Radioactive iodine (I-131) in the treatment of hyperthyroidism in hilly terrains: An initial experience

Full text: We present our initial experience of treating patients of hyperthyroidism with radioactive iodine (RAI) in the hilly area of India, which falls, under endemic zone of iodine deficiency (sub Himalayan zone). People here have largely switched over to iodized salt to supplement the iodine intake in the food. It has shown remarkable regression in goitre and thyroid disorders. RAI (I-131) has been in use successfully for more than 60 years for the treatment of hyperthyroidism that may be due to Graves' disease (diffuse toxic goitre), toxic multi nodular goitre or solitary toxic nodule. After the treatment with I-131, these patients are followed up at interval of 6 and 12 weeks initially followed by 3 months for the first year and then 6-12 months henceforth. This is the only facility to treat patients of thyrotoxicosis with RAI in our area. Physicians used to treat such patients with drugs or surgery before the availability of RAI (I-131). But with availability of the facility for administering RAI since mid 2000 and increased awareness regarding its advantage of definite treatment, low cost, and easy administration with better compliance in hilly area where regular follow-up and cost are quite consideration, has made it quite popular among the referring doctors. In our centre emphasis was made on the treatment options available to doctors and patients explaining the advantages vs. disadvantages for the various modalities. The objective of this abstract is to show the outcome of treatment given to patients since so far. Total 108 patients referred for RAI treatment have been treated so far from August 2000 till March 2005 with 136 doses administered which consisted of 22 males and 86 females with age range from 28-64 yrs (mean age-43.1 yrs) and 19-70 yrs (mean age- 42.7 yrs) respectively. 87 patients were given single dose, while 21 patients required 2 or more doses to achieve euthyroid status. Re-treatment was done not before 3 months after first administration if there was evidence of residual disease on clinical and biochemical status. 15 of the 108 patients were excluded from this study, as their follow up period was less than 3 months. Remaining 93 patients underwent regular follow-ups. 33 out of these 93 patients developed hypothyroidism during the period ranging from 2.5 months to 42 months post RAI administration (35.5%). Majority of them (28/33) developed hypothyroidism with in 1 yr of post RAI (84.4%) while remaining developed hypothyroidism after 1 yr. Earliest appearance of hypothyroidism in patient was at 3 months that were promptly treated with L-thyroxin. Average amount of iodine-131 /dose given was 6.2 mCi. Doses of RAI (I-131) administered ranged from 3.3 mCi (minimum) to 20 mCi (maximum) in different patients during the course of treatment. All these patients are still undergoing periodic follow-up without any significant side effect. The result of this study shows that I-131 is safe and cost effective method to treat hyperthyroidism. (author)