What is the target Thyroid-Stimulating Hormone (TSH) level for patients with hypothyroidism?

Target TSH Levels for Hypothyroidism Management

For patients with hypothyroidism, the target TSH level should be between 0.5-2.0 mIU/L for most adults. 1

General TSH Targets by Patient Population

• For most adults with primary hypothyroidism, aim for a TSH between 0.5-2.0 mIU/L to normalize thyroid function and relieve symptoms 1, 2
• For elderly patients (>70 years), a higher TSH target is appropriate, with the upper limit of normal increasing with age - up to 7.5 mIU/L may be acceptable for patients over 80 years 3
• For pregnant women, maintain TSH in the trimester-specific reference range to prevent pregnancy complications and ensure proper fetal development 4, 2
• For patients with thyroid cancer requiring TSH suppression, lower targets may be indicated (0.1-0.5 mIU/L or <0.1 mIU/L depending on cancer status) 1

Treatment Approach Based on TSH Levels

• For TSH >10 mIU/L (with normal or low T4): Initiate levothyroxine therapy regardless of symptoms 1, 2
• For TSH between 4.5-10 mIU/L (with normal T4): Treatment decisions should be individualized based on:
  • Presence of symptoms 1, 5
  • Positive TPO antibodies 1
  • Pregnancy or planning pregnancy 1, 4
  • Presence of goiter 2

Monitoring and Dose Adjustments

• After initiating treatment or changing dose, recheck TSH in 6-8 weeks to evaluate response 1
• Once stable, monitor TSH every 6-12 months or sooner if symptoms change 1
• For patients with persistently elevated TSH despite adequate levothyroxine dosing, evaluate for poor compliance, malabsorption, or drug interactions 2, 6
• About 25% of patients on levothyroxine are unintentionally maintained on doses sufficient to fully suppress TSH, highlighting the importance of regular monitoring 1

Special Considerations

• For women who become pregnant while on levothyroxine, increase weekly dosage by 30% (take one extra dose twice weekly) and monitor monthly 4, 7
• For patients with cardiac disease or multiple comorbidities, start with lower doses (25-50 mcg/day) and titrate gradually 1, 4
• Avoid excessive dose increases that could lead to iatrogenic hyperthyroidism, which increases risk for osteoporosis, fractures, and cardiac complications 1

Common Pitfalls to Avoid

• Failing to confirm elevated TSH with repeat testing after 3-6 months, as 30-60% of high TSH levels normalize on repeat testing 1, 5
• Overtreatment leading to subclinical hyperthyroidism in 14-21% of treated patients 1, 5
• Undertreatment resulting in persistent hypothyroid symptoms, adverse effects on cardiovascular function, lipid metabolism, and quality of life 1
• Ignoring age-specific TSH targets, especially in elderly patients where aggressive normalization may be harmful 3

Evidence Quality and Limitations

• The evidence supporting treatment for subclinical hypothyroidism with TSH >10 mIU/L is rated as "fair" by expert panels 1
• Double-blinded randomized controlled trials show that treatment does not improve symptoms or cognitive function if TSH is less than 10 mIU/L in most patients 3
• Treatment may be harmful in elderly patients with subclinical hypothyroidism 3

By maintaining TSH within appropriate target ranges based on patient characteristics, clinicians can optimize treatment outcomes while minimizing potential adverse effects of both under- and over-treatment.