From the Guidelines
Graves' disease can increase the risk of developing Myasthenia Gravis (MG) due to the shared autoimmune mechanism. Both conditions are distinct autoimmune diseases that can occur together in the same patient more frequently than would be expected by chance, suggesting a shared underlying immune system dysregulation 1. The connection between the two conditions likely stems from the involvement of autoantibody production, with antibodies targeting thyroid receptors in Graves' disease and acetylcholine receptors at neuromuscular junctions in myasthenia gravis.
Key Points to Consider
- The presence of autoimmune thyroid disease, such as Graves' disease, increases the risk for myasthenia gravis 1.
- Hyperthyroidism from Graves' disease can worsen myasthenia gravis symptoms, making proper management of thyroid function essential in patients with both conditions.
- Treatment typically involves addressing both conditions separately, with antithyroid medications for Graves' disease and acetylcholinesterase inhibitors for myasthenia gravis.
- Patients with both conditions require careful monitoring as treatments for one condition may impact the other.
Management and Treatment
The goal of treatment is to manage both conditions effectively, reducing morbidity and mortality, and improving quality of life. Proper management of thyroid function is crucial in patients with both Graves' disease and myasthenia gravis. This may involve the use of antithyroid medications like methimazole for Graves' disease, and acetylcholinesterase inhibitors like pyridostigmine for myasthenia gravis. Regular monitoring and adjustments to treatment plans are necessary to ensure optimal outcomes for patients with both conditions.
From the Research
Association between Graves' disease and Myasthenia Gravis
- Graves' disease and Myasthenia Gravis (MG) are two autoimmune diseases that can coexist in some patients 2, 3, 4, 5, 6.
- The relationship between these two entities has remained controversial, with some authors reporting a see-saw relationship between them, where MG wanes with hyperthyroidism and waxes with treatment of hyperthyroidism 2, 3.
- Treatment of both disorders concurrently can be challenging, as treatment for one entity may worsen the other 2, 3.
- The use of beta-blockers and steroids for Graves' disease may worsen myasthenic weakness, while antithyroid drugs can worsen myasthenia probably by immunomodulatory effects 2.
Clinical Features and Diagnosis
- Myasthenia Gravis and Graves' disease can have similar clinical features, leading to difficulty in distinguishing between the two conditions 3, 5, 6.
- The overlapping clinical features may cause diagnostic confusion when myasthenia gravis and Graves' disease coexist, and numerous tests may be needed to distinguish these two conditions 5.
- A high degree of clinical vigilance is necessary to appreciate the presence of both conditions, especially in cases where ocular myasthenia can be easily missed in patients with Graves' disease 6.
Pathogenesis and Association
- Recent research has shown the involvement of autoantibodies, lymphocytes, cytokines, and chemokines in the pathogenesis of MG and GD 4.
- The Th17 cell lineage is involved in autoimmune thyroid disease (AITD) and seems to be a key factor in the development of both MG and GD 4.
- The coexistence of GD and MG may be due to shared pathogenetic mechanisms, and further studies are needed to establish an association between the two pathologies 3, 4.