This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'All are helpful for the diagnosis of CSF rhinorrhea except: \nSelect and explain. \nA. High glucose, B. High protein, C. Tram line, D. Beta transferrin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Following trauma of the midface, CSF may emanate from a dural tear, resulting in rhinorrhea, otorrhea, or both.\xa0\nThe\xa0 disruption\xa0 usually\xa0 occurs\xa0 lateral\xa0 to\xa0 the\xa0 cribriform plate but may also result from disruption of the sphenoidal,\xa0 ethmoidal,\xa0 and\xa0 frontal\xa0 sinuses\xa0 producing\xa0 a\xa0 dural tear and communication with the subarachnoid space.\nDiagnosis\xa0of\xa0CSF\xa0leakage\xa0is\xa0often\xa0complicated\xa0by mixture\xa0with\xa0nasal\xa0secretions,\xa0lacrimal\xa0 secretions,\xa0and\xa0blood. Clear CSF should be collected in a vial, an absence of sediment and a glucose level of approximately 45 mg/dL is usually confirmatory.\xa0\nA more specific, albeit slower, laboratory examination is the CSF-specific beta-2 transferrin\xa0test.\nCSF\xa0 will\xa0 also\xa0 form\xa0 concentric\xa0 rings\xa0 when poured on linen or soft filter paper.\xa0\nCSF has a more rapid diffusion than blood, leading to a larger, clearer CSF ring surrounding a sanguineous central ring. This is termed the double-ring or halo sign. When bleeding is present, one should suspect the presence of a CSF leak until proven otherwise. Once a provisional diagnosis is made, the patient should be placed in a semirecumbent position and instructed on how to minimize increases in intracranial pressure, including straining, sneezing and blowing of the nose.\nMeningitis\xa0 is\xa0 a\xa0 potential\xa0 complication\xa0 of\xa0 skull\xa0 base fracture with a concomitant dural tear. The absence of\xa0leakage does not imply the absence of a tear.\xa0\nReference: Fonseca 4th ed page no 437,439', 'role': 'assistant'}]