Clinical trial NCT03098433
Conditions: Healthy
Sponsor: Virginia Commonwealth University
Start date: 2017-10-20; Completion date: 2019-06-24
Enrollment: 22 participants; Allocation: RANDOMIZED; Intervention model: CROSSOVER

Brief summary:
This study will assess the short term effects of a single dose of liothyronine on the cardiovascular system and energy expenditure

Detailed description:

Arms: arm 1: Each participant will receive a single dose of lithyronine arm 2: Each participant will receive a single dose of levothyroxine arm 3: Each participant will receive a single dose of placebo
Interventions: intervention 1: Liothyronine intervention 2: Levothyroxine intervention 3: Placebos
Intervention descriptions: intervention 1: Single dose intervention 2: Active comparator intervention 3: Placebo

Protocol documents:
ICF_000.pdf: 
 
 
Title: Effects of Liothyronine on Energy Expenditure and Cardiovascular Function 
 
NCT #: NCT03098433 
 
Document approval date: September 25, 2019 
 
Document Type: Informed Consent 
 
 
 


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RESEARCH PARTICIPANT INFORMATION AND CONSENT FORM
TITLE:  In vivo characterization of the non-genomic effects of T3 on endothelial and    
cardiovascular function
VCU IRB PROTOCOL NUMBER: HM20005777
PRINCIPAL INVESTIGATOR: Francesco Celi, MD, MHSc.
SPONSOR: Virginia Commonwealth University 
Please ask the study doctor or the study staff to explain any information in this consent 
document that is not clear to you. You may take home an unsigned copy of this consent form 
to think about or discuss with family or friends before making your decision.
VOLUNTARY PARTICIPATION AND WITHDRAWAL
Your participation in this study is voluntary.  You may decide to not participate in this study.  
Your decision not to take part will involve no penalty or loss of benefits to which you are 
otherwise entitled.  If you do participate, you may freely withdraw from the study at any time.  
Your decision to with draw will involve no penalty or loss of benefits to which you are 
otherwise
PURPOSE OF THE STUDY
The purpose of this research study is to compare two different drugs used for hypothyroidism, 
a disease in which the thyroid is unable to produce enough hormones to regulate some of the 
body functions. This study may help guide the future development of medicines used in 
hypothyroidism. You are being asked to participate in this study because you may meet the 
requirements for study participation.
DESCRIPTION OF THE STUDY 
Hypothyroidism is a common condition that occurs when the thyroid does not produce 
enough hormones to regulate body functions. Patients with hypothyroidism are usually given 
tablets that contain replacement thyroid hormones: LT4 or LT3. Levothyroxine (LT4) is an 
inactive form of the thyroid hormone that must be converted into its active form (T3) in the 
body. Several studies showed that LT4 might not be sufficient to produce enough T3 in the 
body. For this reason, the addition of a synthetic form of T3, called liothyronine (LT3), is 
thought to improve the symptoms of hypothyroidism. 
The U. S. Food and Drug Administration (FDA) has approved both drugs, LT4 and LT3, in tablet 
form for the treatment of hypothyroidism. However, in this study, these drugs will be given in 
liquid form. This study is designed to compare LT4 and LT3 to each other and to placebo (a 
look-alike inactive substance). The study will test whether LT3 works differently than LT4 on 
the cardiovascular system and help us to better understand the effects of these drugs on your 
heart and on the metabolism of your body.
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Thyroid hormone medications (levothyroxine and liothyronine) are used to treat lo thyroid 
hormone levels, which are caused by surgery or disease of the thyroid gland. In this study, we 
use thyroid hormone medications to study their effects on the heart and the vascular system. 
This is defined as “experimental” use of a drug, where there is no immediate expectation to 
cure or treat a disease. Although the levothyroxine and liothyronine have been used for many 
years, there is always the possibility that you may develop an unexpected reaction.
Your participation in this study will include one screening visit (to make sure that you qualify 
for the study) plus three additional visits. During the three visits, we will measure the effects of 
the drugs on the heart and the metabolism. Approximately 20 individuals will participate in 
this study. 
The screening visit will last approximately 45 minutes, and it can be scheduled in either the 
morning or afternoon. Each of the study visits will last approximately 5 hours and a half and 
will be scheduled in the morning. 
PROCEDURES
