NeurologyNeurology

CSF Biochemical Analysis

Normal Range
Protein: 15-45 mg/dL; Glucose: 40-70 mg/dL
Sample Type
Cerebrospinal Fluid
Fasting
No
Unit
mg/dL

Function

Cerebrospinal fluid (CSF) is a clear, colorless liquid that bathes the brain and spinal cord, providing mechanical protection and immunological stability. Biochemical analysis of CSF typically involves measuring protein and glucose levels, as well as electrolytes like chloride. These parameters are tightly regulated by the blood-brain barrier (BBB).

Why it is Ordered

This analysis is a critical diagnostic tool for central nervous system (CNS) disorders. It is primarily ordered when a clinician suspects meningitis (bacterial, viral, or fungal), encephalitis, or a subarachnoid hemorrhage. It is also used in the diagnosis of autoimmune conditions like Multiple Sclerosis (MS) or inflammatory polyneuropathies like Guillain-Barré syndrome.

Associated Conditions

  • Bacterial Meningitis: Characterized by very high protein levels, low glucose (as bacteria consume it), and elevated white cell counts.
  • Multiple Sclerosis: May show mildly elevated protein and the presence of oligoclonal bands (detected via electrophoresis).
  • Subarachnoid Hemorrhage: Indicated by the presence of blood or xanthochromia (yellow tint from hemoglobin breakdown) in the fluid.
  • Viral Infections: Usually show moderately elevated protein but normal glucose levels.

Diagnostic Precision

The relationship between serum glucose and CSF glucose is vital. Normally, CSF glucose is about 60-70% of the blood glucose level. Therefore, a blood glucose sample should ideally be drawn shortly before the lumbar puncture for accurate comparison.

Panel Components

This test is a profile comprising the following specific markers:

CSF Albumin
mg/dL
CSF Glucose
mg/dL
CSF Lactate
mmol/L
CSF Appearance
N/A
CSF Total Protein
mg/dL
CSF Chloride
mmol/L
CSF Lactate Dehydrogenase (LDH)
U/L

Why Context Matters

CSF analysis can be compromised by a 'traumatic tap,' where blood from the needle insertion site contaminates the sample, artificially elevating protein and red cell counts. Additionally, timing is critical; if the sample is not transported to the lab and processed immediately, glucose levels will drop as cells in the fluid continue to metabolize the sugar, leading to a false diagnosis of bacterial infection.

Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.

Clinical References

Source-of-truth databases and clinical guidelines for CSF Biochemical Analysis:

Research & Guidelines

Related Indicators

CSF Lactate Dehydrogenase (LDH)

View Range

CSF Appearance

View Range

CSF Glucose

View Range
DR

Medically Reviewed by Dr. Binoy Babu, MBBS

Board Certified Doctor • 10+ Years Clinical Experience

Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.

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