All are true regarding CSF Rhinorrhea Except

CSF RHINORRHOEALeakage of CSF into the nose is called CSF rhinorrhoea. It may be clear fluid or mixed with blood as in acute head injuries. DIAGNOSISThere is a history of clear watery discharge from the nose on bending the head or straining. It may be seen on rising in the morning when the patient bends his head (reservoir sign--fluid which had collected in the sinuses, paicularly sphenoid, empties into the nose). CSF rhinorrhoea should be differentiated from the nasal discharge of allergic or vasomotor rhinitis as the former is sudden, gushes in drops when bending and cannot be sniffed back. Nasal discharge, because of its mucus content, also stiffens the handkerchief.Differences between CSF and nasal secretionsFeaturesCSF fluidNasal secretionHistoryNasal or sinus surgery, head injury or an intracranial tumorSneezing, nasal stuffiness, itching in thenose or lacrimationFlow of dischargeA few drops or a stream of fluid gushes down whenbending forward or straining; cannot be sniffed backContinuous, no effect of bending forwardor straining. Can be sniffed backCharacter of dischargeThin, watery and clearSlimy (mucus) or clear (tears)TasteSweetSaltySugar contentMore than 30 mg/dL (Compare with sugar in CSF after lumbar puncture as sugar is less in CSF in meningitis.)Less than 10 mg/dLPresence of b2 transferrinAlways present. It is specific for CSFAlways absentRef: Dhingra; 6th edition; Page no: 164