Endocrine Abstracts

A 33-year-old woman who was 38-weeks pregnant was referred to our Endocrine team for bilateral temporal hemianopia. Her past medical history includes juvenile myoclonic epilepsy, for which she takes lamotrigine 275mg BD. She was reviewed by the Endocrinologist in 2018 for polyuria and nocturia which were attributed to the introduction of antiepileptics (normal pituitary biochemistry and MR pituitary). Her symptoms subsequently improved. Current symptoms started with acute retroorbital headache followed by blurring of her peripheral vision. Her headaches improved with hydration but her visual symptoms persisted. She did not reveal any symptoms related to anterior pituitary hormone abnormalities. She reports nocturia (3 times overnight) since the beginning of third trimester however, no polydipsia. Clinical examination showed bitemporal hemianopia. Fundoscopy showed normal optic discs. Pituitary blood tests:

ACTH: 9 ng/l, cortisol: 70 nmol/l (at 3.50 pm)

IGF-1: 162 microgram/l

fT4: 5.6 pmol/l, TSH: 1.19 mU/l

Prolactin: 1,754 mU/l

Urine osmolality: 365 mmol/kg, serum osmolality: 277 mmol/kg, serum sodium: 135 mmol/l.

An urgent MR brain and pituitary showed significant enlargement of her pituitary gland, and an upwards extension and compression of the optic chiasm. Neuro-ophthalmology assessment revealed bilateral enlarged blind spots with an early bitemporal hemianopia with marginally reduced visual acuity in the right eye and slight reduction in colour vision in both eyes. Retinal OCT findings were unremarkable. The working diagnosis was a non-functioning pituitary macroadenoma or lymphocytic hypophysitis. We commenced dexamethasone 6mg OD and bromocriptine 2.5mg OD to reduce the size of the lesion. Levothyroxine 50 mg was also started. Repeat neuro-ophthalmology assessment after 48 hours revealed no improvement. As such, she had an emergency c-section (baby safely delivered) to enable us to plan for urgent surgical decompression. Bromocriptine was stopped at this point. A repeat MR pituitary with contrast post-delivery did not reveal any improvement and her visual symptoms persisted. Her dexamethasone was stopped after 5 days, and she was commenced on hydrocortisone (10 mg/5 mg/5 mg). She was referred for urgent transsphenoidal surgery. The appearances of the pituitary were in keeping with hypophysitis so only biopsy was taken. Her hydrocortisone was changed to prednisolone 30 mg. Her biopsy results confirmed lymphocytic hypophysitis. Since starting prednisolone, she has developed diabetes insipidus. Her vision improved, and her visual fields are normal to red pin confrontation. Central scotoma has also normalised. This case demonstrates the diagnostic challenges of lymphocytic hypophysitis in pregnancy and the importance of early diagnosis and management. Early initiation of high-dose steroids could result in favourable neuro-ophthalmic outcome.