated ventricular CSF lactate levels are associated with
a poor prognosis in patients with severe head injury

31. F2-isoprostanes
• F2-isoprostanes are increased in diseased regions of the brain in
patients with Alzheimer's disease (AD)
• CSF F2-isoprostanes are also elevated in patients with probable AD
• In conjunction with CSF tau and beta-amyloid protein, the
measurement of CSF F2-isoprostanes appear to enhance the accuracy
of the laboratory diagnosis of AD

32. Enzymes
• A wide variety of enzymes derived from brain tissue, blood, or cellular
elements have been described in the CSF.
• Although CSF enzyme assays are not commonly used in the diagnosis
of CNS diseases, there are diseases/disorders whereby they may
prove useful.

33. Adenosine deaminase (ADA).
• ADA catalyzes the irreversible hydrolytic deamination of adenosine to
produce inosine.
• ADA is particularly abundant in T lymphocytes
• Which are increased in tuberculosis
• Higher ADA levels are present in tuberculous infections than in viral,
bacterial, and malignant diseases
• ADA levels greater than 15 U/L were found to be a strong indication of
tuberculous meningitis
• Non-tuberculous meningitis consistently had levels less than 15 U/L

34. Creatine kinase (CK).
• Brain tissue is rich in CK
• Increased CSF CK activity has been reported in disorders
• Hydrocephalus
• Cerebral infarction
• Primary brain tumors
• Subarachnoid hemorrhage
• Head trauma, CSF CK levels correlate directly with the severity of the
concussion
• CK-BB isoenzyme comprises about 90% of brain CK activity
and mitochondrial CK (CKmt) the other 10%, CK isoenzyme
measurements are more specific for CNS disorders

35. • CSF CK-BB is increased about 6 hours following an ischemic or anoxic insult
• Global brain ischemia following respiratory or cardiac arrest results in
diffuse cerebral injury with peak CK-BB levels in about 48 hours
• CSF CK-BB activity less than 5 U/L (upper normal level) indicates minimal
neurologic damage
• 5-20 U/L indicates mild to moderate CNS injury
• Levels between 21-50 U/L are commonly correlated with death.
• Death occurs in essentially all patients with levels above 50 U/L.

36. Lactate dehydrogenase (LD).
• LD activity is high in brain tissue
• A total LD activity of 40 U/L is a reasonable upper limit of normal for
adults and 70 U/L for neonates
• LD levels are also increased in patients with CNS leukemia,
lymphoma, metastatic carcinoma, bacterial meningitis, and
subarachnoid hemorrhage

37. Lysozyme.
• Normal CSF activity is very low
• Lysozyme (muramidase) catalyzes the depolymerization of
mucopolysaccharides.
• Since the enzyme is particularly rich in neutrophil and macrophage
lysosomes, its activity is very low in normal CSF
• CSF lysozyme activity is significantly increased in patients with both
bacterial and tuberculous meningitis

38. Ammonia, Amines, and Amino Acids.
• CSF ammonia levels vary from 30-50% of the blood values
• Measurement of CSF ammonia has little, if any, clinical value
• Cerebral glutamine, synthesized from ammonia and glutamic acid,
• Serves as the means for CNS ammonia removal
• CSF glutamine levels reflect the concentration of brain ammonia
• Values over 35 mg/dL are usually associated with hepatic encephalopathy
• Elevated CSF glutamine levels have also been reported in patients with
encephalopathy secondary to hypercapnia and sepsis

39. Osmolality 280–300 mOsm/L
Sodium 135–150 mEq/L
Potassium 2.0–3.5 mEq/L
Chloride 120–130 mEq/L
Carbon dioxide 20–25 mEq/L
Calcium 2.0–2.8 mEq/L
Magnesium 2.4–3.0 mEq/L
Lactate
10–22 mg/dL
Glutamine
6 – 11 mg/ dL
Iron
1 – 2 mg/dL
Cholesterol
0.2 – 0.6 mg/dL
Creatinine
0.5 – 1.2 mg/dL
Urea
6 – 16 mg/dL

