Case History/Examination:
A 37-year-old male presented to the clinic with palpitations, weight
loss, and easy fatigability. On examination, he appeared thin, with a
BMI of 19 kg/m², and exhibited resting tachycardia with a regular pulse
of 104 bpm. He had tremors in his outstretched hands and bilateral neck
swelling with an audible thyroid bruit. There were no eye signs of
hyperthyroidism or evidence of pretibial myxedema. He had been treated
for thyrotoxicosis over the past seven years outside the hospital,
receiving anti-thyroid medications and radioactive iodine (RAI) therapy.
After RAI, he was started on levothyroxine. Despite gradually increasing
the levothyroxine to the maximum dose, his TSH levels remained elevated,
and symptoms of hyperthyroidism persisted. Initial workup showed a TSH
of 48 µIU/mL (normal range: 0.35–5.5 µIU/mL), FT4 of 4.8 ng/dL (normal
range for adults >20 years: 0.89–1.76 ng/dL), and FT3
exceeding 20 pg/mL (normal range: 2.4–4.2 pg/mL). The elevated FT4 and
FT3 levels, alongside non-suppressed TSH, suggested a central cause of
hyperthyroidism. The rest of the pituitary hormones were in the normal
range except for raised testosterone with inappropriately average values
of LH and FSH (Table 7)
Brain MRI revealed a 9 x 12 mm mass in the sellar region