Pituitary Disorders in Pregnancy

Physiological Pituitary Changes in Pregnancy - Glandular Glow-Up

• Pituitary gland enlarges significantly (up to 135% or 2x size).
  • Mainly due to estrogen-driven lactotroph hyperplasia.
• ↑ Prolactin (PRL): Rises progressively for lactation.
• ↓ FSH & LH: Suppressed by placental steroids, preventing ovulation.
• ↑ ACTH & MSH: Leads to ↑ cortisol & skin pigmentation.
• TSH: Transient ↓ 1st trimester (hCG effect), then normal.

⭐ Pituitary gland nearly doubles in size due to estrogen-driven lactotroph hyperplasia, increasing vulnerability to Sheehan's syndrome post-hemorrhage.

Prolactinoma and Pregnancy - Milky Matters

Most common pituitary tumor; secretes prolactin (PRL). Pregnancy (↑estrogen) may enlarge tumor by stimulating lactotrophs.

• Microadenomas (<10 mm):
  • Low risk of symptomatic enlargement.
  • Stop dopamine agonists (DA) (e.g., Bromocriptine) upon pregnancy confirmation.
  • Monitor symptoms (headache, visual changes); restart DA if tumor growth/symptoms.
• Macroadenomas (>10 mm):
  • Higher risk of symptomatic enlargement.
  • Continue DA (Bromocriptine preferred for safety) throughout pregnancy.
  • Regular visual field assessment (e.g., quarterly).
  • MRI (no gadolinium) for new/worsening neuro-ophth symptoms.
• Breastfeeding: Safe. Postpartum DA compatible.

⭐ Crucial: Visual field monitoring for macroadenomas in pregnancy (risk of symptomatic enlargement).

Sheehan's Syndrome - Postpartum Pituitary Peril

• Postpartum hypopituitarism due to ischemic necrosis of the anterior pituitary gland.
• Pathophysiology: Severe postpartum hemorrhage (PPH) → profound hypotension/shock → vasospasm of hypophyseal arteries.
  • Physiologically enlarged pituitary during pregnancy is more susceptible to ischemia.
• Clinical Features:
  • Early: Failure of lactation (↓prolactin), amenorrhea/oligomenorrhea (↓LH/FSH), persistent fatigue, weakness.
  • Late: Symptoms of hypothyroidism (↓TSH - e.g., cold intolerance, dry skin), adrenal insufficiency (↓ACTH - e.g., postural hypotension, hypoglycemia), pallor, loss of axillary/pubic hair.
• Diagnosis: Low basal levels of pituitary & target organ hormones (e.g., TSH, free T4, ACTH, cortisol, FSH, LH, estradiol). Provocative hormonal tests. MRI may show an empty sella turcica in late stages.
• Management: Lifelong hormone replacement therapy (glucocorticoids first, then thyroxine, sex steroids).

⭐ Failure of lactation (agalactia) is often the earliest and most common presenting symptom of Sheehan's Syndrome.

Other Pituitary Disorders in Pregnancy - Rare But Real

• Cushing's Disease:
  • Rare; ↑maternal/fetal risks (preeclampsia, GDM, IUGR).
  • Diagnosis: 24-hr UFC, late-night salivary cortisol.
  • Management: Metyrapone (preferred); surgery if severe.
• Acromegaly:
  • Very rare; GH can ↓fertility.
  • Tumor growth possible. Visual field monitoring crucial.
  • Management: Bromocriptine if symptomatic. Discontinue somatostatin analogs.
• Diabetes Insipidus (DI):
  • Central: Vasopressin deficiency.
  • Gestational: Placental vasopressinase ↑ADH degradation; typically 3rd trimester.
  • Symptoms: Polyuria, polydipsia.
  • Management: Desmopressin (DDAVP).

  ⭐ Gestational DI is caused by placental vasopressinase degrading ADH and typically resolves postpartum.

• Lymphocytic Hypophysitis:
  • Autoimmune inflammation; late pregnancy/postpartum.
  • Symptoms: Headache, visual defects, hypopituitarism (ACTH/TSH deficiency common).
  • Management: Corticosteroids, hormone replacement.

High‑Yield Points - ⚡ Biggest Takeaways

• Physiological pituitary enlargement (due to lactotroph hyperplasia) is normal during pregnancy.
• Sheehan's syndrome: postpartum pituitary necrosis (often after PPH), causing failure of lactation and panhypopituitarism.
• Prolactinomas: most common; may enlarge. Use bromocriptine/cabergoline if visual fields compromised.
• Lymphocytic hypophysitis: autoimmune; late pregnancy/postpartum. Presents with headache, visual changes, hypopituitarism.
• Gestational Diabetes Insipidus: due to placental vasopressinase degrading ADH; responds to desmopressin (DDAVP).
• Pituitary apoplexy: rare emergency; sudden headache, visual loss, hypopituitarism. Urgent steroids treatment is crucial.