Metabolism and Thyroid Hormone Changes During Exposure to Cold Temperatures

Completed · Not applicable

Conditions studied: Obesity

In brief

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 Fat tissue biopsy: A small piece of fat tissue is withdrawn through a needle from under the skin on the abdomen.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.

Key facts

Study ID

NCT00521729

Run by

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

People needed

160

Starts

2007-08-24

Expected to finish

2018-06-26

Last updated by the study team

2019-12-16

Who can join

Age: 18 and older, up to 60. Sex: any. Healthy volunteers: not accepted.

You may not qualify if…

• 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 35 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

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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