[New methods of diagnosing cerebrospinal fluid fistulas using beta 2-transferrin or prealbumin--principles and methodology].

Two new methods were developed to identify pure CSF and CSF in nasal secretion. One method is based on measurement of beta 2-transferrin, a transferrin variant found only in CSF, whereas the other one is based on determination of the albumin-prealbumin ratio. The determination of beta 2-transferrin is made in two steps. Firstly, the protein variants beta 1- and beta 2-transferrin are isolated selectively from the complex protein mixture by an affinity procedure. The transferrin variants are then separated by a highly resolving polyacrylamide gelelectrophoresis and identified by staining. Advantages of the method are that blood or nasal secretion does not disturb the test and that beta 2-transferrin can be identified with high accuracy. Therefore, CSF can be differentiated unambiguously from other secretions. The determination of the ratios of concentration of the proteins albumin and prealbumin by immunoelectrophoresis is a further possibility to identify pure or almost pure CSF. This sensitive method, which is fast and easy to perform, is very helpful in corroborating the diagnosis of a CSF fistula. On the basis of this method one cannot get a false positive result, but a false negative one by high contamination of CSF with blood or nasal secretion. Therefore, the method of beta 2-transferrin determination must be carried out if there is any doubt.