Ataxia associated with Hashimoto’s thyroiditis autoantibodies has been reported as acquired cerebellar ataxia. However, relationship between anti-thyroid antibodies and cerebellar ataxia has not been clarified yet.

We aimed to analysis the relibility of serum anti-thyroid antibodies screening in the diagnosis of Parkinson’s disease (PD) and multiple system atrophy (MSA).

We enrolled 105 patients with clinically diagnosed PD and 75 patients with probable MSA. Patients with PD were classified into 70 patients with early PD (Hoehn & Yahr stage I to II) and 35 patients with late PD (Hoehn & Yahr stage III to IV). In MSA, 28 patients were classified as MSA-p (parkinsonism predominant) and 47 MSA-c (cerebellar predominant). For analysis of thyroid function, serum free triiodothyronine (T3), free thyroxine (T4), anti-thyroglobuline (TG) antibodies and anti-microsomal antibodies were measured. Cut-off level for abnormal titers of anti-thyroid antibodies were defiend as above 100 U/ml.

Abnormally high titer of serum anti-TG antibodies and anti-microsomal antibodies was more frequently observed in MSA than in PD (p =0.001 and 0.003, respectively). However, there was no significant difference in the frequency of abnormal titer either between MSA-c and MSA-p (p>0.05) nor between early PD and late PD (p>0.05). Among clinical parameters, only ataxia was correlated with both titer of anti-TG antibody and anti-microsomal antibody (p=0.007 and 0.002, respectively).

These results suggest that high titer of anti-thyroid antibodies may be associated with MSA rather than PD and screening of serum anti-thyroid antibodies may be helpful for discrimiation of PD from MSA. However, anti-thyroid antibodies screening may not be helpful to differentiate MSA-c from MSA-p.