Detailed definition
Subclinical hypothyroidism is defined biochemically by elevated TSH (above the upper reference limit, typically 4.5 mIU/L) with a normal free T4. Prevalence rises with age and is higher in women. Some patients are asymptomatic; others have nonspecific symptoms (fatigue, mood, cognitive). The decision to treat with levothyroxine depends on TSH level, symptoms, age, antibody status (anti-TPO positive cases progress more often to overt hypothyroidism), pregnancy status, and cardiovascular risk factors. ATA and Endocrine Society guidelines generally recommend treatment when TSH is persistently >10 mIU/L; below that threshold, treatment is individualized.
Why it matters in menopause
For midlife women presenting with menopause-like symptoms and TSH between 4.5 and 10 mIU/L, the decision to treat thyroid is nuanced. Some women feel meaningfully better on low-dose levothyroxine; others do not. A trial is reasonable when symptoms are significant.
Related terms
Sources
External references: Wikipedia.