Which statement best indicates disruption of the blood-brain barrier?

Which statement best indicates disruption of the blood-brain barrier?

• A. Decreased CSF albumin to serum albumin ratio
• B. Increased CSF albumin relative to serum albumin
• C. Increased CSF glucose
• D. Decreased CSF total protein

Answer: (B)

Disruption of the blood-brain barrier shows up when large proteins from the blood leak into the CSF. Albumin is a large plasma protein that normally does not cross an intact barrier, so when the barrier is compromised, CSF albumin rises relative to serum albumin. This makes the CSF albumin to serum albumin ratio a sensitive indicator of BBB permeability; an elevated ratio signals disruption. CSF glucose is largely governed by serum glucose and transporter activity, so barrier leakage doesn’t directly reflect permeability changes and can be normal or affected in other ways, such as in infection where glucose may drop due to consumption. Decreased CSF total protein would argue against disruption, since barrier breach typically allows more protein into CSF, not less. So the best indicator of BBB disruption among the options is an increase in CSF albumin relative to serum albumin.

Disruption of the blood-brain barrier shows up when large proteins from the blood leak into the CSF. Albumin is a large plasma protein that normally does not cross an intact barrier, so when the barrier is compromised, CSF albumin rises relative to serum albumin. This makes the CSF albumin to serum albumin ratio a sensitive indicator of BBB permeability; an elevated ratio signals disruption.

CSF glucose is largely governed by serum glucose and transporter activity, so barrier leakage doesn’t directly reflect permeability changes and can be normal or affected in other ways, such as in infection where glucose may drop due to consumption. Decreased CSF total protein would argue against disruption, since barrier breach typically allows more protein into CSF, not less.

So the best indicator of BBB disruption among the options is an increase in CSF albumin relative to serum albumin.