[A study of biological and histological criteria of thyroid autoimmunity in diffuse goiters with hyperthyroidism]. / Etude des paramètres biologiques et histologiques d'autoimmunité thyroïdienne dans les goitres diffus avec hyperthyroïdie.

Hyperthyroidism is usually classified as follows: with diffuse or with toxic plurinodular goiter, respectively considered as autoimmune and non-autoimmune thyroid disorders. This classification seems partially inadequate as signs of thyroid immunity may be found in some plurinodular toxic goiter and alternatively may by lacking in some cases of Graves' disease. These observations led us to study the intensity of intrathyroidal autoimmune process (IAP) and the levels of TBIAb, TPO- and Thyroglobulin-antibodies in 105 cases with diffuse goiter, hyperthyroidism and elevated RAIU (92 women and 13 men, age 34 +/- 11, mean +/- SD). The intensity of intrathyroidal autoimmune process (IAP) was determined by one pathologist (HT) by semi quantitative method applicable to routine clinical use. Subtotal thyroidectomy was performed because of a large goiter (n = 29), a concomitant cold nodule (n = 20), a recurrent disease (n = 18), intolerance to antithyroid drugs (n = 5) or because patients chose surgical treatment (n = 33). All cases were rendered euthyroid at the time of surgery using antithyroid drugs or iodine. The results show a lack of IAP and undetectable levels of TBIAb, TPO- and Thyroglobulin-antibodies in 10%, 11%, 25% and 47% respectively. The intensity of IAP was not different in case of first episode or recurrence of hyperthyroidism and was not related to type or duration of medical treatment. Comparison of patients with or without IAP show higher levels of TPO- and thyroglobulin-antibodies but not of TBIAb in the former group (P < 0.005). TBIAb were higher when ophthalmopathy and/or dermopathy were present vs absent (p < 0.05) and were correlated with FT4 levels (p < 0.05). The negative predictive value of TBIAb, TPO- and thyroglobulin-antibodies to predict the lack of significant IAP was 42%, 65% and 64%. The total absence of clinical, biological and histological signs of thyroid autoimmunity was found in only one case (female aged 35 with first episode of hyperthyroidism and no family history of thyroid disease) (0.9%). These results suggest that routine available criteria of thyroid immunity (including IAP) have a low specificity. It follows that they are probably inadequate to screen cases of hereditary toxic familial hyperplasia, a rare entity of still unknown prevalence.