Table 2.

Examples of subclinical hyperthyroidism scenarios and decision making considerations

Case Scenario	Decision Making Considerations
Case 1: A healthy 39-year-old woman has had TSH values between 0.3 and 0.4 mIU/L over the last year. Free T4 and Free T3 are normal. TRAb are negative and she has a normal 24-hour iodine uptake and scan. She is asymptomatic.	This is a young patient with a TSH slightly below the reference range (grade 1 subclinical hyperthyroidism) without an identified etiology. There is no evidence that treatment will be beneficial and observation is appropriate.
Case 2: A 75-year-old woman with a history of coronary artery disease, hypertension and hyperlipidemia is found to have a TSH of 0.05 mIU/L. Repeat TSH a month later is 0.08 mIU/L. Free T4 and Free T3 remain normal. She has palpable thyroid nodules and thyroid scintigraphy demonstrates toxic multinodular goiter.	This is an older, post-menopausal woman with known coronary artery disease. She has grade 2 subclinical hyperthyroidism. Given her age and risk factors, treatment is appropriate. Radioactive iodine is generally the preferred treatment, which would lead to hypothyroidism and the need for lifelong thyroid hormone replacement therapy. Anti-thyroid drugs can be used, but likely need to be continued indefinitely. Significant comorbidity (cardiovascular disease) weighs against the choice of surgery in this patient.
Case 3: A 59-year-old woman with osteopenia is found to have TSH values between 0.2 and 0.3 mIU/L over the last 6 months. Free T4 and Free T3 remain normal. TRAb is elevated.	This is a middle-aged woman with asymptomatic grade 1 subclinical hyperthyroidism. The etiology is likely Graves’ disease. Because she is post-menopausal and has low bone density, treatment should be considered though observation with close monitoring for progression is reasonable.