Brown Adipose Tissue Activity and Thyroid Hormone
Condition: Hypothyroidism; Hyperthyroidism; Obesity
MeSH terms: Hypothyroidism; Hyperthyroidism
Study type: Interventional

Summary: 
      Rationale: During the last decades, research in possible therapies for existing obesity and
      developmental factors causing obesity has explosively increased. Recently renewed interest
      aroused for a tissue playing a possible role in both development and therapy for obesity:
      brown adipose tissue (BAT).

      To define the relation between BAT and thyroid hormone, the investigators set up the
      following research protocol. In this protocol BAT activity will be determined in subjects
      that underwent thyroidectomy for well-differentiated thyroid carcinoma.

      Objective: To study the effect of thyroid hormone and thyroid-stimulating hormone on brown
      adipose tissue activity.

      Study design: Determine BAT activity after thyroidectomy in well-differentiated thyroid
      carcinoma patients.

      Study population: Patients that underwent thyroidectomy for well-differentiated thyroid
      carcinoma, male and female, aged 18-65 years.

      Intervention: FDG-PET-CT-imaging ([18F]fluorodeoxyglucose positron-emission-tomography
      computed-tomography) of BAT activity will be performed under cold stimulation twice.

      For patients clinically withdrawn from thyroid hormone suppletion, the first occasion will be
      in a hypothyroid state within 4-6 weeks after thyroidectomy and the second measurement will
      take place in a euthyroid state 4 months after the start of thyroid hormone treatment.

      For patients receiving recombinant-thyroid-stimulating-hormone injections, the first occasion
      will be shortly after the injection in a state of high thyroid-stimulating hormone levels.
      The second measurement will be in a euthyroid state 4 months after the injection.

      Main study parameters/endpoints: The main endpoint of this study is the effect of thyroid
      hormone and thyroid-stimulating hormone on BAT activity in kBq (kilobecquerel) and SUV
      (standard uptake value). Secondary endpoints are the effects of thyroid hormone and
      thyroid-stimulating hormone on energy metabolism, body core temperature, skin surface
      temperatures and skin perfusion.

      Nature and extent of the burden and risks associated with participation, benefit and group
      relatedness: The absorbed radiation dose from the FDG PET-CT scan after administration of 74
      MBq (megabecquerel) of 18F-FDG is 2.8 mSv (miliSievert).
    


Intervention name(s): Levothyroxine therapy (137.75 ± 23.75 μg/day)
Intervention type(s): Other
Intervention description(s): This study was a longitudinal study in an academic center, with a follow-up period of 6 months. Ten patients with well-differentiated thyroid carcinoma eligible for surgical treatment and subsequent radioactive iodine ablation therapy were studied in a hypothyroid state after thyroidectomy and in a subclinical hyperthyroid state (TSH-suppression according to standard treatment protocol).
Allocation: Non-Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Basic Science