Oxidative stress is a leading factor in the pathogenesis of idiopathic Parkinson disease (IPD). Two intrinsic antioxidative molecules, bilirubin and uric acid, are known to protect dopaminergic neurons from oxidative stress in IPD. The objective of this study was to determine the relationship between basal serum levels of 2 molecules and dopaminergic deficit assessed by dopamine transporter imaging with 18F-fluorinated-N-3-fluoropropyl-2-β-carboxymethoxy-3-β-(4-iodophenyl)nortropane ([18F]FP-CIT) PET/CT in patients with early-stage drug-naive IPD.
Cases of IPD patients who possess the levels of uric acid and bilirubin within a month from [18F]FP-CIT PET/CT from January 2011 to December 2016 were retrospectively reviewed. As a control, the same criteria applied to patients with essential tremor (ET). PET images were analyzed using volume-of-interest templates for 12 striatal subregions and 1 occipital area, and the specific-to-nonspecific binding ratio (SNBR) was calculated.
One hundred five patients with drug-naive, early-stage IPD and 62 patients with ET were finally included. Levels of bilirubin were significantly higher in the IPD group than in controls (P = 0.026), and bilirubin level was the factor showing the most correlations with SNBR in IPD (P < 0.001), whereas uric acid showed no such difference or relationship. Furthermore, levels of bilirubin showed a positive correlation with SNBR in more affected posterior putamen in the IPD group (Pearson correlation coefficient, ρ = 0.456; P < 0.001), but a negative one in the ET group (ρ = −0.440, P < 0.001).
Bilirubin, not uric acid, was the most significant antioxidant marker for dopaminergic deficit in early-stage drug-naive IPD assessed by [18F]FP-CIT PET/CT.
From the Departments of *Nuclear Medicine
†Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Received for publication March 18, 2019; revision accepted June 8, 2019.
Conflicts of interest and sources of funding: This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health & Welfare, Republic of Korea (grant HI14C2768 & HR18C2383). None declared to all authors.
Correspondence to: Jae Seung Kim, MD, PhD, Department of Nuclear Medicine, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea. E-mail: email@example.com.
Online date: September 5, 2019