If you decide to be in this research study, you will be asked to sign this consent form after you 
have had all your questions answered. 
At your screening visit (Visit 0), your medical, social and medication history will be recorded 
and a physical exam will be performed. This exam will include measurements of your weight 
and vital signs (pulse, blood pressure and temperature). Blood samples will be collected for 
routine lab tests and to determine eligibility. Approximately 1 to 2 tablespoons of blood will be 
collected. If you are unsure of your pregnancy status, a blood pregnancy test will be 
performed. If the result of the test is positive, the medical responsible investigator will notify 
you and you will not qualify to participate in the study. You will also have an electrocardiogram 
(EKG - tracing of the electrical activity of the heart) performed. 
If you qualify for the study, you will be scheduled for visits 1, 2 and 3. During Visits 1, 2 and 3, 
you will be randomly assigned (like a flip of a coin) to receive LT3, LT4, or placebo. By the end 
of the study, you will have received all three treatments (one per visit).
Your first visit (Visit 1) will be scheduled at least 24 hours after your screening visit. Prior to 
Visit 1, you will need to be fasting for at least 8 hours. An abbreviated history and physical 
examination with recording of height, weight, waist and hip measurements and vital signs 
(temperature, pulse, respirations and blood pressure) will be performed. A cannula (small 
plastic tube) will be inserted in the arm to draw blood. EKG electrodes will be placed on your 
chest/shoulder/leg and a finger-cuff will be placed to record blood pressure and cardiac 
function. A cardiac ultrasound (echocardiography) will also be done to measure heart function. 
We will also use a Bio-Impedance Analysis (BIA) as a mean to measure body composition. 
Specifically, BIA measures the amount of fluid (water) in your body. You will be asked to lie flat 
on a bed while four electrodes (two on the foot and two on the hand) are applied. A very low-
intensity electrical current (so low that you cannot feel it) is run through your body to measure 
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the amount of fluid (water) in your body. The test will last approximately 5 to 10 minutes. 
After these measurements, you will be asked to enter in a room and rest in a chair during the 
rest of the visit. This room is  called an indirect calorimeter chamber and will measure how 
much energy you are consuming. Once in the room, you will be asked to rest for 30 minutes 
before one of the study drugs (or placebo) will be administered in liquid form. The study drug 
administered will be randomly chosen (like the flip of a coin) between LT3, LT4 and placebo. 
Additional blood will be drawn every 60 minutes (for a total of 4 hours) after the study drug 
has been administered. Once finished, the canula will be removed from your arm, vital signs 
(Temperature, pulse and blood pressure) will be obtained, you will be asked to leave the room 
and an additional ultrasound of your heart will be performed.
Visit 2 and visit 3 will repeat the exact same procedures performed in visit 1. However, the 
treatment administered will change each time to assure, so that by the end of the study you 
will have received all three treatments (LT3, LT4, and placebo).
Neither you nor the study doctor will know which study drug you are receiving. This is done 
(blinding) so that a fair evaluation of results may be made. This information is only available to 
the study doctor if needed in an emergency.
ALTERNATIVE TREATMENTS OR PROCEDURES 
This is not a treatment study.  The procedures performed are for study related purposes only 
and not intended to diagnose or treat any specific disease.  However, some of the procedures 
performed in this study are also available in the health care environment.  Please talk with 
regular doctor to see if they are ones you need or want.  The following test performed for the 
study that are also available as a part of medical care include routine laboratory test 
(chemistry and Hematology, pregnancy test), Electrocardiogram -EKG (EKG - tracing of the 
electrical activity of the heart), and Echocardiogram ECHO used to measure heart function. 
Visit #
0 (Screening)
1
2
3
Physical assessment
X
X
X
X
Baseline blood draw
X
X
X
X
Echocardiogram
X
X
X
Electrocardiogram
X
X
X
X
Finger cuff blood pressure 
measurement
X
X
X
Bio-electrical Impedance Analysis
X
X
X
Metabolic chamber measurement
X
X
X
Blood draw while in the metabolic 
chamber 
X
X
X
LT3 or LT4 or Placebo administration
X
X
X
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RISKS AND DISCOMFORTS
LT3 or LT4 are generally well tolerated but, although unlikely, some side effects are possible:

