Age and gender predict the outcome of treatment for Graves' hyperthyroidism

The response to treatment in Graves' hyperthyroidism is unpredictable, and factors postulated to predict outcome have not generally proved clinically useful or been widely adopted in clinical practice. We audited outcome in 5 36 patients with Graves' hyperthyroidism presenting consecutively to determ ine whether simple clinical features predict disease presentation and respo nse to treatment. At presentation males had slightly more severe biochemica l hyperthyroidism [free T-4: males, 64.3 +/- 3.0 pmol/L (mean +/- se); fema les, 61.3 +/- 1.7 (P = 0.45); free T-3: males, 24.3 +/- 1.5 pmol/L; females , 21.0 +/- 0.6, (P = 0.04)]. Patients less than 40 yr at diagnosis had more severe hyperthyroidism than patients more than 40 yr old [free T-4: <40 yr , 64.3 +/- 2.0; >40 yr, 56.7 +/- 2.3 (P = 0.02); free T-3: <40 yr, 22.8 +/- 0.8; >40 yr, 19.0 +/- 0.9 (P = 0.003)]. Males had a lower remission rate t han females after a course of antithyroid medication [19.6% us. 40%; odds r atio, 0.37; 95% confidence interval (CI), 0.17-0.79; P < 0.01]. Similarly, patients aged less than 40 yr had a lower remission rate than older patient s (32.6% vs. 47.8%; odds ratio, 0.53; 95% CI, 0.32-0.87; P 0.01). One dose of radioiodine cured hyperthyroidism in fewer males than females (47% vs. 7 4%; P < 0.0001). Logistic regression analysis demonstrated male sex (odds r atio, 2.80; 95% CI, 1.31-5.98; P = 0.008), serum free T-4 concentration at diagnosis (odds ratio, 1.02; 95% CI, 10-1.04; P = 0.01), and dose of radioi odine administered (odds ratio, 0.99; 95% CI, 0.99-1.00; P = 0.001) were co ntributing factors associated with failure to respond to a single dose of r adioiodine. As males and younger patients are more likely to fail to respon d to medical treatment, and male patients are likewise less likely to respo nd to a single dose of radioiodine, we suggest that those groups with low r emission rates should be offered definitive treatment with radioiodine or s urgery soon after presentation and that the value of higher initial doses o f radioiodine in males be evaluated.