Endocrine Abstracts

Background: Hashimoto thyroiditis (HT) is defined as thyroid chronic inflammation due to high level antithyroperoxydase antoantibodies (ATPO) and/or antithyroglobuline autoantibodies (ATG) and their destructive process on thyroid cell. The diagnostic uses specific and very characteristic ultrasound features. What diagnosis has to have those patients with ultrasound features of HT, who are hypothyroid, but with normal levels of ATPOs and normal levels of ATGs ?

Method: i) ATPO and ATG levels were analyzed in accreditated Bucharest laboratories. ii) We considered HT those patients with high ATPO/ATG levels, cut off over 34 ui/ml. iii) FT₄ and TSH were considered for functional diagnostic. iv) Thyroid ultrasound was done with a 7.5–10 MHz probe. v) Idiopathic means: I do not know what it is, after eliminating all I know !

Results: A. Patients: 3962. B. Based on ATPO/ATG level we considered: i) HT: 1753; ii) thyroiditis with only high ATG (ATPO normal): 205; iii) Other thyroid diseases (mostly nodules): 1878 - ATPO/ATG normal, 1729 euthyroid, 113 hyperthyroid, no TRAB, 38 identified cause of induced hypothyroidism. iv) Special patients with hypothyroidism with normal ATPO and normal ATG, without any intervention on thyroid (thyroidectomy, 131-I) or neck area (radiation for lymphomas) and ultrasound features indicating inflammation: 205.

Discussion: ATPO evolution in HT is mostly undulatorious (Ratcu, this congress). In some patient, ATPO decreased under the cut off limit, if they had no thyroid, through thyroid interventions, and thyroid atrophy. These patients were hypothyroid. It is possible in evolution when the antigen (thyroid) disappeared, the autoantibodies disappeared, too ! Like in special patients described in point 4 ?

Conclusions: 1. Those patients who are hypothyroid, without a known and identifiable causes of hypothyroidism, who present obvious ultrasound sign of HT, but in who ATPO and ATG is in normal limits, have to be considered as idiopathic myxedema.