Pharmacogenomic Response to Thyrotropin-Releasing Hormone Stimulation in Healthy Volunteers: The Influence of a Common Type 2 Deiodinase Genetic Polymorphism on Serum T3

Completed

Conditions studied: Thyroid Disease, Healthy

In brief

This study intends to examine how a common genetic pattern affects thyroid function. Recent studies have demonstrated that a substance (enzyme) produced by a gene has an important role in controlling circulating thyroid hormone levels. A commonly found pattern in this gene exists in many individuals and might affect the function of the enzyme. These individuals need higher doses of thyroid hormone medication in certain situations (e.g. in the treatment of thyroid cancer after the thyroid gland has been removed) than those individuals without the variation. We intend to study this by looking at the response to a hormone-test in healthy volunteers with different genetic patterns. We plan to screen healthy volunteers using a blood test to identify their genetic pattern relating to the enzyme we are interested in. From this group, forty-five healthy volunteers will be recruited for the hormone-test. This test (called the TRH test) uses a hormone produced by the brain and stimulates the pituitary and thyroid gland. The response to this test will allow us to compare the function of the thyroid system in relation to the genetic pattern of the volunteer. We hypothesize that the stimulation of the thyroid hormone system will be decreased in volunteers with a specific genetic pattern and that these individuals will release less active thyroid hormone from the thyroid gland in response to the TRH test. This study will provide new information on the effect of a common genetic pattern on thyroid hormone function and will help us to better understand the way in which the thyroid hormone system operates. Ultimately, the results of this study might help to provide a more individualized therapy for patients in need of thyroid hormone replacement.

Key facts

Study ID

NCT00812149

Run by

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

People needed

86

Starts

2008-12-17

Expected to finish

2014-05-16

Last updated by the study team

2017-10-06

Who can join

Age: 18 and older, up to 65. Sex: any. Healthy volunteers: not accepted.

You may not qualify if…

• BMI less than or equal to 19 or greater than or equal to 35 Kg/m(2)
• Hypothyroidism, or TSH levels above the normal limits (current replacement therapy or TSH greater than 4.0 mcIU/mL)
• Hyperthyroidism, or TSH levels below the normal limits (current or previous therapy or TSH less than 0.4 mcIU/mL)
• Autoimmune thyroid disease (as defined by a positive anti-TPO, or anti-TSH receptor antibody titer)
• Hypertension (Blood pressure greater than 140/90 or use of antihypertensive medication)
• Liver disease or ALT serum concentrations greater than 1.5 times the upper laboratory reference limit.
• Renal insufficiency or estimated creatinine clearance less than or equal to 50 mL/min (MDRD equation).
• History of, and/or current Diabetes Mellitus (fasting glucose greater than 126 mg/dL)
• Iodine deficiency (spot urine iodine concentration less than 42 mcg/L)
• History of, and/or current coronary artery disease
• History of, and/or current asthma
• History of, and/or current seizures or chronic headache
• History of, and/or current depression
• History of pituitary tumor
• Pregnancy (women of child-bearing potential must have a negative pregnancy test prior to inclusion and at the time of TRH testing)
• Known allergy to TRH
• Current use of prescription medication or certain non-prescription medications and dietary supplements which could affect thyroid function and/or metabolism.

Where it is running

• National Institutes of Health Clinical Center, 9000 Rockville Pike — Bethesda, Maryland, United States

Full record on ClinicalTrials.gov

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