Thyrotropin-receptor antibodies in
patients with hyperthyroidism caused by Graves' disease inhibit
thyrotropin secretion
(March 2002)
The background of the study. Patients
who have hyperthyroidism have low serum thyrotropin (TSH) concentrations.
When the patients are treated, serum TSH concentrations rise to
normal or above. In some patients the recovery of TSH secretion
is delayed. This study was done to determine if the TSH receptor-stimulating
antibodies present in the serum of patients with hyperthyroidism
caused by Graves' disease inhibit TSH secretion.
How the study was done. The effect
of TSH receptor-stimulating antibodies on TSH secretion was studied
in rats. The rats were given immunoglobulins (IgG) purified from
the serum of a normal subject and patients with hyperthyroidism
caused by Graves' disease; the latter had high serum concentrations
of TSH receptor-stimulating antibodies. Blood samples were collected
for measurement of plasma TSH 1, 2, 4, 8, 24, and 48 hours after
the injections.
The results of the study. After
the injections of IgG, the 48-hour mean plasma TSH concentration
in the rats that received the IgG prepared from the serum of patients
with hyperthyroidism was lower than in the rats that received the
normal IgG.
The conclusions of the study. In
patients with hyperthyroidism caused by Graves' disease, TSH secretion
may be inhibited not only by the high serum T4 concentrations, but
also by TSH receptor-stimulating antibodies.
The original article. Brokken LJS,
Scheenhart JWC, Wiersinga WM, Prummel MF. Suppression of serum TSH
by Graves' Ig: evidence for a functional pituitary receptor. J Clin
Endocrinol Metab 2001;86:4814-7.
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