From Monday 5th October 2026, the Clinical Biochemistry and Immunology service will be changing the method used for the Anti-Thyroid Peroxidase (Anti-TPO) test. This test is used in the assessment of subclinical hyperthyroidism and in the investigation of thyroid dysfunction.

There are no changes in sample requirements but the new cut-off for positivity is 20 IU (compared to 34 IU for the previous assay). This change is due to the department's supplier (Roche Diagnostic) moving to a new generation of assay which has reduced analytical interference. The assay targets different epitopes so the values are not directly comparable, but there is good agreement between positive and negative results between the two methods.

For further information please feel free to contact the department: peh-tr.chemimm@nhs.net.