The Relationship of Thyroid Hormone Levels and Motor Symptoms in Parkinson's Disease

Aim: This study aimed to investigate the relationship between thyroid hormone levels and the motor symptoms of Parkinson's patients. Material and Methods: Neurology clinic logs of the patients diagnosed with Parkinson's disease and whose thyroid function tests were measured between 01.01.2018 and 01.04.2021 were selected. Those with primary thyroid hormone disorder were excluded. Motor symptom stages were determined according to the modified Hoehn and Yahr scale (mHYS) by records. According to the thyroid function test results, whether there was a difference in motor symptoms, duration of the disease, and effects of the drugs were examined. Results: Of the 93 patients included in the study, 53 (57.0%) were male and 40 (43.0%) were female. The median age of the patients was 71 years. The motor symptoms of the patients were classified as stage 1 in 21 (22.6%), stage 1.5 in 18 (19.4%), stage 2 in 29 (31.2%), stage 2.5 in 13 (14.0%), stage 3 in 4 (4.3%), stage 4 in 6 (6.5%), and stage 5 in 2 (2.2%) patients. The median levels of TSH, fT3, and fT4 were 2.075 uIU/ml, 2.925 ng/dl, and 1.235 ng/dl, respectively. There was no significant correlation between the mHYS stages of the patients and TSH (r=-0.148, p=0.164), fT3 (r=-0.073, p=0.623), and fT4 levels (r=0.075, p=0.491). Conclusion: There was no relationship between the severity of motor symptoms and hormone levels in patients with normal thyroid functions. Thyroid dysfunction may mimic many motor findings, but they do not affect the severity of motor findings in Parkinson's patients.