The study aims at clarifying (in a randomized, double-blinded design):

1. Whether stimulation with 0.1 mg rhTSH 24, 48 or 72 hours before induction of a 131I-tracer dosis increases the 131I uptake in patients with atoxic multinodular goitre and to study which time interval is the most optimal (Part I)
2. Whether patients suffering from atoxic multinodular goitre obtains a corresponding goitre reduction compared with a control group when stimulating with 0.1 mg rh TSH 24, 48 or 72 hours before 131I therapy and when reducing the thyroid radiation dose to 50 Gy (Part II)

The two studies will be carried out successively on the same patient population. The 131I uptake will be carried out first followed by the I therapy itself. The patients are compared with a placebo-treated control group going through the same course of treatment, but the 131I dosis will be 100 Gy (standard treatment). After the 131I therapy, all patients are followed during one year with a regular ultrasound scan of the thyroid gland and control of the metabolic status. The patient satisfaction is monitored by the use of a visual-analogue-scale.

Inclusion Criteria:

• Age over 18 years
• Apart from benign non-toxic goiter no other serious illness
• Signed proof of participation

Exclusion Criteria:

• Treatment with Levothyroxine
• Former 131I-therapy
• A thyroid volume above 100 ml or a retro-clavicular component
• Unsafe contraception
• Pregnancy or breastfeeding
• Participation in another clinical trial
• Previous allergic reaction toward rhTSH
• Suspicion of malignancy in the thyroid gland either by clinical examination, laboratory findings (a raised serum calcitonin or ionized calcium)or by fine-needle aspiration biopsy
• Physically or mental condition making it impossible to participate
• Acute ischemic heart attach within the last 3 months
• Alcohol and/or drug addicts