Radioiodine therapy with iodine-131 is a nuclear-medicine treatment used for selected differentiated thyroid cancers that retain iodine uptake. German university nuclear-medicine departments document its use after thyroid surgery in defined risk settings and for selected iodine-avid recurrent or metastatic disease. It is not a universal thyroid-cancer treatment and should not be requested before the histology, surgical result, risk profile and iodine-related treatment indication have been reviewed.
First confirm that the tumor type can follow a radioiodine pathway
Heidelberg notes that papillary and follicular differentiated thyroid cancers can be treated with radioiodine because they may retain iodine metabolism, while anaplastic thyroid cancer does not. The German nuclear-medicine team therefore needs the exact pathology before deciding whether I-131 is relevant.
Radioiodine often follows surgery rather than replacing it
Freiburg and Essen describe radioiodine after surgery for differentiated thyroid carcinoma, with the exact indication based on individual risk. The nuclear-medicine episode should therefore be coordinated with the endocrine-surgery and pathology findings rather than booked as a standalone therapy from the diagnosis name alone.
Preparation includes thyroid-stimulation and iodine-exposure planning
Freiburg documents preparation using thyroid-hormone withdrawal or recombinant TSH depending on the individual plan and emphasizes avoiding significant iodine exposure before treatment. Recent iodinated contrast, iodine-containing medicines or supplements can therefore affect scheduling and must be disclosed to the treating team.
Treatment is delivered as an inpatient nuclear-medicine stay
Freiburg states that radioiodine therapy for malignant thyroid disease is performed during inpatient admission and typically includes radiation measurements and post-treatment whole-body imaging with SPECT/CT. Essen likewise documents inpatient radioiodine therapy and risk-adapted follow-up. Travel dates should therefore be based on the center's radiation-protection discharge criteria rather than a fixed number of nights copied from another patient.
Post-therapy imaging can influence the next step
Whole-body scintigraphy and, where used, SPECT/CT help document iodine-avid tissue after treatment. The findings are interpreted together with pathology, thyroglobulin, ultrasound and other imaging to determine surveillance or whether another treatment episode is considered.
Repeat radioiodine is not automatic
Essen publishes risk-adapted subsequent radioiodine and diagnostic follow-up. A previous I-131 treatment does not mean another cycle is automatically useful; the center must assess response, iodine avidity, cumulative treatment history and the wider disease course.
Records to send before a radioiodine request
The nuclear-medicine team should receive enough information to confirm indication, timing and preparation.
- Differentiated thyroid-cancer pathology
- Thyroidectomy and lymph-node operative reports
- Recent TSH, thyroglobulin and thyroglobulin-antibody results when available
- Neck ultrasound and current staging imaging
- All prior I-131 treatment dates and administered activities
- Prior post-radioiodine whole-body scans or SPECT/CT
- Recent iodinated CT contrast exposure
- Current thyroid-hormone medication
- Pregnancy/breastfeeding status where relevant to safety assessment
- A clear question about ablation, recurrence, metastases or repeat therapy
Sources and review
This guide was last source-reviewed on 2026-08-30.
- Radioiodine therapy for malignant thyroid disease — University Medical Center Freiburg ↗
- Thyroid clinic and long-term thyroid cancer follow-up — University Medical Center Freiburg ↗
- Radioiodine therapy for thyroid carcinoma — University Hospital Essen ↗
- Radioiodine therapy for differentiated thyroid carcinoma – referral pathway — University Hospital Essen ↗
- Thyroid cancer – subtype and radioiodine distinction — Heidelberg University Hospital ↗