What are the implications of an elevated Thyroid-Stimulating Hormone (TSH) level?

From the Guidelines

Elevated TSH levels should be treated with levothyroxine if confirmed by additional testing, with a typical starting dose of 1.6 mcg/kg/day, to improve symptoms and quality of life, as recommended by the USPSTF 1. The treatment of elevated TSH levels is crucial to prevent the progression of hypothyroidism and its associated symptoms, such as fatigue, cold intolerance, weight gain, dry skin, and constipation.

Key Considerations

• The serum TSH test is the primary screening test for thyroid dysfunction, and multiple tests should be done over a 3- to 6-month interval to confirm or rule out abnormal findings 1.
• The principal treatment for hypothyroidism is oral T4 monotherapy (levothyroxine sodium), and treatment is generally recommended for patients with a TSH level that is elevated, as it can improve symptoms and quality of life 1.
• Follow-up TSH testing is recommended after 6-8 weeks to adjust dosing as needed, with a target TSH of 0.5-4.0 mIU/L for most adults, to ensure optimal thyroid hormone levels 1.

Risk Factors

• Risk factors for an elevated TSH level include female sex, advancing age, white race, type 1 diabetes, Down syndrome, family history of thyroid disease, goiter, previous hyperthyroidism, and external-beam radiation in the head and neck area 1.
• The most common cause of hypothyroidism in the United States is chronic autoimmune (Hashimoto) thyroiditis, and clinicians seem to be treating more persons with thyroid dysfunction, at earlier times after initial diagnosis, and at TSH levels closer to normal 1.

From the FDA Drug Label

• Hypothyroidism: As replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism • Adequacy of therapy determined with periodic monitoring of TSH and/or T4 as well as clinical status.

Elevated TSH is an indication of hypothyroidism, which can be treated with levothyroxine sodium tablets. The goal of treatment is to normalize TSH levels.

• The dosage of levothyroxine sodium should be adjusted based on periodic monitoring of TSH and/or T4 levels, as well as clinical status.
• It is essential to titrate the dose carefully and monitor response to titration to avoid overtreatment or undertreatment 2.

From the Research

Elevated TSH: Diagnosis and Treatment

• Elevated TSH levels can indicate hypothyroidism, a common disorder characterized by inadequate thyroid hormone secretion 3.
• The symptoms of hypothyroidism include slow metabolism, constipation, fatigue, sensitivity to cold, weight gain, and polysaccharide accumulation in certain tissues, leading to hoarseness and eyelid swelling 3.
• A blood TSH concentration of less than 4 or 5 mlU/L rules out peripheral hypothyroidism, while TSH levels increase with age 3.

Subclinical Hypothyroidism

• Subclinical hypothyroidism is characterized by high blood TSH levels and normal free T4 levels, and is rarely symptomatic 3.
• The risk of progression to overt hypothyroidism is about 3% to 4% per year overall, but increases with the initial TSH level 3.
• Treatment guidelines recommend levothyroxine therapy, but the decision to treat subclinical hypothyroidism should be based on individual patient factors, such as age and symptoms 4, 5.
• Some studies suggest that treatment may not be necessary unless the TSH exceeds 7.0-10 mIU/L, and that cardiovascular events may be reduced in patients under age 65 with subclinical hypothyroidism who are treated with levothyroxine 5.

Levothyroxine Treatment

• Levothyroxine is the standard treatment for hypothyroidism, and the goal of treatment is to achieve a normal serum TSH level 3, 6.
• The adverse effects of levothyroxine include signs of thyrotoxicosis in case of overdose, such as tachycardia, tremor, and sweating, as well as osteoporotic fractures and atrial fibrillation, especially in the elderly 3.
• The dose of levothyroxine should be adjusted based on blood TSH assay, and certain drugs, such as iron and calcium, can reduce the gastrointestinal absorption of levothyroxine 3.

Alternative Treatments

• Some patients with persistent symptoms despite levothyroxine treatment may benefit from combined treatment with levothyroxine and liothyronine, especially those with a polymorphism in type 2 deiodinase 4, 5, 7.
• However, current clinical evidence is not sufficiently strong to support LT4/LT3 combination therapy in patients with hypothyroidism, and persistent symptoms may be caused by other conditions unrelated to thyroid function 7.