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CIRCULATING TSH LEVELS MEASURED WITH AN IMMUNOCHEMILUMINOMETRIC ASSAY IN PATIENTS TAKING DRUGS INTERFERING WITH BIOCHEMICAL THYROID STATUS
Author(s) -
EVANS P. J.,
WOODHEAD J. S.,
WEEKS I.,
SCANLON M. F.
Publication year - 1987
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.1365-2265.1987.tb00831.x
Subject(s) - euthyroid , carbamazepine , medicine , endocrinology , phenytoin , thyroid , reference range , free thyroxine , anticonvulsant , hormone , heparin , thyroid stimulating hormone , thyroid function , epilepsy , psychiatry
SUMMARY Serum TSH was measured using a high sensitivity immunochemiluminometric assay (ICMA) in patients receiving anticonvulsant drugs, heparin or nonsteroidal anti‐inflammatory agents (NSAIs) and the results compared with those from groups of age‐ and sex‐matched controls. The TSH results have also been compared with those of estimates of free thyroid hormone levels using Amerlex analogue method reagents. All patients were clinically euthyroid and TSH concentrations were in the normal, euthyroid range and did not differ significantly in any group studied. In contrast, Amerlex free T4 levels were significantly reduced in the patients treated with phenytoin ( P < 0001), carbamazepine ( P < 001), sodium valproate ( P < 001) and heparin ( P < 0001). Patients treated with NSAI agents showed no significant change in free T4 levels. Amerlex free T3 levels were also significantly reduced in the patients treated with phenytoin ( P < 0–005), carbamazepine ( P < 0–005) and heparin ( P < 0–001) but not in those treated with sodium valproate or NSAIs. These data support the view that measurement of circulating TSH with an assay of sufficient precision in the relevant range provides a reliable way of assessing thyroid status and could be used to exclude hyperthyroidism in patients taking the medications investigated in this study.