BACKGROUND
Thyroid hormone suppressive therapy means adjusting the levothyroxine dose after thyroidectomy to very low/undetectable levels. This is designed to prevent the growth of any remaining thyroid cancer cells after surgery, with or without radioactive iodine therapy. Early studies in advanced thyroid cancer showed clear benefits from this strategy if persistent cancer was present. However, there is no reason to pursue it in patients who do not have any evidence of persistent cancer. Therefore, the use of suppressive therapy should be guided by the risk of recurrence.

In the 2015 thyroid cancer guidelines, assigning risk of thyroid cancer recurrence (risk stratification) based on the assessment after the initial surgery drove initial TSH suppressive therapy decisions, as very specific TSH targets were recommended. This included complete suppression (TSH, <0.2 mU/L) in patients with an initial high-risk of recurrence, moderate suppression (TSH, 0.1–0.5 mU/L) in patients with an initial intermediate risk of recurrence, and a TSH in the lower half of the reference range for patients with a low initial risk of recurrence. How to evaluate the ongoing benefit versus risk of TSH suppressive therapy was not directly addressed previously, and at least five years of suppression was recommended.

However, treatment changes the risk of recurrence, with an excellent response to therapy having a different prognosis even in a patient with a high-risk cancer. In the 2025 guidelines, a focus on re-evaluating risk stratification allows for initial treatment response to play a role in the selection of TSH suppression therapy.

THE FULL ARTICLE TITLE
Ringel MD et al. 2025 American Thyroid Association management guidelines for adult patients with differentiated thyroid cancer. Thyroid 2025;35(8):841-985.

SUMMARY OF THE STUDY
The 2025 ATA thyroid cancer guidelines refer to patients with differentiated thyroid cancer, almost all of which are papillary thyroid carcinoma.

A major difference from the 2015 guidelines for the use of TSH suppression after surgery is that the 2025 recommendations base TSH goals on the continual re-evaluation of the patient’s response to therapy rather than on the risk evaluation based after initial therapy.

TSH suppressive therapy is now suggested only in those with evidence of possible persistent cancer, based on continued detectable thyroglobulin levels or possible abnormal thyroid tissue in the thyroid bed or abnormal lymph nodes. Ongoing reassessment of the patient’s response to therapy is recommended so that if no longer indicated (thyroglobulin levels become barely detectable/undetectable and concerning lymph nodes are no longer present), TSH suppression may be stopped. It is no longer recommended to continue TSH suppression for 5 years based on the initial surgical findings, because of the lower risk of recurrence if the postoperative assessment is consistent with an excellent response to therapy, regardless of the characteristics of the initial pathology.

The second major difference is that complete suppression (undetectable TSH) is no longer recommended. In fact, the current guidelines do not provide target TSH ranges for any patients, but simply state that TSH should be maintained “below” or “within” the reference range.

The support for these new guidelines are studies that show no benefit for levothyroxine treatment to a TSH less than 2 mU/L and 1 study that shows an increased risk of death from heart problems in thyroid cancer patients that is attributable to complete TSH suppression.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
The new guidelines provide more flexibility than the prior guidelines by shifting the “one size fits all” approach based on the initial treatment results. This allows clinicians to continually reassess the risk of thyroid cancer recurrence at every visit and to adjust levothyroxine therapy and TSH levels based on the response to therapy. As always, these decisions should result from a shared-decision making discussion with the patient and their doctor.

— Alan P. Farwell, MD

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