A 41-year-old woman presented to her optician 3 weeks post-partum with frontal headaches and visual blurring. On examination, a bitemporal hemianopia was found.
She had previously been under our care with autoimmune hypothyroidism diagnosed 3 years earlier on the basis of symptoms and confirmatory biochemistry TSH 10.9 mU/l, T4 10.6 pmol/l, TPO 66 (<50). This had been adequately replaced throughout pregnancy, which had been uneventful until the final 10 days when she developed vague headaches, lethargy and dizziness. The delivery itself was uneventful.
At urgent review, her headaches, dizziness and lethargy as well as her visual field abnormalities had improved. Tests in outpatients revealed normal electrolytes and gonadotrophins. She had been unable to breast feed and her prolactin was inappropriately low (441 mU/l). Response to synacthen was sub-optimal (peak cortisol 544 nmol/l). An urgent MRI of the pituitary revealed a diffusely enlarged gland touching both cavernous sinuses and impinging on the optic chiasm. The stalk itself appeared normal.
Given the clinical context, a diagnosis of probable lymphocytic hypophysitis was made and she was commenced on hydrocortisone. Subsequent dynamic pituitary function testing revealed deficient gonadotrophin (peak LH 5, FSH 12 IU/l), GH (peak GH 5.7 mU/l) and ACTH responses (peak cortisol 102 nmol/l at 90 min). She was commenced on oestrogen replacement in addition to her hydrocortisone and her levothyroxine dose adjusted to 100 mcgs/day. Serial MRI scans showed shrinkage of the pituitary gland to below normal size over the subsequent 6 months and formal visual perimetry demonstrated a return to normal visual fields. She remains well and desires further pregnancies.
This case illustrates the need to be alert to other pathologies in the peri-partum period and the importance of the clinical context in making the correct diagnosis.