Tachycardia (rapid heart rate) (up to 2% in chronic use)

Skipped heart beats (up to 6% in chronic use)

Myocardial infarction (up to 2% in chronic use) 

Low blood pressure (up to 2% in chronic use)

Sudden death (up to 2% in chronic use)

Anxiety

Heat intolerance

Weight loss
Note that you will receive a single dose of each of the study drugs, and that the percentages 
we are reporting refers to patients who generally have concomitant illnesses and are treated 
every day with these drugs.
Allergic reactions to LT4 and LT3 are possible.  Severe allergic reactions can be life threatening.
The effects of LT3 and LT4 in pregnant women might involve a risk to the embryo or fetus. 
Therefore, pregnant women may not participate in this study. For similar reasons, women who 
are nursing an infant may not participate in this study. Women who might become pregnant 
should use a medically accepted form of birth control.  
Other risks to participation in this study include the following:

Pain or bruising during blood draws. In rare cases, blood draws may results in 
skin/tissue infection. When possible, blood will be drawn from an existing intravenous 
cannula (tube) or at the same time as regular (standard) clinical blood draws to 
minimize the use of extra blood draws.

The placement of intravenous needles may cause transient pain, and occasional 
infection or bruising at the insertion site.

Minor discomfort of your arm or finger during blood pressure measurement.

Minor discomfort associated with the placement and removal of the electrodes on your 
skin.
BENEFITS TO YOU AND OTHERS
There is no guarantee or expectation that you will receive any medical benefits from being in 
this study. However, this study will significantly improve the knowledge of the two tested drug 
to treat hypothyroidism. In addition, information from this research study may lead to a better 
treatment in the future for people with hypothyroidism.
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USE AND DISCLOSURE OF PROTECTED HEALTH INFORMATION
Authority to Request Protected Health Information
The following people and/or groups may request my Protected Health Information:

Principal Investigator and Research Staff    

Study Sponsor    

Research Collaborators    

Institutional Review Boards   

Data Safety Monitoring Boards   

Government/Health Agencies  

Others as Required by Law
Authority to Release Protected Health Information 
The VCU Health System (VCUHS) may release the information identified in this authorization 
from my medical records and provide this information to:  

