Endocrine Abstracts

We have previously shown that the current guidelines for monitoring thyroid function post radioiodine (RI), may not detect hypothyroidism until it has become severe, in a significant proportion of cases (J Endocrinol Invest 2012 35 82–86). An alternative more intense follow-up strategy was used whereby patients had TSH and FT₄ measured at 4-week intervals post RI for 6 months. Endocrine specialist nurse-led telephone and nurse-led out-patient clinics were utilized. Data was collected prospectively in 104 patients who received RI for hyperthyroidism. 101 patients were treated with single dose of RI (mean 466 MBq) and three patients received as second dose (mean 550 MBq). Results from this study were compared to our previously published data which used traditional follow-up. We found 75 patients (72%) developed hypothyroidism during the first 6 months of follow-up. Hypothyroidism was detected in 16% of the patients at <4 weeks, 36% at 4–<8 weeks, 28% at 8–<12 weeks, 12% at 12–<16 weeks, 3% at 16–<20 weeks and 5% at 20–<24 weeks. At first detection of hypothyroidism, during intense follow-up, 8/75 patients (11%) had TSH >50 mU/l compared to 44/124 (36%) using our previous data during traditional follow-up (P<0.001) and 11/75 patients (15%) had FT₄ <5 pmol/l compared to 34/124 (27%) using our previous data during traditional follow-up (P <0.03). Comparing intense follow-up with traditional follow-up; median TSH was 11 mU/l vs 32 mU/l (P<0.005) and median free T₄ was 8 vs 7 pmol/l (P<0.02) when hypothyroidism was first detected. We conclude that using a more intense follow-up protocol post RI, we can detect hypothyroidism at an earlier and less severe stage.