<prompt> Presence of which of the following is confirmatory for CSF rhinorrhea?Glucoseb2 transferrinb trace proteina fetoprotein  <response>: Ans. is b i.e., b2 transferrin Detection of CSF Leak1 Biochemical tests Concentrations of Glucose are higher in CSF than in nasal discharge. Glucose value 30-40 mg and protein value 100 mg max 200 mg support a diagnosis of CSF leak. Presence of b2 transferrin is the most definitive test for detection of CSF and b2 transferrin assay is the test of choice when a confirmatory test is needed, because of high sensitivity as well as specificity. b-trace protein prostaglandin D synthase is also used, however it is nonspecific as it is also present in human testes, heart and seroma.2 Basic clinical tests Tissue test Handker chief test: - Unlike nasal mucous, CSF does not cause a tissue to stiffen. Filter paper test: - Sample of nasal discharge on a filter paper exhibits a light CSF border and a dark central area of blood, i.e., double ring sign or halo sign. Queckensted test: - Compression of the jugular vein leas to increased CSF leak due to increase in ICP. Rhinoscopy: - Visualization of CSF leak from paranasal sinus.3 CSF tracers Intrathecal fluorescein dye adminstration, radionuclide cisternography, CT cisternography. 