Subclinical Hypothyroidism

Subclinical hypothyroidism occurs in an asymptomatic patient with a TSH > 4 mU/L with normal T4 and T3.

Subclinical hypothyroidism is common in older patients. 10% of patients more than 55 years old have elevated TSH. The risk of progression to frank hypothyroidism is 2%. This risk increases in men and in those with anti-TPO antibodies.

• Treatment
  • Recheck TFTs q 2 – 4 months to confirm that raised TSH is persistent
  • Recheck history for any specific features, e.g., depression, which may benefit from treatment
  • Monitor TSH yearly
• Indications for levothyroxine
  • TSH ≥ 10 mU/L
  • Positive thyroid autoantibodies
  • History of treatment for Graves’ disease
  • Other organ-specific autoimmunity, e.g., T1DM, myasthenia gravis, vitiligo
• Complications of overtreatment
  • Atrial fibrillation
  • Osteoporosis