Thyroid dysfunction in Portuguese amyotrophic lateral sclerosis patients

Introduction Thyroid hormones influence neuromuscular function, and it has been thought that this might contribute to degeneration of motor neurons. Methods We used case-control methods to investigate the prevalence of thyroid dysfunction (hyperthyroidism and hypothyroidism) in ALS patients followed in our centre, between 2015 and 2020. Data from patients with neuromuscular disorders not derived from thyroid dysfunction, followed within the same time frame, were used as controls. Thyroid dysfunction was defined by previous thyroid replacement medication managed by an endocrinologist. We used odds ratios (OR) with a 95% confidence interval (CI) to compare 579 ALS patients and 415 age-gender-matched disease controls. Additionally, we provide a summarized review of the literature. Results Hypothyroidism (prevalence of 5.0 versus 8.6%; OR = 0.56, 95% CI 0.34–0.92, p = 0.023), hyperthyroidism (prevalence of 0.3 versus 1.2%; OR = 0.28, 95% CI 0.06–1.47, p = 0.134) and overall thyroid dysfunction (prevalence of 5.4 versus 9.9%; OR = 0.52, 95% CI 0.32–0.84, p = 0.015) were less prevalent in ALS patients than in controls, but similar to the national epidemiological data for thyroid disease. Our data are in line with the findings of most previous studies. Conclusions We conclude that thyroid dysfunction is not associated with ALS.