Health Care Providers at the VCUHS   

Principal Investigator and Research Staff     

Study Sponsor  

Research Collaborators     

Data Coordinators  

Institutional Review Boards     

Data Safety Monitoring Boards     

Government/Health Agencies     

Others as Required by Law
Once your health information has been disclosed to anyone outside of this study, the 
information may no longer be protected under this authorization.
Type of Information that may be Released 
The following types of information may be used for the conduct of this research:
 Complete health record
 Diagnosis & treatment codes
 Discharge summary
 History and physical exam
 Consultation reports
 Progress notes
 Laboratory test results
 X-ray reports
 X-ray films / images
 Photographs, videotapes
Complete billing record
 Itemized bill
 Information about drug or alcohol abuse
 Information about Hepatitis B or C tests
 Information about psychiatric care
 Information about sexually transmitted diseases
Expiration of This Authorization  
 This authorization will expire when the research study is closed, or there is no need to 
review, analyze and consider the data generated by the research project, whichever is 
later.
 This research study involves the use of a Data or Tissue Repository (bank) and will never 
expire.
  Other (specify):       
Right to Revoke Authorization and Re-disclosure
You may change your mind and revoke (take back) the right to use your protected health 
information at any time.  Even if you revoke this Authorization, the researchers may still use or 
disclose health information they have already collected about you for this study. If you revoke 
this Authorization, you may no longer be allowed to participate in the research study. To 
revoke this Authorization, you must write to the Principal Investigator.
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COSTS
The sponsor will provide the study drug.  There are no charges for the any of the procedures 
conducted during the study visits. 
PAYMENT FOR PARTICIPATION 
You will be paid $25 at completion of screening visit (Visit 0), $35 for each completed visit (1, 2 
and 3) and $70 as bonus if you complete all scheduled study visits. The maximum total 
payment is $200. If you withdraw from the study before completion, you will be paid 
depending on the number of visit you completed. 
VCU is required by federal law to collect your social security number. Your social security 
number will be kept confidential and will only be used to process payment.
CONFIDENTIALITY 
Potentially identifiable information about you will consist of blood samples and data 
abstracted from the medical record.
It will be noted in your protected electronic medical record at VCU Health System that you are 
in this clinical trial. Information about the study including any medications you may receive will 
be noted in the record. This information is protected just as any of your other medical records 
are protected. 
Your data will be identified by ID numbers, not names, and stored separately from medical 
records in a locked research area. All personal identifying information will be kept in password-
protected files. Access to research data will be limited to study personnel. A data and safety 
monitoring plan is established.
A description of this clinical trial will be available on http://www.ClinicalTrials.gov, as required 
by U.S. Law. This Web site will not include information that can identify you. At most, the 
website will include a summary of the results. You can search this Web site at anytime.
Although results of this research may be presented at meetings or in publications, identifiable 
personal information pertaining to participants will not be disclosed.  
In general, we will not give you any individual results from the study. If the study finds any 
clinically relevant or new findings during the course of the research, the study doctor will 
notify you. If we find something of medical importance to you we will inform you and your 
primary care physician with your permission, although we expect that this will be a very rare 
occurrence.
There are no plans to share any money or profits with you if the use of your sample(s) results   
in inventions or discoveries that have commercial value.  
The information and samples collected as part of this study will not be used or distributed for 
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future research studies, even if identifiers are removed. 
GENETIC TESTING
This study will use your samples to sequence all or part of your DNA.  Deoxyribonucleic acid 
(DNA) is the “blueprint” or “recipe” that gives the body’s cells instructions on how to do their
 jobs. Scientists can use a test called whole genome sequencing to determine the order of all 
or part of the molecules that make up your DNA, like reading all the letters in a  book 
sequencing is usually done to look for changes in the molecules of DNA that may cause health 
problems..  In this study, genetic testing will be performed by using part of the collected blood 
during Study visit 1 only. We will study variants in the genes that regulate the response to the 
thyroid hormone, and genes that regulate the metabolism of thyroid hormone medications to 
see if any of these changes is associated to a different response to the study medications. 
These changes are not associated with diseases, and have no clinical importance. We are not 
planning to screen for genetic diseases, and the information collected are devoid of clinical 
interest. As such, you will not be informed of the findings of this analysis. We do not expect to 
develop any commercial product from this study, but please note that the data generated by 
the use of genetic material in this study are property of the Virginia Commonwealth University. 
You can decide to decline to participate in the genetic testing but still being part of the non-
genetic study.  If you decide that you do not want to participate in the DNA part of the study 
blood for this test will not be collected.
1. My blood samples may be stored and used for future research about genetic testing 
  YES
  NO
initial
initial
 COMPENSATION FOR INJURY or ILLNESS 
If you are injured by, or become ill, from participating in this study, please contact your study 
doctor immediately.  Medical treatment is available at the Virginia Commonwealth University 
Health System (VCU Health System). Your study doctor will arrange for short-term emergency 
care at the VCU Health System or for a referral if it is needed.  
Fees for such treatment may be billed to you or to appropriate third party insurance.  Your 
health insurance company may or may not pay for treatment of injuries or illness as a result of 
your participation in this study.  
To help avoid research-related injury or illness it is very important to follow all study 
directions.
PARTICIPATION WITHDRAWAL
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Your participation in this study may be stopped at any time by the study doctor or the sponsor 
without your consent. The reasons might include:

