Endocrine Abstracts

Case history: A 68 year old woman was referred to Endocrinology with a history of vomiting, extreme fatigue of acute onset and non-specific visual changes. She had a history of primary hypothyroidism and an adenocarcinoma of the lung with bone metastases initially been treated with pemetrexed and cisplatin chemotherapy. The patient subsequently required palliative radiotherapy for metastatic spinal cord compression and was started on denosumab. Imaging shortly before her referral to Endocrinology was suggestive of local disease recurrence for which palliative radiotherapy was arranged.

Investigations: Initial investigations by the Oncology team revealed a 0900 h cortisol of 108 nmol/l, FT4 11.5 pmol/l and TSH 0.11 miu/l. A full pituitary screen and MRI of the brain were subsequently performed.

Results and treatment: Following the initial investigations the patient was commenced on hydrocortisone 20 mg on waking and 10 mg in the early evening. Her levothyroxine was increased from 50 μg to 75 μg daily. The results of a full pituitary profile were as follows: FT4 14.9 pmol/l, FT3 3.4 pmol/l, TSH 0.05 miu/l, FSH 2.8 u/l, LH <0.1 u/l, prolactin 3786 mu/l (84% macroprolactin recovery), oestradiol <92 pmol/l, testoterone <0.5 nmol/l, cortisol 321 nmol/l, IGF 1 85 ng/ml. An MRI brain revealed a lobulated sellar and suprasellar lesion with oedema of the optic chiasm. Visual field testing revealed a bitemporal hemianopia.The case was reviewed in a pituitary MDT and the imaging felt to be consistent with pituitary metastases. Treatment with hydrocortisone, monitoring for diabetes insipidus and consideration of radiotherapy was recommended. The patient subsequently reported polyuria and polydipsia. Investigations were consistent with diabetes insipidus and treatment with desmopressin was commenced.

Conclusions and points for discussion: This patient’s hypopituitarism and hyperprolactinaemia were attributed to pituitary metastases. The hyperprolactinaemia was felt to result from stalk compression rather than a pituitary tumour. Pituitary metastases are rare but most commonly associated with malignancies of the breast and lung. Their presentation can relate to mass effect and/or hormonal dysfunction. The symptoms of hypopituitarism can mimic those associated with malignancy and oncological treatments. Certain monoclonal antibodies carry a risk of hypophysitis of auto-immune aetiology. Regular monitoring of pituitary function could be considered in at risk patients and symptoms of hypopituitarism should be promptly investigated. Identification of the likely cause of hypopituitarism will guide management. In the case of pituitary metastases, whole brain radiotherapy and surgical decompression can be considered.