Thyroid Diseases
Conditions
Keywords
Levothyroxine, Liothyronine, Lipid Metabolism, Gluconeogensis, Thyrotropin Releasing Hormone, Deiodinase, Replacement Thyroid Hormone Therapy, Thyroidectomy, Near Total Thyroidectomy
Brief summary
This study will examine how two thyroid preparations-levothyroxine (T4) and liothyronine (T3)-affect fat and cholesterol metabolism, blood sugar regulation, and thyrotropin secretion in patients who have had their thyroid gland removed. Results of the study may help in the development of better therapies to optimize blood sugar and cholesterol levels in some patients. Patients 18 years of age or older who have had most or all of their thyroid gland removed and are taking long-term thyroid hormone medication may be eligible for this study after screening.
Detailed description
Thyroid hormone action plays an important role in the regulation of many physiologic processes, among them glucose and lipid metabolism. Interestingly, the clinical presentation of thyroid dysfunction is extremely variable, with relatively poor correlation between circulating hormone levels and clinical features. This finding suggests that the local, intracellular concentration of the active hormone liothyronine (T3), regulated by peripheral conversion of the pro-hormone levothyroxine (T4), is an important determinant in the maintenance of the thyroidal homeostasis. The aim of the present study is the evaluation of the role of peripheral thyroid hormone conversion in the regulation of glucose and lipid metabolism by assessing the differential response to T4 or T3 treatment in subjects devoid of endogenous thyroid hormone production. T3 administration bypasses peripheral metabolism and therefore will allow us to assess the role of the peripheral thyroid hormone conversion in the regulation of the hormone action at the end-organ level. Fifty hypothyroid subjects will be initially randomized to either of the thyroid hormone replacements liothyronine (T3) or levothyroxine (T4) treatment period (one arm cross-over design, with treatment sequence randomized), aimed to maintain serum TSH levels greater than or equal to 0.5 less than or equal to 1.5 mU/L, indicating full replacement. After a 30-day period of steady-state replacement the study subjects will be admitted to the Clinical Center and, after a three-day period of stabilization and an overnight fast, will undergo the following tests: escalating dose TRH stimulation test, indirect calorimetry, graded exercise tolerance test, DEXA scan, and echocardiogram. Patients will also undergo skeletal muscle biopsy and subcutaneous adipose tissue biopsy and microdialysis, as well as a two-step euglycemic hyperinsulinemic clamp with measurement of splanchnic gluconeogenesis. Fasting venous blood samples will be collected for the determination of the parameters of lipid, glucose and energy metabolism. After discharge, the patients will switch to the other form of thyroid hormone replacement therapy (second period) . The therapy will be adjusted in order to achieve the same therapeutic goal for TSH concentrations (greater than or equal to 0.5 less than or equal to 1.5 mU/L), analogous to that achieved during the first phase of the study (TSH less than or equal to 0.5 mU/L difference between T3 and T4 phases). After reaching a 30-day period of steady-state replacement, study subjects will be re-admitted to the Clinical Center and the previously described evaluation procedures will be repeated.
Interventions
DRUGLiothyronine and Levothyroxine
Hypothyroid patients are treated with Liothyronine and Levothyroxine in 2 crossover, randomized phases
Sponsors
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Masking
TRIPLE (Subject, Caregiver, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* INCLUSION CRITERIA: Age greater than or equal to 18 years, male or female. History of total or near total thyroidectomy or hypothyroidism on replacement therapy. For non-thyroidectomized patients, at least three-year history of replacement therapy (at least 1.2 mcg/Kg LT4/body weight), and less than 5% uptake at 24H on (123)I thyroid scan while on replacement therapy. Written informed consent.
Exclusion criteria
BMI less than or equal to 20 or greater than or equal to 30 kg/m(2). Metastatic thyroid cancer or history of thyroid cancer with high risk of recurrence requiring suppressive thyroid hormone therapy (Singer 1996). Significant thyroid residual greater than 1 mL as measured by ultrasound (limited to thyroidectomized patients) or greater than 5 percent uptake at 24H on (123)I thyroid scan while on replacement therapy (limited to hypothyroid patients not undergone total thyroidectomy). History or symptoms compatible with cardiovascular disease, including paroxysmal supraventricular tachycardia, atrial fibrillation, syncopal episodes or use of prescription medications for heart conditions, including antihypertensives. Allergy to lidocaine, isoproterenol, TRH, levothyroxine, liothyronine, Tylenol #3, oxycodone, nitroglycerin. Pregnancy or unwillingness to use non-hormonal contraception during the study. Breastfeeding Use of hormonal contraceptives or estrogen replacement therapy. Use of tobacco (smoking, chewing) for the two weeks preceding the hospital admissions (metabolic testing) Diabetes mellitus, either type I or II. Hypercholesterolemia (serum levels greater than or equal to 240 mg/dL), hypertriglyceridemia (plasma levels greater than or equal to 220 mg/dL) and/or use of antilipemic therapy. Liver disease or ALT serum level greater than two fold the upper laboratory reference limit. Renal insufficiency or estimated creatinine clearance less than or equal to 50 mL/min. Use of medications/supplements/alternative therapies known to alter thyroid function. Current history or symptoms compatible with psychosis including major depression (including history of hospitalization for depression, history of attempted suicide, history of suicidal ideation). Use of antipsychotic medications History of drug or alcohol abuse within the last 5 years; current use of drugs or alcohol (CAGE greater than 3). Keloid formation (relative to skeletal muscle and subcutaneous adipose tissue biopsies). Current or previous clinically significant (requiring medical/surgical intervention) extrathyroidal manifestations of autoimmune thyroid disease (dermopathy, ophthalmopathy, arthropathy).
