[Methodical evaluation of immunoluminometric determination of thyroid peroxidase in serum]

With the identification of thyroid peroxidase (TPO) as the specific autoantigen in autoimmune diseases of the thyroid, the development of a commercial assay for detection of TPO in human serum became possible. The diagnostic value of this TPO assay was evaluated in 194 patients with various thyroidal diseases. The assay appeared to be easily affected by specific and/or unspecific interferences such as TPO-auto-antibodies in the patient's blood samples. To analyze these effectors every sample was checked in a parallel recovery test. In most of the cases with elevated anti-TPO levels an exact determination of TPO could not be estimated correctly. Whenever a correct measurement of TPO was possible, to none of the different examined groups of thyroid diseases a correlation of TPO-levels could be demonstrated. Moreover, the value of TPO determination as a tool in the follow-up of differentiated thyroid carcinoma was not provable. For the time being our studies do not suggest TPO measurements being helpful in thyroidal diagnosis.