Metabolic Effects of Synthetic Thyroid Hormone for Thyroid Cancer Treatment

Background: \- Thyroid hormone is produced by the thyroid gland, an organ at the base of the neck. Thyroid hormone controls the body's metabolism and the function of many organs. The thyroid gland produces two forms of thyroid hormone: T4 and T3. People who have thyroid cancer are treated with thyroid hormone therapy (synthetic T4, levothyroxine), which at times needs to be stopped to allow for cancer treatments. At these times, a different form of thyroid hormone (synthetic T3, liothyronine) is used to reduce the symptoms caused by low levels of thyroid hormone. Researchers want to know more about how changes in T3 hormone affect the body and organ function. Objectives: \- To study how changes in T3 hormone levels affect the body and organ function. Eligibility: \- Individuals at least 18 years of age who have had most or all of their thyroid removed to treat thyroid cancer who need to stop taking their regular thyroid hormone dose in preparation for the treatment of thyroid cancer. Design: * The study involves a screening visit and a baseline evaluation. It also includes an 11-day inpatient hospital stay. * Participants will be screened with a physical exam and medical history. They will also have blood tests and a neck ultrasound. * Participants will be evaluated with a physical exam, blood tests, and the following procedures: * Glucose tolerance test to measure blood sugar * Tests of body fat, muscle strength, and calorie burning levels * Imaging studies of the heart, liver, and thigh muscles * Quality of life questionnaires * Food preference and diet questionnaires * After 4 weeks of treatment with T3 hormone, participants will have an 11-day inpatient hospital stay to study the effect of thyroid hormone on their metabolism. The stay will involve the same tests done in the baseline evaluation.

Sex

All

Minimum age

18 Years

Maximum age

99 Years

* INCLUSION CRITERIA:

Subjects will be adult volunteers older than age 18 who underwent total thyroidectomy for the treatment of differentiated thyroid cancer, previously undergone radioactive iodine ablation of the thyroid gland remnant, with clinical indication for withdrawal from thyroid hormone replacement therapy in preparation for nuclear medicine imaging or therapeutic procedures with radioactive iodine. The patient population will be recruited from the participants in the 77-DK-0096 natural history protocol: Studies on Thyroid Nodules and Thyroid Cancer , PI Dr.Joanna Klubo-Gwiezdzinska and from the 10-C-0102 natural history protocol: Clinical and Genetic Studies in Familial Non-Medullary Thyroid Cancer , PI Electron Kebebew.

EXCLUSION CRITERIA:

1. Significant thyroid residual greater than 5 gm as measure by ultrasound or greater than 5 percent uptake at 24 H on (123) I pre-treatment thyroid scan.
2. Renal insufficiency or estimated creatinine clearance less than or equal to 60 mL/min/1.73M(2) BSA by MDRD equation before thyroid hormone withdrawal.
3. Liver disease or ALT \>2.5 times the upper laboratory reference limit.
4. Pharmacologic therapy for the treatment of psychiatric conditions.
5. History of, and/or current coronary artery disease.
6. Current history or symptoms compatible with psychosis or major depression (including history of hospitalization for depression, history of attempted suicide, history of suicidal ideation). Use of antipsychotic medications.
7. History of drug or alcohol abuse within the last year; current use of illicit drugs or alcohol abuse (CAGE\>3).
8. Pregnancy (women of child-bearing potential must have a negative pregnancy test prior to inclusion) or use of hormonal contraceptives.
9. Known allergy to L-T3.
10. Current use of prescription medication or certain non-prescription medications and dietary supplements known to affect thyroid function and/or metabolism, or alter the pharmacokinetics of L-T3.
11. Inability or unwillingness to follow the low-iodine, metabolic diet or non-compliance to the L-T3 administration regimen.
12. The presence of persistent diarrhea or malabsorption syndromes that would interfere with the patient s ability to adequately absorb drugs.
13. Inability to obtain venous access for sample collection, or basal hemoglobin of less than or equal to 10 g/dL.
14. Low functional status (ECOG Performance Status \> 2)

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