Can hyperthyroidism (elevated thyroid hormone) cause recurrent illness?

From the Guidelines

Yes, elevated thyroid hormone levels (hyperthyroidism) can cause recurrent illness. When the thyroid produces excessive hormones, it creates a hypermetabolic state that affects multiple body systems, leading to recurring symptoms and health issues. Common recurrent problems include persistent fatigue, anxiety, heart palpitations, unexplained weight loss, heat intolerance, frequent bowel movements, and muscle weakness. Hyperthyroidism can also weaken the immune system, making individuals more susceptible to infections. Additionally, untreated hyperthyroidism may cause recurring episodes of thyroid storm, a life-threatening condition characterized by extreme symptoms requiring emergency care.

Key Considerations

• The USPSTF found no direct evidence that treatment of thyroid dysfunction based on risk level alters final health outcomes 1.
• Treatment typically involves anti-thyroid medications like methimazole (starting at 5-30mg daily) or propylthiouracil (50-300mg daily in divided doses), beta-blockers such as propranolol (10-40mg three to four times daily) to manage symptoms, radioactive iodine therapy, or in some cases, thyroid surgery.
• The underlying cause of hyperthyroidism, such as Graves' disease or toxic nodular goiter, must be identified and addressed to prevent recurrent illness.
• Regular monitoring of thyroid function through blood tests is essential during and after treatment to maintain proper hormone levels.

Important Factors

• Risk factors for a low TSH level include female sex; advancing age; black race; low iodine intake; personal or family history of thyroid disease; and ingestion of iodine-containing drugs, such as amiodarone 1.
• The serum TSH test is the primary screening test for thyroid dysfunction, with multiple tests done over a 3- to 6-month interval to confirm or rule out abnormal findings 1.
• Follow-up testing of serum T4 levels in persons with persistently abnormal TSH levels can differentiate between subclinical (normal T4 levels) and “overt” (abnormal T4 levels) thyroid dysfunction.

From the Research

Elevated Thyroid Hormone and Recurrent Illness

• Elevated thyroid hormone, also known as hyperthyroidism, can lead to various health issues, including recurrent illness 2, 3, 4, 5.
• Hyperthyroidism can cause an excessive concentration of thyroid hormones in tissues, leading to increased synthesis of thyroid hormones, excessive release of preformed thyroid hormones, or an endogenous or exogenous extrathyroidal source 3.
• The most common causes of hyperthyroidism are Graves' disease, toxic multinodular goiter, and toxic adenoma 2, 3, 4, 5.
• If left untreated, hyperthyroidism can cause cardiac arrhythmias, heart failure, osteoporosis, and adverse pregnancy outcomes, and may lead to unintentional weight loss and increased mortality 5.
• Treatment options for hyperthyroidism include antithyroid drugs, radioactive iodine ablation, and surgery, and the choice of treatment depends on the underlying diagnosis, presence of contraindications, severity of hyperthyroidism, and patient preference 2, 3, 4, 5.

Risk of Recurrence

• Recurrence of hyperthyroidism after treatment is a significant concern, with approximately 50% of patients experiencing recurrence after a 12-18 month course of antithyroid drugs 2.
• Factors that increase the risk of recurrence include being younger than 40 years, having high FT4 concentrations, having high TSH-binding inhibitory immunoglobulins, and having a large goitre size before treatment 2.
• Long-term treatment with antithyroid drugs (5-10 years) can reduce the risk of recurrence to 15% compared to short-term treatment (12-18 months) 2.

Management and Treatment

• Management of hyperthyroidism involves treating the underlying cause, as well as managing symptoms and preventing complications 4, 5.
• Antithyroid medications can be used to temporarily treat thyrotoxicosis, while radioactive iodine or surgery can provide more definitive treatment 3, 4, 5.
• In some cases, patients may require ongoing treatment with antithyroid medications or other therapies to manage their condition 4, 5.