The aim: To evaluate the testifying value of cystatin C in the diagnostics of some neurodegenerative diseases and its contribution to the diagnostics of these disorders. The group and methods: A set of 437 patients (212 men, 225 women, aged 5–92, mean age 62 + 14.73 years) was examined. The patients were divided into 9 subgroups: 1 – neurodegeneration (n = 43), 2 – Alzheimer’s dementia (n = 26), 3 – serous inflammation of the CNS (n = 33), 4 – bacterial inflammation of the CNS (n = 4), 5 – multiple sclerosis (n = 71), 6 – demyelinating neuropathy (n = 15), 7 – ischemic affection of the CNS (n = 41), 8 – hemorrhagic cerebrovascular accident (CVA) (n = 5), 9 – other diagnoses without the CNS affection (n = 196). Results: In neurodegenerative diseases there was only demonstrated the tendency to lower serum levels of cystatin C with respect to other groups (in AD it was 42.9 %) differing statistically significantly from serous inflammation of the CNS (dg. 3) where the proved levels were higher. The CSF cystathine C levels did not differ statistically among diagnostic groups. The cystatin C index showed higher levels in neurodegenerative disorders, particularly in dg. 2, which differs statistically significantly from dgs. 3, 6, and 7. Conclusions: The existence of decreased parameters of cystatin C in liquor and serum in neurodegenerative diseases presented in some earlier studies has not been sufficiently proved by our results. Statistically significantly higher levels of the cystatin C index in AD can be referred to as a certain testifying value for its differential diagnostics.

        Key words: cystatin C, biochemical diagnostics, neurodegenerative diseases, Alzheimer’s disease