Endocrine Abstracts

The debate on the utility of TSH receptor (TSH-R) measurement in the management of Graves’ patients has a long history (see for instance J Clin Endocrinol Metab 1998; 83: 3777–3785), and despite advances in assay techniques, the use of TSH-R antibodies in clinical practice is determined more by local custom and practice than evidence base. The diagnosis of Graves’ disease itself is usually straightforward and surrogates for TSH-R antibody testing, such as thyroid peroxidase (TPO) antibody measurement or thyroid scintiscanning, can often be used more readily than TSH-R antibodies. TSH-R antibody levels do not predict outcome after treatment sufficiently well for clinical practice. The second clinical situation in which a role for testing these antibodies has been proposed is in the diagnosis of thyroid-associated ophthalmopathy, but once again modern imaging methods and TPO antibody measurement are almost always adequate in this setting. The only established and undisputed indication remains the assessment of pregnant women who have Graves’ disease, in order to determine the likely risk of neonatal thyrotoxicosis. A publication from the European Thyroid Association (Eur J Endocrinol 1998; 139: 584–586) has laid down clear guidelines for the type of testing and timing that seems best.

The type of TSH-R antibody assay used depends on local availability, but second generation thyroid binding inhibiting immunoglobulin (TBII) assays have a very high sensitivity and specificity, especially when the results of simultaneous biochemical thyroid function tests are taken into account. Functional assays remain the gold standard for research and in rare patients in whom there is an unusual clinical picture, but wider adoption of the TBII method seems the most likely future development, as prices become more reasonable, and perhaps this can be developed into a solid phase assay that will be able to distinguish between stimulating and blocking antibodies (although the recent realisation that these 2 sets of antibodies share an overlapping epitope may slow progress in this regard).