Non-Conventional Clinical Uses of TSH Receptor Antibodies: The Case of Chronic Autoimmune Thyroiditis

Abstract

Anti TSH receptor antibodies (TSHrAb) are a family of antibodies with different activity, some of them stimulating thyroid function (TSAb), others with blocking properties (TBAb), it is a common finding that antibodies with different function might coexist in the same patient and can modulate the function of the thyroid. However, most of the labs routinely detect all antibodies binding to the TSH receptor (TRAb, i.e. TSH-receptor antibodies detected by binding assay without definition of functional property). Classical use of TSHr-Ab assay is in Graves’ disease where they are tested for diagnostic and prognostic issues; however, they can be used in specific settings of chronic autoimmune thyroiditis (CAT) as well. Aim of the present paper is to highlight these conditions where detection of TSHr-Ab can be of clinical relevance. Prevalence of TSHrAb is different in in the 2 main form of CAT, i.e. classical Hashimoto’s thyroiditis and in atrophic thyroiditis, where TBAb play a major role. Simultaneous presence of both TSAb and TBAb in the serum of the same patient might have clinical implication and cause the shift from hyperthyroidism to hypothyroidism and vice versa. Evaluation of TRAb is recommended in case of patients with Thyroid Associated Orbitopathy not associated with hyperthyroidism. At present, however, the most relevant recommendation for the use of TRAb assay is in patients with CAT secondary to a known agent; in particular, after treatment with alemtuzumab for multiple sclerosis. In conclusion, the routine use of anti-TSH receptor antibodies (either TRAb or TSAb/TBAb) assay cannot be suggested at the present for diagnosis/follow up of patients affected by CAT; there are, however, several conditions where their detection can be clinically relevant.

Vitamin D Status in Sample of Iraqi Women with Autoimmune Thyroiditis

“…Anti-TSHR may also be found in patients with HT in whom they may contribute to the hypothyroidism of the disease. As some TSHR-Ab have a blocking effect, they may contribute to hypothyroidism 22 , or be associated with a fluctuating course between hyper and hypothyroidism 23 . The explanation behind these results is that dynamic thyroid antibody changes may be related to incident abnormal TSH levels 4 .…”

Molecular Mechanisms in Autoimmune Thyroid Disease

“…TBAbs increase the risk of hypothyroidism and are detectable in between 10 and 90% of individuals with HT, although they can also be found in a minority of GBD patients. TRAbs have also been detected that can bind to the TSHR but do not alter thyroid function; thus, these TRAbs are neutral (TNAbs) [ 312 , 313 , 314 ].…”

The Mysterious Universe of the TSH Receptor

“…However, TSHRAbs can be identified in 6,3-12% of HT patients and in 12-59% of atrophic thyroiditis patients. As some TSHRAbs have a blocking effect, they may contribute to hypothyroidism ( 5 ), or be associated with a fluctuating course between hyper and hypothyroidism ( 62 ).…”