An international panel issues a strong recommendation against thyroid hormones in adults with subclinical hypothyroidism (SCH, elevated TSH levels and normal free T4
[thyroxine]
levels). It does not apply to women who are trying to become pregnant or patients with TSH >20 mIU/L. It may not apply to patients with severe symptoms or young adults (such as those ≤30 years old). In addition to the burden of lifelong management and uncertainty on potential harms, a systematic review of 21 trials with 2192 participants revealed that for adults with SCH, thyroid hormones consistently demonstrate no clinically relevant benefits for quality of life or thyroid related symptoms, including depressive symptoms, fatigue, and body mass index (moderate to high quality evidence). Thyroid hormones may have little or no effect on cardiovascular events or mortality (low quality evidence). The definition of SCH varies due to poor consensus about the cut-off level. TSH levels may increase with age, about 62% of TSH levels between 4 and 10 mIU/L normalize without intervention within 5 years. There is biological variation in TSH levels. Levels may rise in response to stress and transient disease. The risk of progression to overt hypothyroidism ranges between 2% and 5% a year. Presence of antibodies to thyroid peroxidase and, in particular, higher TSH levels increase this risk. Source: https://www.bmj.com/