This study is focused on measuring mitochondrial activity of human brown adipose tissue. During surgery, adipose tissue biopsies from white and brown adipose tissue will be collected from the deep neck area. These biopsies will be used to examine mitochondrial function via histological analysis, biochemical analysis and in vitro experiments based on precursor cells present in the biopsies.

Inclusion Criteria:

• Indication for surgery in the supraclavicular and neck region (more specific patients diagnosed with hyperparathyroidism, struma, benign thyroid gland tumours, implantation of a vagal neurostimulator for epilepsia and cervical neurologic disorders)
• In the thyroid gland group, euthyroid function

Exclusion Criteria:

• Pre-operatively diagnosed malign tumour
• Patients undergoing acute surgery because of critical illness

Patients indicated for surgery in the supraclavicular and neck region