Anterior Pituitary Disorders

Question 1

Acromegaly

Answer 1

• Definition: disorder resulting from excess growth hormone in adults
• Pathophys:
  
  • GH is a counterregulatory hormone that increases glucose; increased GH → increased hepatic production of IGF-1
• S/sxs:
  
  • can be indolent
  • -DM or glucose intolerance
  • Headache
  • Acral Bony Overgrowth: frontal bossing, increased hand/foot size, mandibular enlargement
  • Soft-Tissue Swelling: heel pad thickness, ring tightening, large nose
  • • PE:
  • Hyperhidrosis +/- oily skin
  • deep voice
  • Carpal tunnel syndrome (d/t increased pressure on nerves)
  • proximal muscle weakness, acanthosis nigricans, skin tags
  • Hypertension (d/t salt retention & expansion of ECV)
  • Polyps in the colon
• Dx:
  
  • Serum IGF-1 to screen: must interpret ranges of age/sex
    
    • *if positive then → oral glucose suppression test: 75g PO glucose → measure serum GH levels at 30 & 60 min (normal <1g); GH normally stimulates glucose release, there is negative feedback on GH from glucose, so if you give glucose and GH remains elevated = acromegaly
  • MRI:
    
    • evaluate for sellar or pituitary lesions
• Tx:
  
  • refer to endocrinology
  • Surgery: removal of active tumors
  • Somatostatin analogs: octreotide or lanreotide, b/c somatostatin inhibits GH release
• Complications:
  
  • congestive HF
  • Obstructive Sleep Apnea

Question 2

Gigantism

Answer 2

• Definition:
  
  • disorder resulting from excess growth hormone in children (when they have open growth plates) → excessive long bone growth
• S/sxs:
  
  • excessively fast growth in height and weight
  • DM
  • Carpal Tunnel Syndrome
• PE:
  
  • macrocephaly, projection of lower jaw, soft tissue swelling, increased size of organs
• Dx:
  
  • Serum IGF-1 to screen: must interpret ranges of age/sex
    
    • *if positive then → oral glucose suppression test: 75g PO glucose → measure serum GH levels at 30 & 60 min (normal <1g)
• Tx:
  
  • refer to endo
  • Surgery: removal of active tumors
  • Somatostatin analogs: octreotide or lanreotide, b/c somatostatin inhibits GH release

Question 3

Pituitary Apoplexy

Answer 3

aka Watershed Infarction

• Definition: hemorrhage or infarction of the pituitary gland. commonly caused by bleeding inside a benign pituitary tumor (d/t friable blood vessels)
• Anatomy:
  
  • most blood supply to anterior pituitary is venous & small portion comes from middle hypophyseal artery
• S./sxs:
  
  • **Sudden onset
  • severe headache
  • Peripheral Vision Loss (Bilateral)
  • Ophthalmoplegia: paralysis of eye muscles
  • cardiovascular collapse
  • Severe:
    
    • hypoglycemia (d/t low GH)
    • hypotension (d/t low cortisol → this is most dangerous)
    • Shock, CNS hemorrhage, death
• Dx:
  
  • Endocrine studies:
    
    • all pituitary hormonal deficiencies can occur, but cortisol is the most severe & dangerous
  • Urgent CT:
    
    • exam for intratumoral hemorrhage, pituitary stalk deviation, or compression
  • MRI: once clinically stable
• Tx:
  
  • Endocrine Emergency
  • IV corticosteroid 6-8 hours until BP is stable
  • Surgery: decompression, hematoma evacuation
  • assess for other pituitary hormone deficiencies

Question 4

Non-Functional Pituitary Adenoma

Answer 4

• secretes alpha subunit
• Microadenomas < 1cm, Macroadenomas > 1 cm
• PE:
  
  • *Visual Field Exam:
  • Bitemporal hemianopia (d/t optic chiasm compression) → “Tunnel vision”
  • Headache & Visual changes
• Dx;
  
  • MRI = study of choice to look for sellar lesions
• Tx:
  
  • Surgery for decompression if visual field deficit confirmed by optho

Question 5

Prolactinoma

Answer 5

• Definition:
  
  • benign tumor of the lactotroph cell → increased secretion of PRL (prolactin)
  • Most common type of pituitary adenoma.
  • PRL functions: lactation, suppression of GnRH (negative feedback) → low LH/FSH, suppression of pregnancy, dopamine suppresses PRL
• S/sxs:
  
  • Galactorrhea (milky nipple discharge)
  • Women:
    
    • Amenorrhea
    • Infertility
  • Men:
    
    • Hypogonadism: erectile dysfunction, decreased libido, interfility, gynecomastia
• PE:
  
  • *Visual Field Exam:
    
    • Bitemporal hemianopia (d/t optic chiasm compression) → “Tunnel vision”
    • headache & visual changes
• Dx: “Dope Bro you’re lactating” - Karen
  
  • Endocrine studies:
    
    • increased prolactin (AM fasting), decreased FSH/LH, check TSH/GH/ACTH
  • MRI = study of choice to look for sellar lesions if prolactin is elevated on repeat testing
  • exclude medications & CKD as causes before repeating prolactin
• Tx:
  
  • Dopamine Agonists: cabergoline or Bromocriptine are first-line.
  • Monitor Prolactin level & repeat MRI Q3-6 months
  • Ophtho referral: if visual field deficit is present on initial exam
  • Neurosurgery referral: for decompression if V deficit confirmed by optho

Question 6

Somatotroph

Answer 6

Acromegaly

• Definition: growth hormone secreting pituitary adenoma → acromegaly (adults) or gigantism (children)
• Tx:
  
  • tx the hypersecretion
  • transsphenoidal surgery = definitive

Question 7

Corticotroph

Answer 7

Cushing’s Disease

• Definition: ACTH-secreting pituitary adenoma → hypercortisolism
• Tx:
  
  • tx the hypersecretion
  • transsphenoidal surgery = definitive

Question 8

Thyrotroph

Answer 8

TSH-secreting

• Definition: benign pituitary adenoma that secretes TSH in an autonomous fashion. Rare cause of hyperthyroidism (<1% of all cases)
• S/sxs:
  
  • diffuse goiter
  • hyperthyroidism:
    
    • anxiety, heat intolerance, weight loss, fatigue, tachycardia, palpitations, fine, tremor, oligomenorrhea
• PE:
  
  • **Visual field exam
  • Bitemporal hemianopia & headache (d/t optic chiasm compression)
• Dx:
  
  • secondary hyperthyroidism: increased TSH & increased Free T4
  • Radioactive Uptake Scan: diffuse increased uptake (like Grave’s)
  • MRI: to detect adenoma
• Tx:
  
  • tx the hypersecretion
  • transsphenoidal surgery = definitive