Background and purpose
There is sufficient evidence to support vitamin D's noncalcemic effects and the role of vitamin D deficiency in the development of a wide range of neurological disorders. This study aimed to evaluate whether serum 25(OH)D and 1,25(OH) 2 D could be used as biomarkers to differentiate between healthy subjects (HS), multiple system atrophy (MSA) and Parkinson's disease (PD) patients of both genders.
Methods
A total of 107 subjects were included in this study, divided into three groups: 1- HS (
n
= 61), 2- MSA patients (
n
= 19), and 3- PD patients (
n
= 27). The patients were assessed using UMSARS II, UPDRS III, H&Y, MMSE and MoCA rating scales. The levels of 25(OH)D and 1,25(OH) 2 D in serum were determined using the radioimmunoassay technique.
Results
The levels of 25(OH)D and 1,25(OH) 2 D in HS were 26.85 +/− 7.62 ng/mL and 53.63 +/− 13.66 pg/mL respectively. 25(OH)D levels were lower in both MSA and PD by 61% and 50%, respectively (
P
= 0.0001 vs. HS). 1,25(OH) 2 D levels were lower in MSA by 29%(
P
= 0.001 vs HS). There was a correlation between 25(OH)D and 1,25(OH) 2 D in MSA and PD, but not in HS. 1,25(OH) 2 D regressed with MMSE (β = 0.476,
P
= 0.04, R 2 = 0.226) in MSA, and with UPDRS III (β = −0.432,
P
= 0.024, R 2 = 0.187) and MoCA (β = 0.582,
P
= 0.005,R 2 = 0.279) in PD. 25(OH)D displayed considerable differentiative strength between HS and MSA (Wald = 17.123, OR = 0.586,
P
= 0.0001; AUC = 0.982, sensitivity and Youden index = 0.882,
P
= 0.0001) and PD (Wald = 18.552, OR = 0.700,
P
= 0.0001; AUC = 0.943, sensitivity = 0.889, YI = 0.791,
P
= 0.0001). 1,25(OH) 2 D distinguished MSA from PD (Wald 16.178, OR = 1.117, P = 0.0001; AUC = 0.868, sensitivity = 0.926, Youden index =0.632, P = 0.0001). H&Y exhibited the highest sensitivity, AUC, and significant distinguishing power between MSA and PD.
Conclusions
Serum 25(OH)D and 1,25(OH) 2 D could be useful biomarkers for MSA and PD. 25(OH)D and H&Y provided the highest sensitivity and group classification characteristics.