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Insulin-mediated Glucose Disposal Rate at Levothyroxine Treatment Phase | One month of therapy. |
| Insulin-mediated Glucose Disposal Rate at Liothyronine Treatment Phase | One month of therapy |
Secondary
| Measure | Time frame |
|---|---|
| Triglycerides at Levothyroxine Treatment Phase | One month of therapy. |
| Triglycerides at Liothyronine Treatment Phase | One month of therapy. |
| Resting Energy Expenditure at Levothyroxine Treatment Phase | One month of therapy. |
| Resting Energy Expenditure at Liothyronine Treatment Phase | One month of therapy. |
| Left Ventricle Mass Index at Levothyroxine Treatment Phase | One month of therapy. |
| Total Cholesterol at Levothyroxine Treatment Phase | One month of therapy. |
| Apolipoprotein A-I at Levothyroxine Treatment Phase | One month of therapy. |
| Apolipoprotein A-I at Liothyronine Treatment Phase | One month of therapy. |
| Apolipoprotein B at Levothyroxine Treatment Phase | One month of therapy. |
| Apolipoprotein B at Liothyronine Treatment Phase | One month of therapy. |
| Left Ventricle Mass Index at Liothyronine Treatment Phase | One month of therapy. |
| Total Cholesterol at Liothyronine Treatment Phase | One month of therapy. |
Countries
United States
Participant flow
Recruitment details
Participants recruited from NIH Clinical Center, Bethesda, Maryland, USA between June 2005 and November 2007.
Pre-assignment details
110 participants inquired through phone; 24 screened, 10 excluded 8 did not meet inclusion criteria and 2 refused participation).
Participants by arm
| Arm | Count |
|---|---|
| Entire Study Population Includes groups randomized to receive Levothyroxine first and Liothyronine first. | 14 |
| Total | 14 |
Baseline characteristics
| Characteristic | Entire Study Population |
|---|---|
| Age, Continuous | 49.3 years STANDARD_DEVIATION 8 |
| Duration of hypothyroidism | 8.6 years STANDARD_DEVIATION 13.1 |
| Free thyroxine (T4) | 1.76 ng/dl STANDARD_DEVIATION 0.46 |
| Region of Enrollment United States | 14 participants |
| Sex: Female, Male Female | 13 Participants |
| Sex: Female, Male Male | 1 Participants |
| Thyroid stimulating hormone (TSH) | 1.1 mU/liter STANDARD_DEVIATION 1.4 |
| Triiodothyronine (T3) | 99.0 ng/dl STANDARD_DEVIATION 24.2 |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 1 / 14 | 0 / 14 |
| serious Total, serious adverse events | 0 / 14 | 0 / 14 |
Outcome results
Primary
Insulin-mediated Glucose Disposal Rate at Levothyroxine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Insulin-mediated Glucose Disposal Rate at Levothyroxine Treatment Phase | 7.26 mg/kg/min | Standard Deviation 2.7 |
Primary
Insulin-mediated Glucose Disposal Rate at Liothyronine Treatment Phase
Time frame: One month of therapy
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Insulin-mediated Glucose Disposal Rate at Liothyronine Treatment Phase | 7.37 mg/kg/min | Standard Deviation 4.4 |
Secondary
Apolipoprotein A-I at Levothyroxine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Apolipoprotein A-I at Levothyroxine Treatment Phase | 152 mg/dl | Standard Deviation 31 |
Secondary
Apolipoprotein A-I at Liothyronine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Apolipoprotein A-I at Liothyronine Treatment Phase | 144 mg/dl | Standard Deviation 16 |
Secondary
Apolipoprotein B at Levothyroxine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Apolipoprotein B at Levothyroxine Treatment Phase | 87 mg/dl | Standard Deviation 19 |
Secondary
Apolipoprotein B at Liothyronine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Apolipoprotein B at Liothyronine Treatment Phase | 72 mg/dl | Standard Deviation 15 |
Secondary
Left Ventricle Mass Index at Levothyroxine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Left Ventricle Mass Index at Levothyroxine Treatment Phase | 71 g/m^2 | Standard Deviation 16 |
Secondary
Left Ventricle Mass Index at Liothyronine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Left Ventricle Mass Index at Liothyronine Treatment Phase | 71 g/m^2 | Standard Deviation 19 |
Secondary
Resting Energy Expenditure at Levothyroxine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Resting Energy Expenditure at Levothyroxine Treatment Phase | 1201 kcal/24 hour | Standard Deviation 282 |
Secondary
Resting Energy Expenditure at Liothyronine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Resting Energy Expenditure at Liothyronine Treatment Phase | 1177 kcal/24 hour | Standard Deviation 323 |
Secondary
Total Cholesterol at Levothyroxine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Total Cholesterol at Levothyroxine Treatment Phase | 196 mg/dl | Standard Deviation 26 |
Secondary
Total Cholesterol at Liothyronine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Total Cholesterol at Liothyronine Treatment Phase | 174 mg/dl | Standard Deviation 28 |
Secondary
Triglycerides at Levothyroxine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Triglycerides at Levothyroxine Treatment Phase | 152 mg/dl | Standard Deviation 31 |
Secondary
Triglycerides at Liothyronine Treatment Phase
Time frame: One month of therapy.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Liothyronine/Levothyroxine Therapy Intervention Arm | Triglycerides at Liothyronine Treatment Phase | 144 mg/dl | Standard Deviation 16 |