Parkinson's disease and thyroid dysfunction.

Background: Although no causal linkage between hypothyroidism and Parkinson's disease (PD) has been demonstrated so far, both share common manifestations and coexistence can be a source of diagnostic delay and confusion.

Purpose: To assess thyroid function in patients with PD.

Scope: Ninety-five PD patients and 102 age-matched controls were assessed for hypothyroidism through clinical evaluation and laboratory screening.

Results: In the PD group 13.7% were hypothyroid versus 10.8% in the control group. Statistical analysis did not show a significant difference (p = 0.3681).

Conclusion: Although hypothyroidism was not more prevalent in our PD patients in comparison with the control group, we believe that given the potential overlap of symptoms and signs, thyroid function should be assessed in patients showing worsening of symptoms that cannot be explained by disease progression or resistance to therapy adjustment; screening should take into account the particular acute effect of levodopa on serum TSH levels.