BIOCHEMISTRY PRACTICALBy: Dr. Beenish Zaki

CSF ANALYSIS

CEREBROSPINAL FLUID

The surface of the central nervous system is covered by the meninges: Duramater Arachnoid Piamater.

The space between arachnoid and piamater is called sub-arachnoid space.

CSF is secreted by the choroid plexuses. In normal healthy adults rate of CSF formation is

100-250ml/24hrs.

CSF FORMATION AND CIRCULATION

SITE OF WITHDRAWL

•CSF is withdrawn by a procedure called lumbar puncture.•Spinal cord ends near the first lumbar vertebra.•CSF is obtained by passing Lumbar Puncture (L.P) needle between L4-L5.•Second preferred site is L3-L4 into the sub-arachnoid space.

SITE OF LUMBAR PUNCTURE

NORMAL COMPOSITION:

Colour : Clear colorless; no coagulum or deposit

PH : 7.3

Pressure:60-150 mm of Hg

Specific gravity: 1.006-1.002

Cells : 0-4 mononuclear cells/mm3

Protein content: 10-45mg/dl

Globulins: absent

Glucose: 45-100mg/dl

Chlorides: 120-130meq/l

MEASURING OPENING PRESSURE

ABNORMALITIES

In appearance

Blood stained  a)Due to traumatic tap RBC under microscope

have normal shape   b) In pathological conditions like sub-arachnoid

haemorrhage in this blood is homogeneously mixed with CSF under microscope RBC have a crenated appearence.

ABNORMALITIES CONT’

In appearance Xanthochromia:-Yellow colorization of CSF

due to either: bilirubin Carotenoids

Turbidity :- is due to presence polymorphs/mm3

Coagulum:- In tuberculosis meningitis cob-web like coagulum is seen if the fluid is allowed to stand overnight from the web tubercle bacilli can be examined easily under microscope.

ABNORMALITIES CONT’

In Glucose  CSF glucose is increased in :- Diabetes  Encephalitis Cerebral abscess CSF glucose is decreased in :- Meningitis due to  bacteria. The glucose reduces from the fluid because

the organisms are glycolytic and thus use up the glucose.

A CASE

A 19 year old student presents with fever, headache, nausea, vomiting. On

examination there is neck stiffness.

INDICATION FOR CSF COLLECTION

CSF infection

Hemorrhage

Malignancy

Demyelinating Diseases

CSF PROTEINS ESTIMATION

METHOD AND PRINCIPLE

Method:Turbidity Method

Principle:Proteins are precipitated with Trichloro acetic acid which gives a turbidity.

PROCEDUREProcedure Blank(ml) Test(ml)

Sample - 1.00

ReagentTCA

4.00 3.00

Mix well and take reading immediately using green filter

OBSERVATION AND CALCULATION

O.D of Test= O.D of Standard=0.16 Concentration of sample =

O.D Test X concentration of standard (mg/dl)

O.D Standard

O.D Test x 100

  0.16

O.D-Optical Density

REFERENCE RANGE AND CLINICAL CONDITIONS

Adult: 10-45 mg/dl

CSF Protein Increased in: Meningitis Meningoma Acoustic Neuroma Multiple Sclerosis

CSF Protein Decreased in: Malnutrition

CSF CHLORIDE ESTIMATION

METHOD AND PRINCIPLE

Method: Titration Method

Principle:Chlorides present in CSF reacts with Silver nitrate to form silver chloride this reacts with the indicator to form a colored complex

PROCEDURE

Pipette 1ml of CSF and 2ml of distilled water into a conical flask.

Add 3 drops of potassium chromate as the indicator.

Titrate against silver nitrate in the burette to a faint brick red color which is the end point.

OBSERVATION AND CALCULATION

Initial Reading= Final Reading=

Concentration of sample:mEq. Chloride per liter of CSF= ml of silver nitrate solution required x 30

mEq/L= Milliequivalent/L

REFERENCE RANGE AND CLINICAL CONDITIONS

Adult: 90-120 mEq/L

CSF Chloride Increased in: Hypertension Renal disease

CSF Chloride Decreased in: Meningitis

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