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RESTORATION OF NORMAL THYROTROPHIN SECRETION REDUCES THE ABNORMALLY HIGH SERUM GLUTATHIONE S‐TRANSFERASE LEVELS FOUND IN PATIENTS RECEIVING THYROXINE REPLACEMENT THERAPY
Author(s) -
GOW S. M.,
CALDWELL G.,
TOFT A. D.,
SWEETING V. M.,
BECKETT G. J.
Publication year - 1988
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1988.tb01222.x
Subject(s) - endocrinology , medicine , secretion , glutathione s transferase , glutathione , chemistry , enzyme , biochemistry
SUMMARY The peripheral tissue thyroid status of 12 patients receiving thyroxine replacement therapy was investigated both when pituitary secretion of TSH was suppressed and later, when on a lower dose of thyroxine that restored thyrotroph responsiveness. Heart rate and various analytes in serum known to be sensitive to thyroid status were measured in addition to TSH by immunoradiometric assay. Initially, the serum T4 concentration was raised in seven patients and free T 4 raised in nine; all patients had normal T 3 concentrations. Later, on the lower dose of thyroxine, most patients had concentrations of thyroid hormones within reference limits. Concentrations of the liver‐specific form of glutathione S‐transferase (GST) in serum decreased (P< 001) after the reduction in thyroxine dose; abnormally high GST levels, found in eight patients when TSH was suppressed, returned to normal in six of these patients when normal basal and TRH‐stimulated TSH concentrations had been restored. The response of the pituitary to excess thyroxine may be more representative of other tissues (e.g. the liver) than previously thought.