Diagnostic Use
CSF protein measurement may help in the investigation of suspected inflammation/CSF of the central nervous system.
Note that this test is separate and distinct from CSF IgG oligoclonal band testing.
Interpretation
There are a number of factors that may affected the measured CSF protein concentration:
- Age: The reference interval of 0.15-0.45g/L was historically derived from small studies which involved mainly healthy young adults <30yrs of age. CSF protein is actually higher in newborns and it gradually decreases to close to adult levels by around 3- 6 months (95 th percentile for infants between 1-2 months is around 0.90g/L). From 40 years onwards, there is incremental rise in CSF protein. The estimated upper reference limits are : 0.57g/L at age 40; 0.59 g/L at age 50; 0.62g/L at age 60; and 0.66g/L at age 70. Although there is age related rise in CSF protein, in order to maintain sensitivity for CNS (central nervous system) pathological conditions, we prefer not to adopt age-adjusted upper reference limits as it is not uncommon to observe CSF proteins in the range between 0.45g/L and age-related upper reference limits in different CNS diseases.
- Site of collection – Lumbar region-derived CSF has higher protein content than CSF from brain ventricles. CSF albumin (normally account for at least 50% of CSF protein) positively varies with body mass index or abdominal circumference. The hypothesis is that in obesity, there is increase in venous pressure causing mild impairment in rate of CSF reabsorption from subarachnoid space.
- Blood contamination – While some formula using RBC count to correct for plasma protein contribution exist, they are generally inaccurate and use is discouraged. CSF protein in subarachnoid haemorrhage is usually ~2.0g/L.
Albumino-cytologic dissociation (ACD) (or protein cell dissociation) refers to elevated CSF protein without pleocytosis. It can occur in Guillain-Barre syndrome, Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) or epileptic seizures. ACD, especially with very high protein content, is typically observed in spinal stenosis or compression arising from e.g. trauma, tumour, disc herniation or abscess (part of Froin syndrome).
Reference Intervals
For lumbar puncture specimens. Lower values will be found in CSF from other sites.
Units: g/L
| Baby:
Premature:
|
0.15 – 1.3
|
|
Full Term:
|
0.40 – 1.2
|
|
Child and Adult:
|
0.15 – 0.45
|
- Blood contamination can cause false elevations of “CSF protein”
Test Method
Performed in: LabPlus Automation
Principle: Immunoturbidometric assay
Reagents: Roche assay
Analyser: Roche Cobas