THYROID VOLUME AND FUNCTION AFTER I-131 TREATMENT OF DIFFUSE NONTOXICGOITER

OBJECTIVE Traditional treatment modalities of diffuse non-toxic goitre are thyroid hormone suppression or surgery. When treating nodular non -toxic goitre with I-131 treatment a reduction in thyroid volume to ab out 50% has been observed. In the present study we evaluated the effec t of I-131 treatment of diffuse non-toxic goitre. DESIGN Retrospective study of patients treated for a diffuse non-toxic goitre and followed by evaluation of thyroid volume measured by ultrasound. PATIENTS Ten selected patients from our out-patient clinic with diffuse non-toxic g oitre. MEASUREMENTS Thyroid volume was measured by ultrasound and thyr oid function by serum values of T4, T3, T3 uptake ratio, TSH, TSH rece ptor antibodies and thyroid peroxidase antibodies (anti-TPO). Measurem ents were performed before and 1, 3, 6 and 12 months (and 18 months (n =7), thyroid volume measured in six patients)) after I-131 treatment. RESULTS Thyroid volume declined in ail patients from median 41 (range 27-160) ml to 20 (range 9-108) ml over 1 year, a reduction of 47%. One patient developed transient and one persistent hypothyroidism in the follow-up period. Both had elevated anti-TPO levels before treatment ( 331 and 9185 U/ml) and demonstrated titre increases of 2.5 and 30 time s after 3 and 6 months, respectively. Pretreatment values were reached after 1 year. The other eight patients had normal anti-TPO levels and free T4 and T3 indices did not change during follow-up, whereas serum TSH revels demonstrated upward trends within the normal range (P < 0. 05). TSH receptor antibodies were normal and remained so in all patien ts. CONCLUSIONS I-131 treatment of diffuse non-toxic goitre reduces th yroid volume by approximately 50% within 12-18 months. Hypothyroidism, during a limited follow-up period, developed only in patients with po sitive anti-TPO levels before treatment.