the study doctor thinks it necessary for your health or safety;

you have not followed study instructions;

the sponsor has stopped the study; or

administrative reasons require your withdrawal. 
QUESTIONS
If you have any questions, complaints, or concerns about your participation in this research, 
contact:
Celi, Francesco, MD, MHSc.
Virginia Commonwealth University
Sanger Hall 7th Floor – Room 7-007
Richmond, VA, 23298
Phone: (804) 828-9696, (804) 628-1631 
Fax: (804) 828-8389
The researcher/study staff named above is the best person(s) to call for questions about your 
participation in this study. If you have general questions about your rights as a participant in 
this or any other research, you may contact:
Office of Research
Virginia Commonwealth University
800 East Leigh Street, Suite 3000
P.O. Box 980568
Richmond, VA 23298
Telephone: (804) 827-2157
Contact this number to ask general questions, to obtain information or offer input, and to 
express concerns or complaints about research. You may also call this number if you cannot 
reach the research team or if you wish to talk to someone else. General information about 
participation in research studies can also be found at http://www.research.vcu.edu/irb/ 
volunteers.htm.
Do not sign this consent form unless you have had a chance to ask questions and have 
received satisfactory answers to all of your questions.  CONSENT 
I have been provided with an opportunity to read this consent form carefully.  All of the 
questions that I wish to raise concerning this study have been answered.  
By signing this consent form, I have not waived any of the legal rights or benefits, to which I 
otherwise would be entitled.  My signature indicates that I freely consent to participate in this 
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research study and to contact me in case of abnormalities.  I will receive a copy of the consent 
form once I have agreed to participate.
I give my permission to contact my primary care physician if abnormal results are found.
 YES       
 NO        
________________________________________________
Participant Name, printed
________________________________________________          ________________
Participant Signature 
       Date
______________________________________________
Name of Person Conducting Informed Consent / Witness
(Printed)
________________________________________________          ________________
Signature of Person Conducting Informed Consent / Witness
       Date
________________________________________________          ________________
Principal Investigator Signature (if different from above) 
        Date 
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Prot_SAP_002.pdf: 
 
 
Title: In vivo characterization of the non-genomic effects of T3 on endothelial and cardiovascular function 
 
NCT #: NCT03098433 
 
Document date: 01/19/2017 
 
Document Type: Protocol and Statistical Analysis Plan 
 
 
 


In vivo characterization of the non-genomic effects of T3 on endothelial and cardiovascular function 
 
