Endocrine Abstracts

TSH receptor antibodies (TRAB) are now routinely measured in patients with Graves’ disease (GD) to aid diagnosis. Thyroid peroxidase antibodies (TPO) sometimes co-exist in these patients but not always. Some studies have suggested a functional and prognostic role for these antibodies. However, the phenotypic characteristics of the patient with positive TPO (with or without TRAB) and the influence of TPO on the clinical course of GD are not known.

A retrospective analysis of the health records from 14 patients with diagnosed GD who had both TRAB and TPO measured were identified from an endocrine clinic in East Kent. Data was collected on demographics, family history, duration of therapy, relapse rate and the need for early use of definitive therapy. Patients were divided into TPO+ve and TPO−ve groups. Data is expressed as mean±S.D. and groups compared using un-paired t-testing. A P value of <0.05 was considered significant.

Nine patients were TPO+ve. They were predominantly female (89%) and younger (42.2±19.2 years) compared 40% and 50.0±15.8 years respectively in the TPO−ve group. A positive family history was present in 60% TPO+ve patients but in none of the TPO−ve patients. TPO+ve patients were treated for longer (17.9±2.5 vs 13.2±5.0 months, P=0.046), had 30% relapse rate within 12months of discontinuing therapy and 20% needed radioactive iodine therapy (RAI) early. None of the TPO−ve relapsed nor required RAI. TPO+ve patients had higher TRAB levels although not significantly so (17.3±16.14 vs 2.6±1.9 U/l, P=0.19).

This study has demonstrated that the presence of TPO in Graves’ disease results in a phenotype of patients with a more aggressive disease pattern that takes longer to treat, has a higher relapse rate, mainly females and younger age group compared to those patients without TPO. This finding has practical implications for the management of GD but larger studies will be required to confirm the findings.