Comparing to antithyroid drug or radioactive iodine therapy, surgical treatment of Graves's disease has several advantages such as, rapid and long lasting therapeutic effect, relatively low incidence of postoperative hypothyroidism and good
indication
to severe thyrotoxicosis in young patient. However, prognostic factors of thyroidectomy in Graves' disease are ontroversial. Because these prognostic factors have some effects on one another, surgeon has to consider them all together to have a
good
result.
The purpose of this study is to elucidate significant prognostic factors in sugery of Graves'disease and propose optimum surgical method withich is considered significant prognostic factors.
In retrospective study 75 patients, who were performed bilateral subtotal thyroidectomy at Seoul National University Hospital by same surgeon, were analyzed. Postoperative hypothyroidism was developed in 8(47.1%) of 17 patients with 4g of remnant
thyroid weight and 6(19.4%) of 31 patients, 3(11.1%) of 27 patients with 6g, 8g of remnant thyroid weight respectively(P<0.050). Fourteen(42.4%) of 33 patients with lymphocytic infiltration and 3(7.1%) of 42 patients without lymphocytic
infiltration
beame hypothyroid state (P<0.001). Recurrence of hyperthyroidism was developed in 6(20.0%) of 30 patients with persistently high level of postoperative TBII and none of 35 patients with normal postoperative TBII lever (P<0.01). As a result of
multivariated analysis(logistic regression procedure) the fewer the remnant weight is, the more postoperative hypothroidism was developed (P=0.0016). Lymphocytic infiltration was proved as sigaificant prognostic factor for postoperative
hypothyroidism,
also(P=0.0340). Considering thyroid remnant weight and lymphocytic infiltration simultaneously, 6g of remnant weight without lymphocytic infiltration, 8g of remnant weight with lymphocytic infiltration have resulted in best prognosis.
Upon the basis of this result, prospective randomized study was designed. Remnant thyroid weight was decided as the result of lymphocytic infiltration on frozen section. 4g and 6g of thyroid tissue was left in each 5 cases without lymphocytic
infiltration and 6g and 8g in same number with lymphocytic infiltration. Consequently, all 5 patients of 4g with lymphocytic infiltration developed hypothyroidism, and 1 hypothyroidism, 4 euthyroidism were developed in 6g without lymphocytic
infiltration(P<0.05). Four hypothyroidisms, euthyroidism were developed in 6g with lymphocytic infiltration and 4 euthyroidisms, 1 recurrence in 8g with lymphocytic infiltration (P<0.05).
Conclusively at the time of surgery of Graves' disease, if lymphocytic infiltration is positive on frozen section it is better to leave 8g of remnant thyroid weight and in case of negative lymphocytic infiltration, 6g may be the optimum remnant
weight.
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