BACKGROUND: Pediatric autoimmune neuropsychiatric disorders associated with 
streptococcal infections (PANDAS) are immune-mediated diseases characterized by 
obsessive-compulsive symptoms and/or tics triggered by group A Streptococcus 
infections. Despite the well-known action of 25-hydroxyvitamin D [25(OH)D] on 
different conditions driven by systemic inflammation, there are no data about 
the 25(OH)D status in patients with PANDAS.
AIMS: To evaluate plasma 25(OH)D levels in a large cohort of children and 
adolescents with PANDAS and comparing the results with healthy controls.
METHODS: We have evaluated plasma 25(OH)D levels in 179 Italian patients with 
PANDAS (49 females, 130 males, mean age at diagnosis: 101.4 ± 30.1 months) and 
in an age-, gender-, and body mass index-matched control group of 224 healthy 
subjects.
RESULTS: Patients with PANDAS have shown more frequently reduced 25(OH)D levels 
(<30 ng/mL) in comparison with controls (94.6% vs. 82.5%, p = 0.0007). Patients 
with PANDAS had also lower levels of 25(OH)D than controls (20.4 ± 6.9 ng/mL vs. 
24.8 ± 7.3 ng/mL, p < 0.0001). This difference was observed during both winter 
(13.7 ± 3.25 ng/mL vs. 21.4 ± 5.9 ng/mL, p < 0.0001) and summer 
(21.8 ± 6.5 ng/mL vs. 32.5 ± 8.7 ng/mL, p < 0.0001). Notably, serum 25(OH)D 
levels correlated with both number of streptococcal (strep) infections before 
diagnosis of PANDAS (p < 0.005) and with infection recurrence (p < 0.005).
CONCLUSIONS: PANDAS patients have reduced 25(OH)D levels, which appear related 
to streptococcal infections and the probability of recurrence. Further long-term 
studies with higher number of patients are needed to investigate and confirm 
this relationship.