Table 1.
Summary of Key Contents in Clinical Guidelines for Managing Subclinical Hypothyroidism
| Guidelines | Consideration of LT4 treatment | Observation without LT4 treatment |
|---|---|---|
| ATA (2012) [4] | TSH >10 mIU/L, age <70 years | TSH <10 mIU/L, age >70 years |
| TSH 4–10 mIU/L, age <65 years, symptoms (+) | TSH 4–10 mIU/L, age >65 years | |
| ETA (2013) [5] | TSH >10 mIU/L, age <70 years | TSH <10 mIU/L symptoms (–), age <70 years |
| TSH <10 mIU/L, age <70 years, symptoms (+) | TSH <10 mIU/L, age >70 years | |
| TSH <10 mIU/L, age >70 years, symptoms (+) or high cardiovascular (CV) risk | ||
| Clinical practice guideline (2017) [10] | TSH >10 mIU/L, age <70 years | TSH >10 mIU/L, age >70 years |
| Especially, symptoms (+) or CV risk factors | ||
| 6 months of LT4 treatment in the cases of TSH >4.5 and <7 mIU/L with symptoms or TSH >7 and <10 mIU/L, age <70 years symptoms (+) regardless of age, CV risk factors, TPOAb | ||
| NICE guideline (2018) [9] | TSH >10 mIU/L, age <70 years | TSH >10 mIU/L, age >70 years |
| TSH 4–10 mIU/L, age <65 years, symptoms (+) | TSH 4–10 mIU/L, age >65 years | |
| Clinical practice guideline (2019) [8] | Only women who are or trying to become pregnant or patients with TSH >20 mIU/L | Almost all adults |
| KTA (2023) [6] | TSH >10 mIU/L, age <70 years | TSH 6.8–10 mIU/L, age <70 years |
| All elderly patients | ||
LT4, levothyroxine; ATA, American Thyroid Association; TSH, thyroid-stimulating hormone; ETA, European Thyroid Association; TPOAb, thyroid peroxidase antibody; NICE, National Institute for Health and Care Excellence; KTA, Korean Thyroid Association.