Comparison of thyroglobulin and thyroid peroxidase antibodies

[Andyb1205]

Interesting find in the Endocrine Journal, published by Japan’s Endocrine Society.

“It has long been believed that TPOAb is superior to TgAb for detection of thyroid autoimmune abnormali- ties [2, 16]. In fact, TPOAb is recommended as the first choice of antibody measurement in the guidelines of the American Thyroid Association [17] and the American Endocrine Society [18]. This idea was introduced when measuring TGHA and MCHA was the standard; indeed, MCHA was superior to TGHA in the screening study of subclinical and mild autoimmune thyroiditis [4, 5]. When comparing MCHA and TGHA, TGHA- positive samples always showed positive MCHA [3]. MCHA antigen was a solubilized microsomal fraction obtained from Graves’ thyroid tissue [3]. This frac- tion may contain thyroglobulin antigenicity. In fact, MCHA- and TGHA-positive samples become negative for both MCHA and TGHA reactions after absorption with thyroglobulin (unpublished data). Therefore, posi- tive MCHA was possibly obtained not only by TPOAb but also by TgAb. Thus, screening using MCHA was superior to get positive reaction. After the introduction of recombinant thyroid peroxidase [8, 9], TPO immu- noassay only detects antibodies against TPO but not against thyroglobulin. In this study, it became clear that TgAb was more useful than TPOAb in Japanese patients with Hashimoto’s thyroiditis and painless thyroiditis using commercially available kits. (...)

In conclusion, TgAb prevalence was higher than that of TPOAb in Japanese patients with Hashimoto’s thyroiditis and painless thyroiditis, and TgAb is more useful than TPOAb for detection of thyroid autoimmu- nity. We suggest that the TgAb immunoassay should be the first choice of screening test for thyroid autoim- mune abnormalities in Japan.”

jstage.jst.go.jp/article/en...

It is suggested that, at least in Japan, the reason for higher sensitivity of TGab compared to TPOab is the higher dietary consumption of iodine. Given the anecdotes by thyroid patients in other countries who tested negative for TPOab but positive to TGab, suggesting Hashimotos, both antibodies should be tested together.

[Hashi-Monster]

Interesting my TGAb was high (455) a year before my Hashi diagnosis. The Australian GP at the time just said that it was high because of my coeliacs and that my thyroid was fine as my TPOab and FTs were all in range.

[Supul]

Interesting.

It was my TGAb that was high when I really suffered thyroid crises after 25 yr on levothyroxine. My GP would not entertain my belief that my thyroid was really struggling. I had to get diagnosed by a more understanding and thorough investigation by a Dr practicing in London hospital. Only then, did I get my levothyroxine dose altered twice! by my GP.

Begs the question, why aren't most GP getting to understand, patients know their body, and that research is out there, reinforcing what the actual problem is?

Thanks for sharing.