This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and paranasal sinuses, Subject name: ENT
CSF rhinorrhoea is diagnosed by which of the following? 
Select and explain. 
A. Beta 2 microglobulin, B. Beta 2 transferrin, C. Thyroglobulin, D. Transthyretin
B: Beta 2 transferrin
Answer: B: Beta 2 transferrin 
Explanation: Beta 2 transferrin is a protein seen in CSF and not in nasal discharge. Its presence is a sensitive and specific test for CSF. Another protein is beta-trace protein is also specific for CSF. (Ref: PL Dhingra, 7th edition of Diseases of Ear, Nose and Throat, pg no.184)