Hyperprolactinaemia in Pregnancy

Hyperprolactinaemia in pregnancy is raised prolactin from a known prolactinoma, drugs or other causes, in a woman who is pregnant or planning pregnancy. Prolactin rises 10 times in normal pregnancy, so levels are not used for monitoring. It matters because pituitary tumours can enlarge in pregnancy under oestrogen, causing headache and visual loss, and dopamine agonists must be adjusted.

• Microprolactinoma rarely enlarges in pregnancy.
• Macroprolactinoma enlarges more often and needs visual field checks.
• Most women conceive after treatment restores ovulation.

Women have a known prolactinoma on treatment, or earlier amenorrhoea, galactorrhoea and infertility before conception. In pregnancy the warning symptoms are new headache and visual field loss.

• Headaches that are new or severe.
• Bitemporal hemianopia suggests chiasm compression.
• Differential diagnosis: physiological pregnancy prolactin rise, drug induced hyperprolactinaemia, nonfunctioning adenoma, acromegaly, hypothyroidism, pituitary apoplexy.
• Complications: tumour enlargement, visual loss, pituitary apoplexy, hypopituitarism, diabetes insipidus, loss of lactation after delivery.

The approach is clinical review and visual assessment, not repeated prolactin.

• Visual fields by confrontation or perimetry each trimester for macroadenoma, and at once for headache or visual change.
• MRI of the pituitary without gadolinium for visual symptoms or severe headache.
• Prolactin levels are not useful because they rise during pregnancy.
• TSH, free T4, morning cortisol and sodium if hypopituitarism is suspected.

The principle is to stop the dopamine agonist for microadenoma and continue or restart it for macroadenoma or symptomatic growth.

• Supportive: preconception counselling; barrier contraception until the first menstruation after treatment; avoid breast stimulation; headache and vision warning advice.
• Pharmacological: microprolactinoma: stop cabergoline or bromocriptine once pregnancy is confirmed; macroprolactinoma: continue bromocriptine 2.5 mg oral 8-hourly (maximum 15 mg daily), started at 1.25 mg at night and increased every 3 to 7 days; for tumour growth with headache or visual change restart bromocriptine 2.5 mg oral 8-hourly or cabergoline 0.25 to 0.5 mg oral twice weekly; paracetamol 1 g oral 6-hourly as needed (maximum 4 g in 24 hours); hydrocortisone 100 mg IV 8-hourly for apoplexy; for hypopituitarism give hydrocortisone 10 mg oral on waking and 5 mg oral in the afternoon.
• Procedures: trans-sphenoidal surgery in the second trimester for visual loss that fails to respond to a dopamine agonist.
• Special groups: after delivery breastfeeding is allowed, and macroprolactinoma women restart the dopamine agonist only if they are not breastfeeding or if tumour symptoms recur; women with hypopituitarism give hydrocortisone 100 mg IV in labour then 50 mg 6-hourly for 24 hours.
• Red flags: sudden severe headache, vomiting, visual loss, diplopia, collapse, hypotension.
• Follow-up: visual fields each trimester for macroadenoma; clinical review monthly; MRI 6 to 12 weeks postpartum; prolactin and symptoms after weaning.