Graves thyrotoxicosis is a common autoimmune disease. Patients suffer at diagnosis from weight loss, increased heart rate and stress intolerance. Some patients have difficulties in regaining quality of life. Diagnosis is found through elevated thyroid hormones thyroxin, suppressed TSH (thyroid stimulating hormone) from the pituitary and elevated stimulatory antibodies, TRAb (thyrotropin receptor antibody) to the thyroid. Selenium is sparse in western Europe. This compound has important function in thyroid hormone metabolism and on the immune system. It is not known whether addition of selenium affects the well being of patients with Graves´thyrotoxicosis. The subject of this study is to investigate this

In the County of Södermanland we include 44 patients with Graves´thyrotoxicosis. They are treated with methimazole and thyroxin, and randomised to selenium or placebo. Neuropsychological investigation is performed, before medical treatment is commenced and repeated after 9 month. Serum concentration of thyroid hormon levels, autoantibodies and selenium are followed.

Inclusion Criteria:

• New diagnose of autoimmune thyrotoxicosis
• biochemically proven with increased thyroxin
• low TSH and elevated TRAb/or positive scintigraphy.
• Age 18 - 55. Willing to participate -

Exclusion Criteria:

• No previous head trauma,
• No difficulties with swedish language,
• No medication which could affective neuropsychological testing,
• No planned or ongoing pregnancies.
• Normal intellectual capacity.
• No severe ophthalmopathy, or other severe disease