This project has the following primary aims:

The main objective is to delineate the association between changes in Resting energy expenditure (REE) and QOL in hypothyroid patients before and after one year of L-T4 treatment. To achieve this, the investigators plan to compare newly diagnosed hypothyroid patients soon after diagnosis before L-T4 therapy has been initiated after 6 months and after 1 year of treatment.

Primary endpoint is changes in REE compared to changes in QOL Secondary endpoint is changes in cognitive function and changes in body composition before and after one year of treatment and furthermore changes in insulin resistance following changes in body composition and free fatty acids (FFA).

Subjects and Methods:

74 newly diagnosed hypothyroid patients of both genders and age between 20 and 75 years will be recruited from the out-patients clinic in Herlev and Gentofte Hospital and the general practitioners before start of substitution therapy. Participants will get an appointment immediately after diagnosis to avoid unnecessary delay of treatment. Shortly after diagnosis patients will undergo a test panel at the first experimental day, where patients arrives fasting.

• Psychological test using:

  • ThyPRO a thyroid-specific quality of life questionnaire(18),
  • Cognitive function by CALCAP® Abbreviated Test Battery,
  • Perceived cognitive deficit questionnaire (Perceived Deficits Questionaire)
  • Major Depression Inventory (MDI) questionnaire

• REE will be measured by a CCM-express calorimeter,

• DEXA-scan

• Blood samples will be taken and patients will be characterized through basic information.

• Insulin resistance will be assess through an oral glucose tolerance test (OGTT) At end of the first experimental day patients will start L-T4 therapy following national guidelines, with regular control of thyroid hormones to ensure optimal treatment. When patients are euthyroid and TSH is below 4 * 10-3 International Units pr liter (mU/l) patients will have blood samples monitored every 3 months for the rest of the trial.

After 6 and 12 months of treatment patients will undergo a similar experimental day and return to their general practitioner or outpatient clinic.

A control group of 18 matched healthy persons will undergo the first experimental day in the same way as the hypothyroid patients, except they do not start any kind of therapy and they only participate in the first experimental day.

Inclusion Criteria:

• TSH > 10 mU/liter

Exclusion Criteria:

• Serious competing illness
• Pregnancy or planning to become pregnant
• Thyroidectomized patients
• Unable to speak and understand danish

Hypothyroid patients.