40. pH
Lumbar fluid 7.28–7.32
Cisternal fluid
CSE bicarbonate
7.32–7.34
18 mmol/L
PCO2
Lumbar fluid 44–50 mmHg
Cisternal fluid 40–46 mmHg
PO2 40–44 mmHg

41. CSF chloride
• CSF chloride level is more compared to plasma chloride
• May be due to difference in the concentration of protein in plasma
and CSF
• CSF concentration of chloride decreases in meningitis – especially in
tubercular meningitis

42. Microscopic Examination
• Total Cell Count
• Cell counts are performed on undiluted CSF in a manual counting
chamber
• automated flow cytometry of CSF, using the UF-100 flow cytometer,
was found to yield rapid and reliable WBC and RBC counts

43. CSF Reference Values for Differential Cytocentrifuge Counts
Cell type Adults (%) Neonates (%)
Lymphocytes 62 ± 34 20 ± 18
Monocytes 36 ± 20 72 ± 22
Neutrophils 2 ± 5 3 ± 5
Histiocytes Rare 5 ± 4
Ependymal cells Rare Rare
Eosinophils Rare Rare
Correction when blood contaminated CSF
In the presence of a normal peripheral blood RBC count and serum
protein, these corrections amount to about 1 WBC for every 700 RBCs
and 8 mg/dL protein for every 10 000 RBC/μL

44. • Traumatic puncture may result in the presence of bone marrow
cells, cartilage cells, squamous cells, ganglion cells, and soft tissue
elements
• In addition, ependymal and choroid plexus cells may rarely be seen
Cluster of blast-like cells in CSF
from premature newborn

45. Increased CSF neutrophils occur in numerous
conditions
• Early bacterial meningitis - the proportion of PMNs usually exceeds
60%
• About one-quarter of cases of early viral meningitis the proportion of
PMNs also increases

46. Causes of Increased CSF Neutrophils
• Meningitis
Bacterial meningitis
Early viral meningoencephalitis
Early tuberculous meningitis
Early mycotic meningitis
Amebic encephalomyelitis
• Other infections
Cerebral abscess
Subdural empyema
• Following CNS hemorrhage
Subarachnoid
Intracerebral

47. Lymphocytosis (> 50%) is not uncommon in early acute bacterial
meningitis
When the CSF leukocyte count is under 1000/μL Atypical reactive
lymphoplasmacytoid and immunoblastic variants may be present.
Blast-like lymphocytes may be seen admixed with small and large
lymphocytes in the CSF of neonates.

48. Causes of CSF Lymphocytosis
• Meningitis
Viral meningitis
Tuberculous meningitis
Fungal meningitis
Syphilitic meningoencephalitis
Leptospiral meningitis
Degenerative disorders
Multiple sclerosis
Guillain–Barré syndrome

49. • Plasma cells, not normally present in CSF, may appear in a variety of
inflammatory conditions along with large and small lymphocytes and in
association with malignant brain tumors
• Multiple myeloma may also rarely involve the meninges
Causes of CSF Plasmacytosis
• Acute viral infections
Guillain–Barré syndrome
Multiple sclerosis
Parasitic CNS infestations
Sarcoidosis
Subacute sclerosing panencephalitis
Syphilitic meningoencephalitis
Tuberculous meningitis

50. Typical Lumbar CSF Findings in Meningitis
Test Bacterial Viral Fungal Tuberculous
Opening pressure Elevated Usually normal Variable Variable
Leukocyte count ≥ 1000/μL < 100/μL Variable Variable
Cell differential Mainly neutrophils
Mainly
lymphocytes Mainly lymphocytes Mainly lymphocytes
Protein Mild–marked
increase
Normal–mild
increase
Increased Increased
Glucose Usually ≤ 40 mg/dL Normal Decreased Decreased: may be
< 45 mg/dL
CSF-to-serum
glucose ratio
Normal–marked
decrease
Usually normal Low Low
Lactic acid Mild–marked
increase
Normal–mild
increase
Mild–moderate
increase
Mild–moderate
increase

51. Thank you