Measurement of cystatin C in cerebrospinal fluid.

Cyctatin C(CysC), a cysteine proteinase inhibitor, is produced from most cells and exists in various body fluids. We measured CysC concentrations in cerebrospinal fluid(CSF) using the same assay method as for serum CysC measurement. CSF-CysC concentrations in subjects without apparent disorders ranged from 1.8 to 7.2 mg/l(2SD) with a mean of 3.6 mg/l. Because serum CysC concentrations are less than 1 mg/l, CSF-CysC may preferably represent those produced in central nervous system. CysC was measured in CSF samples obtained in a hospital laboratory and their clinical information was retrospectively viewed. Generally, none of various disease groups, including infection, neoplasma, and vascular diseases had CysC values significantly different from the normal reference values. Subjects undergoing surgery and with hydrocephalus had varied CysC values, raising the possibility that CysC values may change under the influence of CSF flow.