<prompt> Diagnostic test for CSF rhinorrhea is ?Beta - 2 microglobulinBeta - 2 transferrinThyroglobulinTransthyretin  <response>: Ans. is b i.e., Beta-2 transferrin Beta-2 transferrin is a CSF-specific variant of transferrin and is used as an endogenous marker of CSF leakage. Beta-2 transferrin is formed by loss of sialic acid due to the presence of neuraminidase in the central nervous system. Beta-2 transferrin has also been called CSF-specific transferrin and tau protein. 