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Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model
Published on: March 17, 2023
Performance of a third-generation TSH-receptor antibody in a UK clinic
A Theodoraki1, G Jones, J Parker
1Departments of EndocrinologyClinical ImmunologyClinical Biochemistry, Royal Free Hampstead NHS Trust, London, UK.
Background:
UK national guidelines recommend the measurement of TSH receptor antibodies (TRAb) in certain clinical scenarios. A commercial third-generation TRAb autoantibody M22-biotin ELISA assay was introduced in May 2008 in our centre.
Objective:
To evaluate the diagnostic performance of a TRAb assay in a retrospective and subsequently a prospective cohort in a UK centre.
Design:
A retrospective review of patients with thyroid disease followed by a prospective observational study in consecutive patients with newly found suppressed serum thyrotrophin (TSH).
Patients And Measurements:
Medical records of 200 consecutive patients with thyroid disorders who had TRAb measured since the introduction of the assay. In a prospective study 44 patients with newly identified hyperthyroidism (TSH < 0·02 mIU/l) had sera assayed for TRAb prior to their clinic appointment at which a final diagnosis was sought.
Results:
In the retrospective cohort, the manufacturer's cut-off point of TRAb ≥0·4 U/l resulted in a positive predictive value (PPV) of 95%, sensitivity 85%, specificity 94% and negative predictive value (NVP) 79% to diagnose Graves' disease using defined criteria. Receiver operating characteristic (ROC) analysis determined an optimal cut-off point of TRAb ≥3·5 U/l with a 100% specificity to exclude patients without Graves' disease at the cost though of a lower sensitivity (43%). In the prospective study, the sensitivity, PPV, specificity and NPV were all 96% using the ≥0·4 U/l cut-off. When combining hyperthyroid patients from both cohorts the assay sensitivity and specificity at ≥0·4 U/l cut-off were 95% and 92% respectively. A positive TRAb result increased the probability of Graves' disease for a particular patient by 25-35% and only six (2·5%) patients had a diagnosis of hyperthyroidism of uncertain aetiology after TRAb testing.
Conclusions:
The assay studied specifically identifies patients with Graves' disease. It is a reliable tool in the initial clinical assessment to determine the aetiology of hyperthyroidism and has the potential for cost-savings.
