Adult CSF total protein: Higher upper reference limits should be considered worldwide. A web-based survey

Area of Science:

• Neurology
• Clinical Chemistry
• Laboratory Medicine

Background:

• Cerebrospinal fluid total protein (CSF-TP) is a key marker for central and peripheral nervous system diseases.
• The widely used upper reference limit of 0.45 g/L for CSF-TP is increasingly recognized as an underestimation.
• Recent studies suggest higher CSF-TP values are appropriate, particularly with age adjustments.

Purpose of the Study:

• To assess current global practices regarding CSF-TP upper reference limits.
• To investigate the sources and age-dependency of these reference limits.
• To highlight discrepancies between current practices and recent scientific findings.

Main Methods:

• A global, web-based survey was distributed to laboratories.
• The survey included three questions on CSF-TP upper limits, their sources, and age adjustments.
• Data from 473 unique responses were analyzed.

Main Results:

• 86.8% of responding institutions use an upper CSF-TP limit of 0.45 g/L or lower.
• Only 4% of institutions reported using age-partitioned adjustments for CSF-TP.
• Responses were received from North America, South America, Europe, Africa, Asia, and Oceania.

Conclusions:

• A significant majority of global hospital laboratories utilize underestimated CSF-TP upper reference values.
• Current practices, especially for older adults, do not reflect updated scientific evidence.
• There is a need to update laboratory guidelines to incorporate age-adjusted CSF-TP reference values.