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Levothyroxine Suppressive Therapy in Thyroid Cancer
R Michael Tuttle, MD
Attending EndocrinologistAssistant Professor of Medicine
Memorial Sloan Kettering Cancer CenterSanford Weill Medical College of Cornell University
New York, NY
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Estimated New CasesUnited States, 2003
Breast
Prostate
Lung
Colon
Lymphoma
Leukemia
Kidney
Thyroid
Multiple Myeloma
Hodgkin
50 k 100k 150k 200k 250k
22,000 new cases1,400 deaths
American Cancer Society
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Standard Initial Treatment Usual Pathway
TotalThyroidectomy
Remove the thyroid with all cancerous tissue
Radioactive IodineTreatment
Destroy any microscopic residual
thyroid tissue
Completely dependent on exogenous levothyroxine
Without any functional thyroid
tissue
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Levothyroxine Therapy Thyroid Cancer
NormalizeTSH
Prevent Symptoms of Hypothyroidism
SuppressTSH
Decreased Risk of Recurrence of Thyroid
Cancer
Without any functional thyroid
tissue
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Levothyroxine Suppression
Free T4 Normal Range
(ng/dL)
TSH Normal Range
(mcU/mL)
0.8
2.0
0.4
4.4
<0.010.1
PrimaryHypothyroidism
ThyroidCancer
HyperthyroidSymptoms
IncreasedRecurrence
TSH Suppression
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Levothyroxine Suppression
Free T4 Normal Range
(ng/dL)
TSH Normal Range
(mcU/mL)
0.8
2.0
0.4
4.4
<0.010.1TSH
Suppression
12-15%increase
12-15%decrease
ThyroidCancer
HyperthyroidSymptoms
IncreasedRecurrence
ThyroidCancer
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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 28;156(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-Jun;7(3):202-20.
British Thyroid Association. Guidelines for the management of thyroid cancer. London: Royal College of Physician, 2002.