Etiology of adult goiter in Taiwan--a hospital-based study.

We studied the etiology of goiter on outpatient clinic basis with thyroid function test, measuring circulating thyroid autoantibodies and urinary iodine excretion. One hundred patients from endocrine and metabolic clinic with grade I or over goiter according to the WHO classification were included by random sampling after carefully excluding the pure thyroid cyst and thyroid cancer by sonographic examination and fine needle aspiration cytology. Among these 100 studied cases, 23 were classified as Graves' hyperthyroidism (group 1), 19 autoimmune thyroiditis (group 2), 14 simple goiter (group 3), 42 nodular goiter (group 4) and 2 subacute thyroiditis. All four groups of goiter showed female predominance. The mean +/- SD age and 24-hour % RAIU for these four groups were 33.9 +/- 14.5 and 64.3 +/- 24.4; 44.6 +/- 19.5 and 27.3 +/- 11.3; 37.5 +/- 15.9 and 27.5 +/- 9.0; and 47.5 +/- 16.4 and 36.1 +/- 16.7, respectively. Patients with Graves' hyperthyroidism were significantly younger in age than the nodular goiter group and had higher RAIU than the other three groups (p less than 0.05, Kruskal-Wallis ANOVA, multiple comparisons). There was no age or RAIU difference among groups 2-4. The amount of urinary iodine excretion distributed in a very wide range and exhibited no significant difference among four groups. Only 2 subjects had urinary iodine excretion below 50 micrograms iodine/g creatinine but 50% (49.3% of group 2-4) had urinary iodine excretion higher than 300 micrograms iodine/g creatinine. Iodine deficiency is not a real problem at present.(ABSTRACT TRUNCATED AT 250 WORDS)