Antibodies to thyroid peroxidase (TPOAb) in serum from patients with slightly raised thyrotropin (TSH) levels.

Assessment of thyroid antibody status can influence the decision to commence thyroxine replacement in patients with persistent marginally raised TSH concentrations. We studied 211 patients in whom we had reported a slightly raised TSH on two or more occasions. The most recent result was accompanied by a suggestion to repeat the TSH estimation and request thyroid antibodies. Although we received follow-up specimens on 59% of the audit sample, antibodies were requested on only 37%. However, a majority (62%) of those specimens showed a raised antibody concentration and this appeared to influence the decision to start thyroxine replacement. Our data suggest that it would be more effective if laboratory staff were to request thyroid antibodies on specimens from patients with persistently raised TSH concentrations and to comment further on the significance of the result.