Study protocol 
Research Description 
Hypothyroidism is a common condition caused by failure of the thyroid gland or as a result of thyroid 
surgery for benign or malignant lesions. Hypothyroidism is treated by administering levothyroxine (LT4) 
a synthetic inactive form of the thyroid hormone. This drug is then metabolized by the organism into its 
active form, T3.  
Several lines of evidence indicate that LT4 alone may not be sufficient in assuring adequate tissue levels 
of T3 and some studies suggest that the addition of liothyronine (LT3) the synthetic form of T3 to LT4 
can improve the symptoms and signs associated with hypothyroidism. LT3 has a short half life and it is 
usually administered in two-three doses daily. There is also evidence supporting the hypothesis that T3 
exerts rapid, “non genomic” effects, particularly on the vessels. If this is the case a tight regulation of the 
LT3 dose to maintain the serum concentration of T3 becomes of primary importance. 
To assess the non genomic effect of LT3 we will perform a proof-of-concept, double blind randomized 
crossover study in twenty healthy volunteers aimed to measure the acute cardiovascular and energy 
expenditure changes following a single equimolar dose of LT3 or LT4.  
Specific aims or goals. 
Aim 1: To compare the effects of a single dose of 0.7mcg/kg in liquid formulation (equivalent to a dose 
of 50 mcg in a 70 Kg individual) of LT3 to an equimolar 0.86 mcg/kg single dose of LT4 in liquid 
formulation, and to placebo on cardiovascular system. We will record the following parameters: heart 
rate, blood pressure, cardiac output, flow-mediated dilation. 
Aim 2: To compare the effects of a single dose of 0.7mcg/kg of LT3 in liquid formulation to an 
equimolar single dose of LT4 in liquid formulation, and to placebo on the energy metabolism and 
substrate utilization. We will record the following parameters: energy expenditure by whole room 
indirect calorimeter, respiratory quotient, skin and core temperature. 
Aim 3: To measure the changes in circulating thyroid hormone following a single dose of 0.7mcg/kg of 
LT3 in liquid formulation to an equimolar single dose of LT4 in liquid formulation, and to placebo. We 
will record at multiple time points the following parameters: free T3, free T4, TSH. 
Background and significance. 
Thyroid hormone (TH) affects development, growth and function on the majority of tissues of the 
organism and the specificity of the signaling is assured by a complex, multilevel system that assures 
time- and tissue-specificity of the hormonal signal relatively independent from the circulating levels(1). 
Among the various systems, the peripheral metabolism of pro-hormone T4, the main product of the 
thyroid, into the hormonally active T3 plays a crucial role in assuring the tissue-specific delivery of the 
hormonal signal(2). Two enzymes, type-1 (D1) and type-2 (D2) deiodinase, convert T4 into T3.  Of note, 
D1 is thought to be responsible for a substantial fraction of circulating T3(3). Hypothyroidism is an 
extremely prevalent condition affecting approximately up to 10% of the adult population and is 


associated with dyslipidemia, cognitive impairment, hypertension, and increased cardio-vascular 
morbidity and mortality(4, 5). Autoimmune thyroid disease (AITD) is the most common etiology of 
hypothyroidism in the US and it is characterized over a period of years by progressive loss of functional 
parenchyma. Since the thyrotroph is exquisitely sensitive to minimal changes in circulating TH, a 
compensatory increase in Thyroid Stimulating Hormone (TSH) secretion occurs while levels of TH are still 
well within the range of normality. This is illustrated by the classical linear-logarithmic relationship 
between free T4 and TSH(6). As the disease progresses, while the circulating T4 decrease to frankly 
pathologic levels, T3 tends to remain within normal range until extreme hypothyroidism ensues(7, 8). 
Similar conditions are observed in iodine insufficiency, and in experimental models of perturbation of 
the thyroid homeostasis(9). In aggregate, these observations suggest that multiple homeostatic 
mechanisms have developed to protect the circulating, and by extension the intracellular levels, of T3. 
Of interest, some of the hormonal actions of T3 are exerted via a rapid non-genomic pathway, which 
appears to play an important role in some of the cardiovascular effects of TH(10, 11). The therapy of 
hypothyroidism consists in administration of LT4, which in turn is converted into the active metabolite 
T3 in the peripheral tissues by D1 and D2. The therapeutic goal is a TSH within normal range, indicating 
the achievement of euthyroidism at the level of the thyrotroph on the assumption that a state of 
pituitary euthyroidism equates to adequate T3 concentration in all the tissue targets of the hormonal 
action(12). This assumption has been challenged by clinical observations(13), clinical trials(14), and 
mechanistic studies(15). The results of clinical studies aimed to measure the effects of TH replacement 
on “hard” endpoints (i.e. mortality and cardiovascular events) have been marginal or disappointing, 
particularly in subclinical hypothyroidism and in the elderly(16). This is surprising since the cross-
sectional data provide compelling evidence of the association between hypothyroidism and indexes of 
cardiovascular risk. Collectively these data question the utility of TH replacement, its therapeutic goals, 
the target population who could benefit from the intervention, and the modality of the treatment, and 
indeed there is active discussion on this very topic within the thyroidologist community(17). The 
attempt to provide a more “physiologic” form of therapy has led to the experimentation of 
combinationLT3 /LT4 regimens(13, 18-29), or to the use of thyroid extracts(30). Furthermore, some 
observations suggest that carriers of a common polymorphism of the D2 gene (Thr92Ala) (31)may 
benefit from combination therapy, suggesting a pharmacogenomics component in the therapeutic 
response(14, 32). This information indicate that the current therapy for hypothyroidism is costly and 
suboptimal, and there is need for a formal characterization of the pathophysiologic state of 
hypothyroidism during replacement treatment. 
This project challenges the established notion that LT4 generates identical biological effects on the 
pituitary and on the end-organ tissues, and pituitary euthyroidism (i.e. a normal TSH) is 
pharmacodynamically equivalent to production of TH from the normal thyroid gland. We will interrogate 
the clinical relevance of non-genomic effects of TH by assessing the short-term effects of a single-dose 
of LT3 on endothelial and cardiovascular function. This translational project will provide important 
information on the need (or lack thereof) of maintaining stable circulating levels of T3. In this clinical 
protocol, we chose as primary endpoints measurable and clinically relevant indices of TH action, which 
in turn could be used in the future as outcomes for large intervention studies. Specifically, beside 
measurements of circulating TH, we will assess energy expenditure(33, 34) and endothelial (35, 36)and 
cardiovascular function(37). The results of the proposed experiments will shed light on the interaction 
between the pathophysiologic state of hypothyroidism and administration of therapy, providing new 


