Pituitary Adenoma in Pregnancy

Pituitary adenoma in pregnancy is a benign tumour of the pituitary gland, in a woman who is pregnant or pregnant after treatment. Types include prolactinoma, nonfunctioning adenoma, growth hormone secreting adenoma (acromegaly) and ACTH secreting adenoma (Cushing disease). The normal pituitary enlarges in pregnancy, and tumours can swell. It matters because macroadenomas may cause headache, visual loss and apoplexy, and hormone excess affects pregnancy outcome.

• Macroadenoma (above 10 mm) is more likely to enlarge in pregnancy.
• Microadenoma (below 10 mm) rarely enlarges.
• Hypopituitarism needs hormone replacement and adjustment.

Women are usually asymptomatic or have known disease, with new headache and visual field defects when tumours enlarge. Acromegaly causes coarse features, hypertension and glucose intolerance; Cushing disease causes hypertension and diabetes.

• Headache and bitemporal hemianopia.
• Sudden severe headache with vomiting and collapse suggests apoplexy.
• Differential diagnosis: physiological pituitary enlargement, preeclampsia headache, migraine, lymphocytic hypophysitis, meningioma, craniopharyngioma, venous sinus thrombosis.
• Complications: visual loss, apoplexy, hypopituitarism, diabetes insipidus, gestational diabetes, preeclampsia, postpartum haemorrhage with Sheehan syndrome.

The approach is visual assessment, MRI for symptoms and hormone tests by type.

• Visual fields by perimetry or confrontation each trimester for macroadenoma; urgently if symptoms appear.
• MRI of the pituitary without gadolinium for headache or visual change.
• TSH, free T4, 9 am cortisol, sodium, glucose; prolactin and IGF-1 are not useful because they change in pregnancy.
• 75 g oral glucose tolerance test at 24 to 28 weeks in acromegaly or Cushing disease.

The principle is surveillance, medical treatment for growth, replacement of deficient hormones and surgery for failing visual loss.

• Supportive: preconception counselling; headache and vision warning advice; avoid further exogenous oestrogen; delivery in a facility with neurosurgical access.
• Pharmacological: bromocriptine 2.5 mg oral 8-hourly (maximum 15 mg daily) or cabergoline 0.25 to 0.5 mg oral twice weekly for prolactinoma with enlargement; hydrocortisone replacement 10 mg oral on waking and 5 mg oral in the afternoon for adrenal insufficiency, doubled for illness; levothyroxine 1.6 micrograms/kg oral daily, titrated to free T4 in the upper half of normal; desmopressin 0.1 to 0.2 mg oral every 8 to 12 hours for diabetes insipidus, adjusted to serum sodium 135 to 145 mmol/L; hydrocortisone 100 mg IV 8-hourly for suspected apoplexy; in labour give hydrocortisone 100 mg IV then 50 mg 6-hourly for 24 hours, then reduce to maintenance over 3 days.
• Procedures: trans-sphenoidal surgery in the second trimester for progressive visual loss that fails medical treatment; vaginal delivery is usual unless there are neurological reasons for caesarean section.
• Special groups: women with acromegaly or Cushing disease need glucose and blood pressure control with insulin or methyldopa 250 to 500 mg oral 8-hourly (maximum 3 g daily); breastfeeding is allowed unless dopamine agonists are needed for tumour growth.
• Red flags: sudden severe headache, vomiting, visual loss, ophthalmoplegia, collapse, hypotension, hyponatraemia, polyuria.
• Follow-up: visual fields each trimester for macroadenoma; clinical review monthly; MRI at 6 to 12 weeks postpartum; pituitary hormone testing and endocrine review at 3 months.