Endocrine Abstracts

A 51 year old woman was referred for investigation of goitre. The patient described weight loss, sweating and hot flushes for 3 years. A bilateral salpingo-oophorectomy had been performed 14 years prior to presentation but the patient had been off HRT for 12 years.

On examination the patient was thin, nervous and sweaty with a sinus tachycardia and a smooth goitre, but no signs of thyroid eye disease.

Thyroid hormone levels were elevated, fT4 33 pmol per litre, fT3 9.7 pmol per litre. However, TSH was not suppressed, 27.44 IU per litre. MRI revealed a pituitary macroadenoma infiltrating the left cavernous sinus and compressing the optic chiasm. Thyroid autoantibodies were positive, thyroglobulin 3966, TPO 1296. A technetium thyroid scan showed slight and generalised increased uptake. Further endocrine tests revealed low gonadotropins LH 0.5; FSH 1.1 U per litre, prolactin 406, 9am Cortisol 360 nmol per litre, GH 1.2 mU per litre, IGF-1 15 nmol per litre

Sandostatin LAR 30mg im was initiated. TSH fell from 26.56 to 2.21 IU per litre within 2 days and remained normal at weekly follow-up 1.78, 3.09, 2.83 IU per litre respectively. Prior to the fourth dose, the patient became hypothyroid, and thyroid replacement therapy was initiated.

Tumour shrinkage was noted after 1 month, but there was no further shrinkage after 6 months of treatment. The patient has now accepted neurosurgical assessment.

Thyrotropin secreting pituitary adenomas are rare, but should be considered in patients with an inappropriately elevated TSH. We present the case of a woman with a macroadenoma with good response to inhibitory hormonal control. The development of hypothyroidism was unexpected. However, the patient was managed medically with a 'block-replace' regimen which successfully normalised thyroid biochemistry and controlled symptoms.