Subcliniral hypothyroidism: When to treat, when to watch?

Before a diagnosis of subclinical hypothyroidism is made, other causes of elevated thyroid-stimulating hormone (TSH), such as recovery from a serious acute illness, must be ruled out. Diagnosis is based on at least 2 assays performed over a period of several weeks. If the screening TSH levels are abnormal, measurement of serum free thyroxine is needed to confirm the diagnosis. Although patients who have TSH levels in the upper limit of the traditional normal range may be at higher risk for progression to hypothyroidism, no evidence exists for adverse health consequences. For patients with serum TSH levels in the range of 5.1 to 10 mlU/L, consider such factors as age, comorbidities, symptoms of hypothyroidism, pregnancy or anticipation of pregnancy, and the presence of goiter or antithyroid antibodies in the decision to treat. Thyroxine therapy is recommended for patients with serum TSH levels above 10 mlU/L.