ANOMALOUS THYROTROPIN VALUES

  • 1 July 1987
    • journal article
    • research article
    • Vol. 33  (7) , 1213-1214
Abstract
We studied problems associated with use of an "ultrasensitive" thyrotropin (TSH, thyroid-stimulating hormone) assay for diagnosis of hyperthyrodism. Of 955 TSH assays performed in our laboratory during four months, 135 gave TSH values < 0.1 milli-int. unit/L. We noted low TSH values at all concentrations of free thyroxine (FT4) in plasma. Nine of 13 patients with a normal or low FT4 and no obvious endocrine explanation for a low TSH were elderly and ill. This raises questions about the pituitary function in such patients. Twenty-seven patients who had high FT4 and non-suppressed TSH were clinically euthyroid, 20 of them being on treatment with thyroxine or amiodarone. Low TSH values in a hospital environment do not always indicate hyperthyroidism, although a normal value for TSH probably indicates euthyroidism.