Effectiveness of fixed dose radioactive iodine (RAI) for the treatment of hyperthyroidism: experience of a teaching hospital in south west Nigeria

OBJECTIVE: Using radioactive iodine (RAI) as first line therapy for Graves’ hyperthyroidism and as the treatment of choice for relapsed Graves’ disease is increasing in recent times. However, there has been little consensus on the most appropriate dose to use.
So this study is to determine the response of hyperthyroidism to fixed doses of 370 MBq and 555 MBq RAI therapies and determine the incidence of hypothyroidism at 6months post therapy.

METHODS: Hyperthyroid patients’ case records treated with radioiodine to determine response rate of hyperthyroidism to the two fixed dose regimens was retrospectively reviewed. Statistical analysis was with SPSS version 15.0. And the level of statistical significance was taken as P < 0.05.
Forty subjects, 6 males (15%) and 34 females (85%) received RAI therapy for Graves’ hyperthyroidism, mean age 49.4 years (range, 25-75years). The thyroid function status at 6months post therapy was available for all subjects. 24 patients (60%) received 370 MBq while 16 patients (40%) received 555 MBq.

RESULTS: The response for fixed doses of 370 MBq and 555 MBq were similar (100%). Also, the incidence of hypothyroidism in these subjects was 66.6% with fixed dose of 370 MBq and 62.5% with fixed dose of 555 MBq within 6months post RAI therapy were similar.
CONCLUSION: RAI is highly effective for the treatment of hyperthyroidism, with a cure rate of 100%. However, it has proved impossible to determine a fixed dose regimen for individual patients accurately to guarantee a euthyroid state. This is because hypothyroidism is a natural predictable sequel of RAI therapy.