To investigate the relationship between serum cystatin C and dopamine receptor(DAT) loss in patients with parkinson's disease(PD)

Number of people suffered from Parkinson disease (PD) is increasing every year. PET imaging of dopamine transport receptors（DAT） serves as the gold standard for the diagnosis and monitoring of PD development. However, due to high costs and radiation reasons, it is not suitable for long-term follow-up. Serum cystatin C can be easily obtained and cheap as an indicator. In recent years, studies have gradually found that it is related to the progression of H&Y staging of Parkinson's disease. To this extent, we want to further explore whether it can reflect the loss of DAT in the brain. Explore whether it can partially replace the role of DAT imaging for future clinical evaluation.

Inclusion Criteria:

• Patients aged between 20 and 80 years and whose laboratory results included the levels of serum Cystatin C within a month from the PET-DAT were recruited.

Exclusion Criteria:

• To make the study cohort more homogeneous, PD patients with either a long-standing duration (≥5 years) or advanced Hoehn and Yahr (H&Y) staging (≥3) were excluded.

Pearson correlation analysis is planned, and the sample size is calculated with PASS 15.0 software. 121 participants required after sample size calculation. The calculation parameters are as follows: Power = 0.90, α=0.05, ρ0 = 0.0, and ρ1 = 0.3.