Non-toxic goitre: diagnostic role of aspiration cytology, antibodies and serum thyrotrophin.

Fifty cases of bilateral non-toxic goitre, largely unselected, have been studied using fine needle aspiration cytology (without local anaesthesia); four techniques of thyroid antibody tests; serum thyroid biochemistry (including radioimmunoassay of TSH) and clinical evaluation. Autoimmune thyroiditis was found cytologically in 64%; simple colloid goitre in 24%; subacute thyroiditis of de Quervain in 10%. Aspiration cytology was the most sensitive means of detecting autoimmune thyroiditis and subacute thyroiditis. Two antibodies directed against the intra-cellular cytoplasmic antigen--the complement fixation test and an immunofluorescent antibody were of lesser value in detecting autoimmune thyroiditis (80% positivity) though equal to each other. Serum TSH was of some value--being elevated in 63% of cases of autoimmune thyroiditis and in no cases of simple colloid goitre. Two major cytological subtypes of autoimmune thyroiditis have been described--with significant differences in duration of goitre, mode of presentation, frequency of hypothyroidism, and response to thyroxine therapy. The high frequency of autoimmune thyroiditis in this series suggests that endemic goitre is unlikely in Western Australia.