Nuclear Medicine Clinic
University of California, Los Angeles
Guidelines for I-131 Therapy in Differentiated Thyroid Cancer

The UCLA Nuclear Medicine Clinic performs the treatment of Thyroid Cancer with radio-active iodine (RAI) on a consultation basis.   Physicians may refer patients to the Nuclear Medicine Clinic for treatment.  
Licensed physicians are authorized to use I-131 in the State of California.  At UCLA Medical Center, only Nuclear Medicine specialists are authorized to treat patients with radionuclides.

The treatment strategy for Differentiated Thyroid Cancer is based on a Fixed Dose regimen, conform the guidelines of the Society of Nuclear Medicine    (http://www.snm.org)

Dose of I-131 sodium iodide

Remnant ablation (post-op) 
	Low Risk 	50 mCi   
	High Risk 	100 mCi

Regional Lymph Node metastasis 	150 mCi

Distant Metastasis 	200 mCi

The above doses can be administered on an outpatient basis.  Written radiation safety guidelines will be given to the patient.
RAI doses > 200 mCi require hospital admission.

Ablation of Thyroid Remnants
For the first treatment, or remnant ablation 6-8 weeks post-op, a diagnostic scan is not necessary.  The pathology report is sufficient to determine the therapeutic dose.
Low risk means no capsular invasion and no vascular invasion. High-risk are all others without evidence of local or distant metastasis.

Follow-up treatment
For every other RAI therapy, i.e. not shortly after (sub)-total thyroidectomy, a diagnostic scan must be performed to assess the presence and extent of iodine-avid disease.  This diagnostic scan will determine the therapeutic dose to be administered.  

Advisory

1	Patients should be referred by the UCLA Endocrinology service (adult or pediatric), or known Endocrinologists from the community.  General practitioners and family practice physicians should be advised to refer patients via our Endocrinology service.

2	Outside referrals need to include a copy of the clinical assessment and pathology report before the patient can be considered for the first treatment.

3	A “prescription” for a radioiodine pill or dose does not exist.  Only consultations and referrals for treatment can be accepted.

4	In case of “iodine negative & thyroglobulin positive” patients an FDG-PET scan may be considered before treatment.

Patient Preparation 

•	Remnant Ablation 
Start Cytomel post op and continue for 3-4 weeks, stop 10-14 days prior to diagnostic or treatment dose.    
•	Loco-regional Disease or Metastasis, Surveillance scan
Stop Levothyroxine, start Cytomel for 3-4 weeks, stop 10-14 days prior to diagnostic dose.                                                                                            
•	Stimulation Protocol with Thyrogen
Not FDA approved for treatment. Consider if contraindications to thyroid hormone withdrawal. Thyrogen 0.9 mg IM for 2 days and treat on 3rd day.
	    
•	Low Iodine diet starting 10 days prior to dose

•	Interfering drugs and interval before treatment:

Medication	Length	
Multi vitamins	10 days	
Topical iodine	4 weeks	
SSKI/ Kelp/ Expectorants/ Lugol's Solution	4 weeks	
CT with IV contrast / Angiogram	8 weeks if normal renal function	
Amiodarone	9 months	

Restrictions/Follow-up
•	Activity restrictions should be followed for 72 hrs after the therapeutic dose administration (even if safe to discharge from hospital).
•	Resume regular diet and thyroid medications 72 hrs after therapy dose.
•	Patients return to Nuclear Medicine 7-14 days following treatment with I-131 for a Whole Body scan.

Special Cases
•	If a diagnostic whole body I-131 scan is positive, further anatomic imaging is recommended to evaluate the possibility of surgical resection. If no surgically resectable disease is identified, thyroid hormone withdrawal and treatment is recommended. 
•	iodine negative & thyroglobulin positive patients are still candidates for treatment.  FDG-PET may be considered before treatment to assess surgical options.
•	I-131 treatment is recommended prior to external beam radiation therapy unless the Whole Body iodine scan is negative.