Summary

The case records of 262 patients who received 131l therapy during a 6-year period were analysed retro-spectively. These included seventy-eight patients who received more than one therapeutic dose. The major indication for 131I therapy was thyro-toxicosis occurring in patients aged 40 years and over. The racial incidence in this series is striking. The effects on thyroid function of two low-dose schedules (4 mCi and 6 mCi) were compared. The major complication encountered was hypothyroidism. 4 mCi appears to be as effective as 6 mCi with the added advantage of producing less hypothyroidism. RADIOACTIVE iodine is now an integral part of the therapy of thyrotoxicosis in selected cases. Since the earlier reports of the work of Balls et al. (1955), Beierwaltes & Johnson (1956) and Chapman & Maloof (1955), much data has accumulated con-cerning the indications for, dosage of and complica-tions following 131I therapy. Discrepancies between the many reports available concerning the various factors involved with 131I administration has prompted us to evaluate our experience at Groote Schuur Hospital over a 6-year period (January 1965-March 1971). Subjects and methods 344 thyrotoxic patients received 131I during the period January 1965-March 1971. The case records of 262 patients were available for retrospective analy-sis as regards age, sex, race and indications fo