Levothyroxine Suppressive Therapy in Thyroid Cancer

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Levothyroxine Suppressive Therapy in Thyroid
Cancer

• R Michael Tuttle, MD
• Attending Endocrinologist
• Assistant Professor of Medicine
• Memorial Sloan Kettering Cancer Center
• Sanford Weill Medical College of Cornell
  University
• New York, NY

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Estimated New CasesUnited States, 2003
22,000 new cases 1,400 deaths
50 k 100k 150k 200k 250k
American Cancer Society
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Standard Initial Treatment Usual Pathway
Remove the thyroid with all cancerous tissue
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Levothyroxine Therapy Thyroid Cancer
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Levothyroxine Suppression
2.0
Free T4 Normal Range (ng/dL)
0.8
4.4
TSH Normal Range (mcU/mL)
0.4
TSH Suppression
0.1
lt0.01
6
Levothyroxine Suppression
2.0
Free T4 Normal Range (ng/dL)
0.8
12-15 increase
12-15 decrease
4.4
TSH Normal Range (mcU/mL)
0.4
TSH Suppression
0.1
lt0.01
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Levothyroxine Suppression Therapy

• Thyroid cancer
• Very narrow therapeutic window
• Small changes in administered dose
• Symptomatic hyperthyroidism
• Recurrence of disease
• Product substitution with alternatives that vary
  by more than 5-10 from the brand name product
  would be unacceptable in the treatment of
  thyroid cancer.

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Treatment GuidelinesThyroid Cancer

• Singer PA, Cooper DS, Daniels GH et al.
  Treatment guidelines for patients with thyroid
  nodules and well-differentiated thyroid cancer.
  American Thyroid Association. Arch Intern Med.
  1996 Oct 28156(19)2165-72.
• AACE/AAES medical/surgical guidelines for
  clinical practice management of thyroid
  carcinoma. American Association of Clinical
  Endocrinologists. American College of
  Endocrinology. Endocr Pract. 2001
  May-Jun7(3)202-20.
• British Thyroid Association. Guidelines for the
  management of thyroid cancer. London Royal
  College of Physician, 2002.