From the Guidelines
Treatment for subclinical hypothyroidism is not recommended for patients with TSH levels between 4.5 and 10.0 mIU/L, except in cases of pregnancy, planned pregnancy, or symptoms suggestive of hypothyroidism, due to the minimal consequences of the condition and insufficient evidence supporting treatment benefits. The decision to treat subclinical hypothyroidism should be based on individual factors, including the presence of symptoms, TSH levels, and specific patient populations such as pregnant women or those planning pregnancy 1. For patients with TSH levels above 10 mIU/L, levothyroxine replacement therapy is typically recommended, starting with a dose of 25-50 mcg daily for most adults, with adjustments made based on TSH levels measured 6-8 weeks after starting therapy 1.
Key Considerations
- Treatment is often considered for patients with symptoms suggestive of hypothyroidism, such as fatigue, cold intolerance, and mild cognitive impairment
- Pregnant women or those planning pregnancy with subclinical hypothyroidism may benefit from treatment to prevent adverse outcomes
- The goal of treatment is to achieve TSH levels within the normal range, typically 0.4-4.0 mIU/L
- Regular monitoring with TSH tests every 6-12 months is necessary to ensure proper dosing and adjust treatment as needed
Special Considerations
- Patients with TSH levels between 4.5 and 10.0 mIU/L may be considered for a trial of levothyroxine if they have symptoms compatible with hypothyroidism, but the likelihood of improvement is small and must be balanced against the potential risks and inconvenience of therapy 1
- The natural history of subclinical hypothyroidism and the risk of progression to overt hypothyroidism should be discussed with patients, particularly those with TSH levels above 10 mIU/L or specific risk factors.
From the FDA Drug Label
The levothyroxine in Levothyroxine Sodium Tablets, USP is intended to replace a hormone that is normally produced by your thyroid gland. The diagnosis of hypothyroidism is confirmed by measuring TSH levels using a sensitive assay (second generation assay sensitivity ≤ 0. 1 mlU/L or third generation assay sensitivity ≤ 0. 01 mlU/L) and measurement of free-T4.
The recommended treatment for subclinical hypothyroidism is levothyroxine replacement therapy. The goal of treatment is to achieve and maintain normal intellectual and physical growth and development.
- Key points:
- The diagnosis of hypothyroidism is confirmed by measuring TSH levels and free-T4.
- Levothyroxine is intended to replace a hormone that is normally produced by the thyroid gland.
- The adequacy of therapy is determined by periodic assessment of appropriate laboratory tests and clinical evaluation.
- The frequency of TSH monitoring during levothyroxine dose titration depends on the clinical situation but it is generally recommended at 6-8 week intervals until normalization 2, 2.
From the Research
Treatment for Subclinical Hypothyroidism
The treatment for subclinical hypothyroidism is a topic of ongoing debate, with various studies providing insights into the recommended approach.
- The decision to treat subclinical hypothyroidism depends on several factors, including the level of thyroid-stimulating hormone (TSH), the presence of symptoms, and the patient's age and cardiovascular risk factors 3, 4, 5, 6.
- Generally, treatment is not necessary unless the TSH exceeds 7.0-10 mIU/L, as treatment does not improve symptoms or cognitive function if the TSH is less than 10 mIU/L 3.
- For patients with TSH levels above 10 mIU/L, levothyroxine therapy is indicated, as it can help reduce the risk of cardiovascular disease and improve symptoms 4, 5.
- In patients with TSH levels between 4.0 and 10.0 mIU/L, the decision to treat should be individualized, taking into account the presence of symptoms, anti-thyroid antibodies, increased lipids, and other risk factors 4, 5.
- Some studies suggest that levothyroxine therapy may only provide benefit in certain subgroups, such as patients who are younger or at higher risk of cardiovascular disease 6.
- The use of levothyroxine in subclinical hypothyroidism to reduce cardiovascular disease risk is not clearly beneficial, and further study is recommended to determine the effects of treatment on cardiovascular outcomes 6.
- TSH goals are age-dependent, with a 97.5 percentile (upper limit of normal) of 3.6 mIU/L for patients under age 40, and 7.5 mIU/L for patients over age 80 3.
- In some cases, combined treatment with levothyroxine and liothyronine may be preferred, especially in patients with a polymorphism in type 2 deiodinase 3.