ISOLATED TSH DEFICIENCY WITH A PARTIALLY EMPTY SELLA

Isolated TSH deficiency is rare. The diagnosis is based on (i) symptom s and signs of thyroid hormone deficiency, (ii) demonstration of an ab sent or impaired TSH response to TRH and (iii) other pituitary hormone s remaining intact. We report a 60-year-old female in whom isolated TS H deficiency was found, with a free thyroxine - 7.0 pmol/L (11 - 20), total triiodothyronine level -1.5 nmol/L (1.1 - 2.6) and thyroid stimu lating hormone - 0.87 mU/L (0.38 - 4.3). A TRH test on two separate oc casions demonstrated an inappropriately low TSH response. Computed ass isted tomography revealed a partially empty sella and other pituitary hormones were demonstrated to be intact. We were unable to detect pitu itary antibodies using indirect immunofluorescence on sections of monk ey pituitary, Treatment with thyroxine improved this patient's symptom s and suppressed the TSH further.