This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and PNS, Subject name: ENT
CSF rhinorrhoea is diagnosed by: 
Select and explain. 
A. b2 macroglobulin, B. b2 transferrin, C. Thyroglobulin, D. Transthyretin
B: b2 transferrin
Answer: B: b2 transferrin 
Explanation: (b) b2 transferrin(Ref. Cummings, 6th ed., 807)b2 transferrin on electrophoresis is pathognomonic of CSF as this protein is present only in CSF.