Update on the treatment of hypothyroidism

Abstract

Purpose of Review Differentiated thyroid cancer is a malignancy that is rapidly increasing in frequency. As thyroidectomy plays a central role in the treatment of thyroid cancer, it is incumbent on physicians treating this patient group to be well versed in the intricacies of treating hypothyroidism. Recent findings Treatment of hypothyroidism may be refined by careful attention to dose selection, monitoring of therapy, and achievement of TSH goals that are specific to the individual patient’s overall clinical situation. These goals are common not only to patients with a sole diagnosis of hypothyroidism, as discussed in the recent American Thyroid Association Guidelines, but also to patients with hypothyroidism in the setting of thyroid cancer. Several recent studies have illuminated our understanding of the benefits and risks of TSH suppression therapy in patients with differentiated thyroid cancer. Multiple studies of combination therapy with levothyroxine and liothyronine for treating hypothyroidism have not lead to a clear conclusion about its benefits over levothyroxine monotherapy. Animal studies have advanced our understanding of the altered serum and tissue milieu that characterizes levothyroxine monotherapy. Crossing the bridge from this translational research into clinical research using sustained release triiodothyronine preparations may ultimately enhance the health of our patients. Summary Continued refinement of our understanding of thyroid status and our ability to flawlessly implement thyroid hormone replacement is an active area of research.

Hypothyroidism

“…[1][2][3] Annual TSH monitoring, with more frequent monitoring in special circumstances (e.g., pregnancy, major weight change or addition of potentially interacting medications), may facilitate appropriate dose adjustment. 3,4 If needed, the levothyroxine dose may be titrated with changes of about 12.5-25 µg, measuring TSH about four to eight weeks later.…”

“…[1][2][3] Annual TSH monitoring, with more frequent monitoring in special circumstances (e.g., pregnancy, major weight change or addition of potentially interacting medications), may facilitate appropriate dose adjustment. 3,4 If needed, the levothyroxine dose may be titrated with changes of about 12.5-25 µg, measuring TSH about four to eight weeks later. 1,4 Coingestion of levothyroxine with food may cause impaired absorption and should be avoided 1,3 Ideally, levothyroxine should be taken only with water at a consistent time, either one hour before breakfast or at bedtime more than three hours after the final meal of the day.…”

“…[1][2][3] In adults (other than in pregnancy), TSH values greater than 10 mIU/L or TSH elevations with low free thyroxine values are generally considered indications for levothyroxine treatment [1][2][3][4] (Appendix 1, available at www.cmaj.ca /lookup /suppl /doi:10.1503/cmaj .141596 /-/DC1). 5 age-specific target TSH levels have been recommended.…”

“…5 age-specific target TSH levels have been recommended. [1][2][3][4] Higher upper limits of TSH targets are acceptable for older people (e.g., up to 6 mIU/L in patients aged > 65 yr, with consideration of comorbidities).…”

“…In screening for primary hypothyroidism, only serum thyroid-stimulating hormone is required as a first-line test [1][2][3] In the general adult population (excluding pregnant women and older people), a normal thyroid-stimulating hormone (TSH) level is defined as the 95% laboratory-specific reference interval (about 0.45-4.50 mIU/L). [1][2][3] In adults (other than in pregnancy), TSH values greater than 10 mIU/L or TSH elevations with low free thyroxine values are generally considered indications for levothyroxine treatment [1][2][3][4] (Appendix 1, available at www.cmaj.ca /lookup /suppl /doi:10.1503/cmaj .141596 /-/DC1).…”