Introduction: typically hyperthyroidism has been more often associated with the female gender. There is a large female predilection (male:female sex ratio up to 1:10), with little documentation in the literature about wholly male hyperthyroid populations. A male incidence of 0.7 per 100, 000 has been reported for South African men while the women have a relatively higher rate of 0.02. There is no documented evidence of differences between male and female genders in response to treatment of PH with radioactive iodine (RAI), although operational evidence suggests that hyperthyroidism in males is less amenable to RAIT than females. This study therefore proposed to evaluate male hyperthyroid patients with Graves' disease (GD) treated at our facility, for factors affecting outcome of RAIT.

Methods: this is a retrospective analysis of records of hyperthyroid patients who were treated with RAI over a 19-year period at a university teaching hospital, in the Western Cape of South Africa.

Results: the overall cure rate was 76.4% for these male patients. Cure was observed as euthyroidism in 31 patients (15.3%) and hypothyroidism in 129 (63.5%). Age, thyroid uptake, severity of hyperthyroidism, previous antithyroid drug (ATD) usage, administered quantity of RAI, ethnicity and patients' pulse at presentation were not significant in influencing outcome.

Conclusion: factors which have been evaluated as affecting outcome of RAIT were unimportant in these patients. Despite the mainly hyperthyroid presentation of the patients, RAIT was so effective that the main type of cure after therapy was hypothyroidism.