insights on the clinical rationale and utility of targeting the circulating levels of T3. Collectively, these 
studies will expand the knowledge base necessary to design a rationale treatment of hypothyroidism. 
Study design. 
Proof-of-concept, randomized double blind cross-over study in healthy volunteers. Twenty adult healthy 
volunteers will be invited to participate in the study.  
A) Screening visit. Age >18<45 year, BMI >20<30 kg/m2 TSH >0.5<5.0 mcIU/mL and no evidence of 
thyroid autoimmunity by history or anti-thyroid peroxidase (TPO) antibodies measurement. Exclusion 
criteria will be: pregnancy; hypothyroidism or autoimmune thyroid disease by history or presence of anti 
TPO antibodies; use of prescription drugs; diabetes mellitus; dyslipidemia; coronary artery disease; 
hypertension (systolic blood pressure > 140 mm/Hg, and/or diastolic blood pressure > 90 mm/Hg); 
anemia; renal insufficiency; liver disease or ALT >2.5 x the upper laboratory reference limit; psychiatric 
conditions; and current tobacco use. During the screening visit, the following procedures will be 
performed: informed consent, history and physical examination, EKG, CBC, glucose, creatinine, ALT, hCG 
(in females), TSH, freeT4, TPO, and genomic DNA.  
B) Study visit #1-3. Study participants will be evaluated in the morning after an overnight fast during 
three consecutive outpatient visits, with at least a 24-hour interval between. Upon arrival to the Clinical 
Research Service Unit (CRSU) and abbreviated history and physical examination with recording of 
anthropometrics will be obtained; an i.v. cannula will be inserted in the left arm. Study volunteers will 
be fitted with electrodes for EKG Holter recording, and a cuff on the third finger of the right hand to 
record blood pressure and heart rate, cardiac output, systemic vascular resistance and endothelial 
function.  An echocardiogram will be recorded at the beginning and at the end of each study session. 
Study volunteers will then enter in the whole room (“Flex room”) a 4’ x 8’ x 7’ indirect calorimeter with a 
temperature set at 24°C and rest on a bed. The Flex room has a window and a TV monitor, and is 
connected to the nursing station via an interphone system. An i.v. port is located on the door of the Flex 
room allowing drawing of samples without compromising the recording of energy expenditure. After 40 
minutes (time 0’), study volunteers will receive either 0.7mcg/kg (equivalent to a dose of 50 mcg in a 70 
Kg individual) of LT3 to an equimolar 0.86 mcg/kg single dose of LT4, and to placebo in liquid form. The 
doses were chosen to be within the usual therapeutic range prescribed in preparation for radioiodine 
ablation. Blood samples will be obtained at the following time points: 0’, 60’ 120’ 180’ 240’ for total and 
free T3, total and free T4, TSH and 500 l aliquots of serum TSH will be recorded at times 0’ and 240’ of 
each Study visit. Energy expenditure and respiratory quotient will be recorded throughout the duration 
of the stay in the Flex room. The first 20 minute of the recording will be discarded to allow for 
equilibration. At the end of the session the i.v. cannula will be removed, vital signs recorded and the 
volunteer will be discharged provided with a coupon for a meal in the hospital cafeteria. The same 
procedures will be repeated in the identical order and timing for the other formulations. 
Justification for the sample size: 
The primary analysis will be performed by two-tailed paired t-test with an 0.05  error as a threshold for 
statistical significance on the assumption that LT3 administration, compared to LT4 will result in a 30% 
increase in FMD, corresponding to 0.75 SD. Using this experimental conditions and assumptions, a 20 
volunteers will provide 88% power to detect a significant difference, while assuming a 20% drop-out 
rate the power will be 80%. 


