Table 1.

Examples of subclinical hypothyroidism scenarios and decision making considerations

Case Scenario	Decision Making Considerations
Case 1: A healthy 85-year-old man was screened for thyroid dysfunction. He is asymptomatic. Labs show TSH 6.1 mIU/L, normal free T4.	The TSH reference range shifts higher with aging and this result is within the age-adjusted reference range. Treatment is not recommended. Thyroid function tests should be repeated in 1-3 months.
Case 2: A 50-year-old woman with a history of type 1 diabetes underwent screening for thyroid dysfunction. Her TSH has increased from 4.5→7.5→10 mIU/L over the last year but free T4 remains normal. TPO Ab are positive. She feels well.	This patient most likely has underlying lymphocytic thyroiditis (Hashimoto’s thyroiditis). She has progressive subclinical hypothyroidism and has an increased risk of progressing to overt hypothyroidism due to the presence of TPO Ab. While data demonstrating that treatment reduces cardiovascular risk are lacking, treatment with levothyroxine should be strongly considered given her age, underlying disease and degree of TSH elevation.
Case 3: A 55-year-old woman with a history of hypertension, on lisinopril, was found to have a TSH of 7.5 mIU/L with repeat value of 7.8 mIU/L two months later. Free T4 is normal. She has worsening fatigue.	This is a relatively young individual with TSH values above the reference range, but below 10 mIU/L. She has symptoms that could relate to thyroid dysfunction, but are non-specific. While there is no evidence that treatment will improve her symptoms or cardiovascular risk, a trial of treatment is reasonable with reassessment of symptoms once TSH is normalized. An alternative approach is observation.