Cerebrospinal fluid (CSF) is a transcellular fluid produced mainly in the choroid plexuses of the brain, with a daily production of 500-600ml but an active volume of 120-150ml at any time. CSF serves essential functions such as acting as a shock absorber, regulating intracranial pressure, and transporting nutrients and waste. Lumbar punctures are indicated for conditions like meningitis, subarachnoid hemorrhage, and other CNS diseases.

1. RITESH SRIVASTAVA
DEPARTMENT OF BIOCHEMISTRY
SHRIDEV SUMAN SUBHARTI MEDICAL
COLLEGE DEHRADUN

2. Cerebrospinal fluid (CSF) is a biologic
transcellular fluid, formed mainly in the
ventricular plexus, distributed within the
ventricular system, basal cisterns, and
subarachnoid space.

3.  CSF is formed in the cluster of capillaries in the walls
of the ventricles, called the choroid plexuses, filter
blood to continuously form about 500-600ml of CSF
everyday.
 However, at any given time, there is about 120-150ml
CSF in the system. Further , CSF is completely
replaced about three times a day.
 This CSF then flows in the two lateral ventricles and
then passes through the paired interventricular foramina
of monro into the third ventricle.

4.  CSF then flows caudally through the aquaduct
of Sylvius and fourth ventricle and into the
subarachnoid space.

6. PARAMETER CONCENTRATION
Volume 90-150ml
Appearance Clear and colourless
Specific Gravity 1.006-1.008
Osmolality 280-290 mOsm/kg
Total cell count 0-5 cumm
pH 7.3-7.4
Protein 15-45 mg/dl
A/G Ratio 8:1
Glucose 45-85 mg/dl
Sodium 145-155mEq/l
Potassium 2.0-3.5mEq/l
Chloride 118-130mEq/l

7. As the brain has no lymphatic system, CSF drains into
the ventricular system and moves into spaces
surrounding the brain and spinal cord.
The major functions of CSF are:-
 CSF serves as a hydraulic shock absorber.it can diffuse
the force from a hard blow to the skull that might
otherwise cause severe injury.

8.  It helps in the regulation of intracranial
pressure.
 It is believed that CSF influences the hunger
sensation and eating behaviors.
 Transports nutrient, chemical messengers , and
waste products.

9. Lumber puncture should be performed for the following
indication:-
 Suspicion of meningitis
 Suspicion of subarachnoid hemorrhage
 Suspicion of CNS diseases such as Guillain-Barre
syndrome and carcinomatous meningitis
 Therapeutic relief of pseudo tumor cerebri.

12. COLOUR:-
Normal CSF is crystal clear
Yellow / Xanthochromic:- Hyperbilirubinemia- Due to
presence of bilirubin originating from catabolism of
hemoglobin.
RED:- Traumatic tap.
subarachnoid hemorrhage, Intracranial bleed.

13. APPEARANCE:-
Normally CSF is clear
 Turbid:- when cells are >500/μl purulent
neuroinfections , Presence of erythrocytes.
 Cloudy:- Due to presence of leukocytes
 Coagulum:- When protein content is increased.

15. GLUCOSE:-
A true normal range cannot be given for CSF glucose.
2/3 of serum glucose
 Lower values of glucose in CSF- Bacterial CNS
infection
 Elevated CSF glucose level- Elevated levels of glucose
in blood is the only cause of having an elevated CSF
glucose level. There is no pathological causes CSF
glucose levels to be elevated.

16. PROTEIN:-
The CSF contain about 200 fold less protein than that of
blood plasma.
About 80% of the CSF protein come from plasma.
Protein is falsely elevated by the presence of RBCs in a
traumatic tap.
CSF protein is increase in:-
Bacterial meningitis, brain tumor , Brain abscess. etc

17. Colour…………………..
Appearance……………
Coagulum……………..
Glucose………………..
Protein…………………
Chloride……………….