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Lalani et al., Bronx, NY, USA, studied the prevalence of autoimmune
thyroid disease in 653 patients with diabetes type II. 18.8% of patients
had autoimmune thyroid disease (105 autoimmune hypothyroidism and 18 a
history of Graves' disease). Of this group, age of onset of diabetes was
between 23-73 years, 27% were males, 80% were obese, 60% had a family history
of diabetes, and 48% ultimately needed insulin. The authors conclude that
all patients with type II diabetes should be screened for autoimmune thyroid
disease. (Comment: It is a great disadvantage that no control population
was studied so that it is not known whether the prevalence of autoimmune
thyroid disease in this patient group is different from the general population.)
DiConstanzo et al., Marseille, France, and Berlin, Germany, studied the prevalence of so-called bispecific TGPO autoantibodies (aAb), i.e. antibodies that recognized both TG and TPO, in different patients groups: Hashimoto's thyroiditis (n = 439) positive in 40.3%, Graves' disease (n = 647) 34.5%, thyroiditis with unknown origin (n = 44) 29.5%, toxic multinodular goiter (n = 115) 6.1%, euthyroid multinodular goiter (n = 61) 4.9%, uninodular goiter (n = 67) 3.0%. Prevalence was 0% in toxic nodule (n = 47), De Quervain (n = 19) and Riedel's thyroiditis (n = 75). In other autoimmune diseases like pernicious anaemia, insulin dependent diabetes, SLE, or vitiligo, prevalence varied between 2.7 and 10.3%. These results show that the prevalence of TGPOAb is much higher in thyroid autoimmune disease than in non-thyroid autoimmune diseases. (Comment: Further studies are necessary to assess the specific significance of this type of antibody in the characterization of thyroid autoimmune disorders.) Takamatsu et al., Osaka, Kobe and Mibucho, Japan, studied characteristics of three groups of patients with Hashimoto's disease, i.e. having both TGAb and TPOAb, TGAb alone, or TPOAb alone. Of 401 patients with Hashimoto's thyroiditis 79% had both antibodies, 19% TGAb alone, and 2% TPOAb alone. Age, gender-ratio, and incidence of familiar predisposition were similar in the three groups. The main findings were that patients with TGAb alone have frequently nodular lesions i.e. 53% versus 20% TPOAb alone, and 9% both antibodies. In this group hypothyroidism was relatively rare i.e. 23% versus 50% and 58% respectively. The frequences of low echo-amplitude of the thyroid were 26%, 0%, and 69% respectively. Lee et al., Chicago, IL, USA, previously reported that oral tolerization with thyroglobulin suppressed experimental autoimmune disease in mice. They now tested this hypothesis in humans. Thirteen patients on thyroid hormone replacement with synthetic T4 (5 patients with Graves' disease treated with radioactive iodine in the past and 8 patients with Hashimoto's thyroiditis) were randomized to a test group that switched to replacement with desiccated thyroid from porcine thyroids, and a control group maintaining on synthetic T4. The ultimate findings were that the patients who were switched to desiccated thyroid showed no changes in humoral immunity parameters, while cellular immunity to certain peptides was apparently suppressed. The authors rightly conclude that more evidence is needed before it is justified to treat humans with autoimmune thyroiditis with autoantigens. (Comment: This report is very interesting and extends the findings of these authors from the experimental animal to the human. Further studies are anxiously awaited.) Smyth et al., Dublin, Ireland, investigated the prognostic significance of the presence of TPO antibodies in the outcome of breast cancer. They found positive antibodies in 156/380 (41%) of breast cancer patients versus 34/200 (17.0%) of age matched female controls. The presence of TPO antibodies was associated with improved outcome following therapy of breast cancer only if thyroid volume varied between 9.4 and 18.8 ml. At 5 years disease free survival was 65% compared to 36% in TPO negative breast cancer patients after therapy. For the same period overall survival was 93 and 54% respectively. (Comment: The mechanistic and clinical significance of these findings is not known and the question is if selection bias, i.e. on the basis of thyroid volume, are involved.) The same group reported a study of TPO measurements in homogenates prepared from normal breast (n = 2), benign fibroadenomata (n = 24), and in patients with breast cancer, in cancer tissue and in morphologically normal tissues from the same tumor-bearing breast (n = 17). The results were that a nonsignificantly increased TPO content was found both in benign and in malignant breast epithelial tissue as compared to normal breast epithelium. Remote breast epithelial from the same breast that harboured benign or malignant tissue, contained similar TPO levels as epithelial breast tissue from normals. (Comment: The biological significance of TPO in breast tissue and its possibly elevated concentration in breast tumors is completely unknown. These results are of interest with regard to the question if TPO plays a role in the generation of breast tumors.) |
