Cerebrospinal Fluid Analysis:- Part 1 – Cerebrospinal Fluid (CSF) History and Normal Findings
Cerebrospinal Fluid Analysis (CSF)
History of the cerebrospinal fluid (CSF)
- Cotugno recognized it in 1794; CSF is the third major body fluid.
- CSF provides a physiologic system to supply nutrients to the nervous tissue.
- It removes metabolic wastes.
- It provides a cushion to the brain and spinal cord against trauma.
- The brain and spinal cord are lined by meninges, which consist of:
- The Dura mater is the outer layer.
- The Arachnoid mater is in between the outer and inner layers.
- The Pia mater is the inner layer.
- CSF flows through the arachnoidal space between the arachnoid and pia mater.
- 20 mL of CSF is produced every hour in the choroid plexus and reabsorbed by the arachnoid villi to maintain a total volume of 140 to 170 mL in adults and 10 to 60 mL in neonates.
Definition of the cerebrospinal fluid (CSF)
- It is a clear, colorless fluid similar to blood plasma and interstitial fluid.
- Approximately 600 mL of CSF is produced daily.
- Around 125 to 150 mL of CSF circulates in the ventricles and subarachnoid space.
- The choroid plexus in the lateral, third, and fourth ventricles produce a major portion of the CSF.
- CSF does not accumulate but is reabsorbed into venous circulation through arachnoid villi.
- The blood forms CSF, and after circulating throughout the CNS, it returns to the blood.
- CSF is secreted by the choroid plexus, around the cerebral vessels, and along the walls of the ventricles of the brain.
- It fills:
- Ventricle and cisternae.
- Bath the spinal cord.
- It is reabsorbed into the blood through the arachnoid villi.
- CSF turnover is rapid, exchanging about four times/day.
- >80% of the CSF protein contents originate from plasma by ultrafiltration and pinocytosis.
- The rest is from the intrathecal synthesis.
- As the CSF passes down the lumbar region of the spinal space, the protein concentration increases.
Functions of Cerebrospinal Fluid (CSF):
- The intracranial and the spinal cord float in the CSF and are protected from blows and jolts.
- The buoyant properties of the CSF prevent the brain from tugging on meninges, Nerve roots, and blood vessels.
- Its primary function is to protect the brain and spinal cord from injury.
- It transports the substances through the central nervous system.
- CSF is the ultrafiltrate of the plasma.
The appearance of CSF:
- Normal CSF Is clear and colorless.
- This clear CSF circulates in the subarachnoid space.
- No clot is seen.
The pressure of CSF:
- It is 70 to 180 mm H2O or 5 to 14 mm Hg (another reference = 100 to 200 mm H2O).
- This pressure is when the person is lying down and doubles up when the person sits up.
Total cell count in CSF:
- In adults, normal CSF contains 0 to 5 cells/cmm.
- These are mononuclear cells and lymphocytes.
- In newborns, the CSF cell count is 0 to 30/cmm, mostly neutrophils.
- Infants are 0 to 20 cells/cmm.
- No RBC is seen.
The glucose level of CSF:
- It is 45 to 80 mg /dL . The reference value is 45 mg/dL (2.5 mmol/L) or higher.
- In a normal person, it is rare to find glucose below 45 mg/dL.
- CSF glucose is 20 mg /dL lower than the blood glucose level.
- CSF glucose level is around 60% of the serum glucose level.
- In newborns, the CSF glucose level is 80% of the serum glucose level.
- The CSF glucose decrease is important to diagnose the various types of meningitis.
- Ventricular glucose is 5 to 10 mg higher than the lumbar CSF.
The protein level of CSF:
- Normal CSF protein is 15 to 45 mg/dL in lumbar CSF.
- It is 15 to 25 mg/dL in the cisternal fluid.
- It is 5 to 15 mg/dL in the ventricular fluid.
- In the newborn, the values are different and more uncertain.
- At the time of birth is 30 mg/dL and the range is 75 to 150 mg/dL.
- In infants from 30 days to 90 days, CSF protein is 20 to 100 mg/dL.
- The range from 90 days to 6 months is 15 to 50 mg/dL. The values slowly decline and reach the adult level by six months of age.
|Age of the patient||Amount of total protein|
|Infants||30 to 200 mg/dL|
|Child||14 to 45 mg/dL|
|Adult||15 to 45 mg/dL|
|Elderly||15 to 60 mg/dL|
Gamma globulin (CSF):
- It is 3 to 12 % of the total protein.
- It is from 120 to 130 meq/L.
- It is 20 meq higher than the serum.
- It is 15 to 17 units/L
- It is negative.
Normal Cerebrospinal Fluid Analysis (CSF) findings and normal range from various sources:
|Lab findings||Source 2||Source 1||Source 4|
|Pressure||<20 cm H2O||
|Appearance||Clear and colorless, no clot||Crystal clear and colorless||Clear and colorless|
|White cell count||
|Neutrophils||0 to 6%||
|Lymphocytes||40 to 80%||
|Monocytes||15 to 45%||
||Adult = 15 to 45 mg/dL|
|Cisternal area||15 to 25 mg/dL||Adult = 15 to 45 mg/dL = lumbar|
|Ventricular area||5 to 15 mg/dL||Adult = 5 to 15 mg/dL|
|Prealbumin||2 to 7%||2 to 7%|
|Albumin||56 to 76%||10 to 35 mg/dL||56 to 76%|
|Alpha1 globulin||2 to 7%||2 to 7%|
|Alpha2 globulin||4 to 12%||4 to 12%|
|Beta globulin||8 to 18%||8 to 18%|
|Gamma globulin||3 to 12%||3 to 12%|
|IgG||0 to 4.5 mg/dL||<4.0 mg/dL|
|Glucose||50 to 75 mg/dL (60 to 70% of blood glucose)||
|Sodium||135 to 160 meq/L|
|Potassium||2.6 to 3.0 meq/L|
|Chloride||700 to 750 mg/dL||115 to 130 meq/L||
|LDH||<2 to 7.2 units/mL||<20 U/L||Adult = <20 U/L (around 10% of serum)|
|Lactic acid||10 to 25 mg/dL||10 to 24 mg/dL||
|Glutamine||6 to 15 mg/dL||
|Urea nitrogen||6 to 16 mg/dL|
|Phosphorus||1.2 to 2.0 mg/dL|
|Creatinine||0.5 to 1.2 mg/dL|
|Uric acid||0.5 to 4.5 mg/dL|
|Ammonia||10 to 35 µg/dL|
|CSF cytology for malignancy||Negative||Negative||Negative|
Normal CSF summary:
|Total cell count|
|Adult and children||0 to 6/cmm, all are mononuclear|
|Glucose (Lumbar area)||
|Ventricular area||5 to 15 mg/dL|
|Cisternal area||15 to 25 mg/dL|
|IgG||<4.0 mg/dL (<10% of total CSF proteins)|
|Chloride||120 to 130 m eq/L (20 meq/L > than serum value)|
|Sodium||142 to 150 meq/L|
|Potassium||2.2 to 3.3 meq/L|
|pH||7.35 to 7.40|
|AST (SGOT)||7 to 49 units|
|Urea nitrogen||5 to 25 mg/dL|
|Creatine kinase (CK)||0 to 5 IU/L|
|Lactate dehydrogenase (LDH)||∼10% of the serum level|
|IgG||<4.0 mg/dL (<10% of the total CSF proteins)|
These lab summares are excellent. Thank you for providing refresher information. Very informative and helpful.
Thanks for the encouraging comments.