Which disorder is not associated with an elevated protein level in cerebrospinal fluid?

Which disorder is not associated with an elevated protein level in cerebrospinal fluid?

• A. Bacterial meningitis
• B. Multiple sclerosis
• C. Cerebral infarction
• D. Hyperthyroidism

Answer: (D)

CSF protein levels rise when the barrier between blood and brain is disrupted or when there is immune activity inside the central nervous system. In bacterial meningitis, the inflammation aggressively disrupts the blood-brain barrier, leading to markedly elevated CSF protein. Multiple sclerosis can show an increase in CSF protein as part of intrathecal immunoglobulin activity, although the hallmark diagnostic feature is oligoclonal bands rather than a large protein rise. Cerebral infarction damages brain tissue and the barrier, allowing protein to leak into the CSF, so a rise is possible there as well. Hyperthyroidism, however, does not typically involve processes that disrupt the blood-brain barrier or drive intrathecal immune responses, so CSF protein levels generally stay normal or only minimally affected. Therefore, hyperthyroidism is the disorder not associated with an elevated CSF protein level.

CSF protein levels rise when the barrier between blood and brain is disrupted or when there is immune activity inside the central nervous system. In bacterial meningitis, the inflammation aggressively disrupts the blood-brain barrier, leading to markedly elevated CSF protein. Multiple sclerosis can show an increase in CSF protein as part of intrathecal immunoglobulin activity, although the hallmark diagnostic feature is oligoclonal bands rather than a large protein rise. Cerebral infarction damages brain tissue and the barrier, allowing protein to leak into the CSF, so a rise is possible there as well. Hyperthyroidism, however, does not typically involve processes that disrupt the blood-brain barrier or drive intrathecal immune responses, so CSF protein levels generally stay normal or only minimally affected. Therefore, hyperthyroidism is the disorder not associated with an elevated CSF protein level.