List the study inclusion criteria: 
Healthy  volunteers, both sexes 
Age range 18-45 year 
Body Mass Index range 20- 30 kg/m2  
Ability to provide informed consent to the participation in the study 
List the study inclusion criteria: 
Abnormal TSH (>0.5<5.0 mcIU/mL) 
Thyroid disease or autoimmunity by history or anti-thyroid peroxidase (TPO) antibodies.  
Pregnancy or lactation 
Chronic use of prescription drugs 
Diabetes mellitus (by history or fasting glucose >126 mg/dl) 
Dyslipidemia (total cholesterol >240 mg/dl) 
Hypertension ( by history or screening systolic blood pressure > 140 mm/Hg, and/or diastolic blood 
pressure > 90 mm/Hg) 
Cardiac arrhythmia (by history or screening EKG) 
Anemia (Hb<13.3 g/dl M, 12.0 g/dl F)  
Renal insufficiency by history or estimated creatinine clearance ≤ 60 mL/min/1.73m2 BSA. 
Liver disease or transaminases >2.5 x the upper laboratory reference limit.  
Current tobacco use. 
Criteria for withdrawing an individual participant from the study: 
Volunteers may withdraw from the study at any time. The investigators can withdraw any volunteer at 
any time from the study if medically necessary.  
Medical reasons for withdraw from the study: 
1) Tachycardia (heart rate greater than 100/min) 
2) Anxiety 
3) Development of hypertension (systolic >160 mmHg, diastolic > 90 mmHg) following 
administration of the study drug 
4) Development of hypotension (systolic <90 mmHg, diastolic < 60 mmHg) following administration 
of the study drug 
Adverse events mitigation: 
All AEs and SAEs will be followed until resolution, until the condition stabilizes, until the event is 
otherwise explained, whichever occurs first. All AEs and SAEs documented at a previous visit/contact 


and designated as ongoing, will be reviewed at subsequent visits/contacts, where the designation may 
remain ongoing. The investigator will ensure that the follow-up includes any supplemental investigations 
as may be indicated to elucidate the nature and/or causality of the SAE. This may include additional 
laboratory tests or investigations, histopathological examinations, or consultation with other health care 
professionals. SAEs that are ongoing at the time of the subjects final study visit/contact will be 
documented as ongoing. 
DSMP. 
The PI will be responsible for data and safety monitoring during the study. A physician not affiliated with 
the research proposal will serve as independent compliance officer and will review quarterly compliance 
with inclusion/exclusion criteria, gender and minority, adverse events. The results of the review will be 
reported to the PI and the IRB. 
 
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