Metabolism and Thyroid Hormone Changes During Exposure to Cold Temperatures - Full Text View

Sponsored by:	National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Information provided by:	National Institutes of Health Clinical Center (CC)
ClinicalTrials.gov Identifier:	NCT00521729

Purpose

This study will examine how body metabolism adjusts to small changes in environmental temperature and how it may be related to weight loss.

Healthy, non-obese individuals between 18 and 60 years of age may be eligible for this study. The study consists of one screening visit and one 5-day admission to the NIH Clinical Center for the following procedures:

Diet: Participants follow a proscribed diet consisting of 50% carbohydrates, 20% protein and 30% fat.

DEXA scan to measure body fat. Subjects lie on a table above a source of X-rays while a very small dose of X-rays is passed through the body.

Air displacement plethysmography (Bod-Pod) to study fat composition: Subjects sit in a small booth for 10 minutes wearing a swim suit and breathing normally through a tube. This test measures the person's weight and volume precisely.

Metabolic room: Subjects stay 12 hours in a specialized room designed to measure the amount of oxygen breathed in and the amount of carbon dioxide breathed out. The room contains a private toilet and sink, treadmill, bed, desk, window, telephone and computer with television and internet access.

While in this room, subjects undergo the following:

Continuous heart rate monitor: Subjects wear an EKG monitor to analyze heart rate variability.
Spontaneous movements: Subjects wear portable accelerometers at the hip and wrist to measure spontaneous physical movements.
Continuous temperature monitor: Subjects swallow a small capsule that transmits internal body temperature via miniature, wireless sensors. Adhesive patches placed on the skin monitor external body temperature.
Blood and urine collections: Subjects collect all of their urine during the 12 hours they are in the metabolic room. Blood samples are taken at specified intervals through a catheter that has been placed in a vein.
Microdialysis: A small needle is placed into fat tissue just under the skin on the abdomen. A solution containing a minimal amount of ethanol is infused and samples of fluid are collected every 20 minutes as it leaves the fat pad. This helps determine the metabolism level. This procedure starts 30 minutes before entering the metabolic room and continues until the subject leaves the room.

Fat tissue biopsy: A small piece of fat tissue is withdrawn through a needle from under the skin on the abdomen. The sample is used to study fat tissue size and ability to store sugar....

Condition	Intervention
Obesity	Procedure: Exposure to Cold Temperature

MedlinePlus related topics: Diets Obesity

Drug Information available for: Thyroid hormones Thyroid

U.S. FDA Resources

Study Type:	Interventional
Study Design:	Randomized, Single Blind, Placebo Control, Crossover Assignment, Efficacy Study
Official Title:	Thyroid Hormones Homeostasis and Energy Metabolism Changes During Exposure to Cold Temperature in Humans

Further study details as provided by National Institutes of Health Clinical Center (CC):

Primary Outcome Measures:

Changes in energy expenditure and in thyroid hormone levels

Secondary Outcome Measures:

Changes in spontaneous physical activity and in thermic effect of food

Estimated Enrollment:	25
Study Start Date:	August 2007

Intervention Details:

N/A

Detailed Description:

Thyroid hormones play an important role in the modulation of energy metabolism by regulating the rate of thermogenesis, i.e. the amount of heat produced to maintain the stable core temperature of the organism. Clinically, hypo- and hyperthyroidism are associated with major changes of thermoregulation and energy expenditure. While in rodents the ability of thyroid hormones in regulating the temperature and energy expenditure in response to changes of temperature is well known, its actual role in humans is poorly understood. We hypothesize that humans will respond to exposure to moderate cold by increasing the energy expenditure mediated by the thyroid hormones' action and, at the same time, by decreasing the heat dispersion. This randomized, cross-over study is aimed to analyze the changes in the thyroid hormones, energy expenditure and stress hormones in response to exposure to mild changes in environmental temperature.

Eligibility

Ages Eligible for Study:	18 Years to 60 Years
Genders Eligible for Study:	Both
Accepts Healthy Volunteers:	Yes

Criteria

INCLUSION CRITERIA:
Age greater than or equal to18 and less than 60 years, male or female
Written informed consent

EXCLUSION CRITERIA:

Hypo- or hyper-thyroid (history or TSH greater than 5.0 and less than 0.4 miU/L)
Blood pressure greater than 140/90 mmHg or current antihypertensive therapy
History of cardiovascular disease
BMI less than or equal to 20 or greater than or equal to 27 Kg/m(2)

Diabetes mellitus (fasting serum glucose X greater than 126 mg/dL)

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
Iron deficiency (Ferritin less than 40 ng/mL males, and less than 20 ng/mL females)
Renal insufficiency or estimated creatinine clearance less than or equal to 50 mL/min (MDRD equation)
Claustrophobia
History of illicit drug or alcohol abuse within the last 5 years; current use of drugs (by history) or alcohol (CAGE greater than 3)
Psychiatric conditions or behavior that would be incompatible with safe and successful participation in this study
Current use of medications/dietary supplements/alternative therapies known to alter thyroid function
Current use of antiplatelet or anticoagulants
Allergy to lidocaine
Pregnancy/breastfeeding/hormonal contraception and childbirth within the last 24 months
Perimenopausal (as self-described within two years from onset of amenorrhea or current complaints of hot flashes)
Current smoker or user of tobacco products

Contacts and Locations

Please refer to this study by its ClinicalTrials.gov identifier: NCT00521729

Contacts

Contact: Patient Recruitment and Public Liaison Office	(800) 411-1222	prpl@mail.cc.nih.gov
Contact: TTY	1-866-411-1010

Locations

United States, Maryland
National Institutes of Health Clinical Center, 9000 Rockville Pike	Recruiting
Bethesda, Maryland, United States, 20892

Sponsors and Collaborators

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

More Information

Additional Information:

NIH Clinical Center Detailed Web Page This link exits the ClinicalTrials.gov site

Publications:

Hill JO. Understanding and addressing the epidemic of obesity: an energy balance perspective. Endocr Rev. 2006 Dec;27(7):750-61. Epub 2006 Nov 22. Review.

Rosen ED, Spiegelman BM. Adipocytes as regulators of energy balance and glucose homeostasis. Nature. 2006 Dec 14;444(7121):847-53. Review.

Katzmarzyk PT, Leonard WR. Climatic influences on human body size and proportions: ecological adaptations and secular trends. Am J Phys Anthropol. 1998 Aug;106(4):483-503.

Study ID Numbers:	070202, 07-DK-0202
Study First Received:	August 25, 2007
Last Updated:	March 27, 2009
ClinicalTrials.gov Identifier:	NCT00521729 History of Changes
Health Authority:	United States: Federal Government

Keywords provided by National Institutes of Health Clinical Center (CC):

Thyroid
Thermoregulation
Catecholamines
Energy Expenditure

Obesity
Healthy Volunteer
HV

Study placed in the following topic categories:

Body Weight
Signs and Symptoms
Obesity
Nutrition Disorders

Overweight
Overnutrition
Healthy
Hormones

Additional relevant MeSH terms:

Body Weight
Signs and Symptoms
Obesity

Nutrition Disorders
Overweight
Overnutrition

ClinicalTrials.gov processed this record on May 07, 2009