Download TSH Receptor Antibodies (TRAb) (serum)

TSH Receptor Antibodies (TRAb) (serum)
Description
TSH receptor antibodies (TRAb) are autoantibodies
directed against the TSH receptor. TSH receptors are
located predominantly on thyroid epithelial cells surfaces.
Indication
TRAb measurement is particularly useful in the assessment
of pregnant women with a past or current history of Graves’
disease, to determine the likely risk of foetal/neonatal
thyrotoxicosis.
Measurement can also be useful in distinguishing between
postpartum thyroiditis and Graves’ disease and in the
investigation of hyperthyroidism of uncertain aetiology,
investigation of patients with suspected ‘euthyroid Graves’
ophthalmology’ and to identify neonates with transient
hypothyroidism due to TSH blocking antibodies.
Additional Info
Two types of TRAb may be associated with autoimmune
thyroid disorders. Thyroid-stimulating autoantibodies
stimulate thyroid cells, acting in place of TSH and causing
the production of excess thyroid hormone and are
associated with Graves’ hyperthyroidism. TRAb may also
be blocking or binding. Blocking antibodies block the action
of TSH on thyroid cells; binding antibodies bind to the TSH
receptor and prevent TSH and other TSH receptor
antibodies from reacting with the TSH receptor. These
antibodies are associated Hashimoto’s thyroiditis
(hypothyroidism). Therefore, although TRAb are most
commonly linked with Graves’ Disease, they may also be
present in hypothyroidism.
Concurrent Tests
TSH, FT4, FT3
Dietary Requirements
N/A.
TRAb results can be interpreted as follows:
Negative:
≤ 1.7 IU/L
Positive:
> 1.7 IU/L
Interpretation
It is useful as a confirmatory test and following treatment.
In pregnancy TRAb cross the placenta and affect the foetal
thyroid.
The demonstration of positive TRAb during
pregnancy will alert the obstetrician to possible problems with
the baby in the neonatal period.
Collection Conditions
N/A
Frequency of testing
N/A
Version 2.0
Document agreed by: Dr V Mishra
Date: 29/07/15