In addition to this post, please see Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement (2014)
Jonklaas, Bianco, et al., Thyroid 24(12): 1670-1751, 2014
In this post I link to and excerpt the Curbsiders’ section on “Subclinical Hypothyroidism: when to treat?” from #208 Hypothyroidism Master Class with Susan Mandel MD, MPH. APRIL 20, 2020 By DR ELENA GIBSON
Here are the excerpts:
Subclinical hypothyroidism (See more below)
Elevated TSH with a normal free T4. TSH should be repeated, at least a month apart (or sooner if pregnant). Treatment depends on age and TSH level.
Both the TSH and free T4 are lower than the normal reference range. Free T4 levels should be used for treatment management (Garber 2012).
Kashlak Pearl: Dr. Mandel tells patients to avoid biotin supplements for 2-3 days prior to thyroid testing to avoid falsely low TSH.
Subclinical Hypothyroidism: when to treat?
Subclinical hypothyroidism is defined as an elevated TSH with a normal free T4 (Cooper 2012). Depending on the studied population, treatment of subclinical hypothyroidism has been associated with prevention of adverse cardiovascular outcomes, improved hyperlipidemia and improvement in menstrual irregularities (Rodondi 2010, Cooper 2012).
TSH > 10, normal free T4
In all ages, this is significant subclinical hypothyroidism and one should consider treatment (Jonklaas 2014).
Age < 65 with subclinical hypothyroidism
Treating subclinical hypothyroidism in younger patients (<65 years old) with a TSH >7 is sometimes done because it has been associated with reduced adverse cardiovascular outcomes (Biondi 2019). For patients under the age of 65, some guidelines recommend treating if TSH is >7, and treatment should be considered if TSH >5 and symptoms are present (Cooper 2012). Any subclinical hypothyroidism in pregnancy should be treated (Cooper 2012, Biondi 2019).
Age >70 with subclinical hypothyroidism
It is important to consider how the normal TSH range shifts upwards with age, and a TSH of 6-7 in an elderly patient could be normal. Furthermore, treatment of subclinical hypothyroidism is not recommended in elderly patients unless the TSH is >10 because observational data has identified associations between higher TSH levels and improved mortality and well-being in elderly patients (Jonklaas 2014).