AIM • STEP 10
4th Year MBBS
Endocrine + Reproduction
Endocrine + Reproduction
Student Memory Support
Pituitary and Growth Disorders: Pathology, Clinical Evaluation, Pharmacotherapy and Surgical Management
High-yield memory reinforcement for rapid KMU professional examination revision.
1. High-Yield Flashcards
Tap each question to reveal the answer.
Which hypothalamic substance tonically inhibits prolactin secretion?
Dopamine acting on D2 receptors of lactotrophs.
What size separates a pituitary microadenoma from a macroadenoma?
Microadenoma <10 mm; macroadenoma ≥10 mm.
Which visual-field defect is classically produced by optic-chiasm compression from a pituitary macroadenoma?
Bitemporal hemianopia.
Which pituitary cell type produces growth hormone?
Somatotrophs of the anterior pituitary.
What determines whether GH excess produces gigantism or acromegaly?
Whether GH excess occurs before or after epiphyseal closure.
Which biochemical marker is most useful for initial assessment of suspected acromegaly?
Age-adjusted serum IGF-1.
What happens to GH after an oral glucose load in acromegaly?
GH fails to suppress appropriately.
How does octreotide reduce GH excess?
It activates somatostatin receptors and suppresses GH secretion.
Which drug directly antagonizes the growth-hormone receptor?
Pegvisomant.
Which important adverse effect is associated with prolonged octreotide therapy?
Gallstone formation; gastrointestinal effects and altered glucose regulation may also occur.
What is the mechanism of bromocriptine in hyperprolactinemia?
D2-receptor stimulation reduces prolactin synthesis and release.
What is the classic mechanism of Sheehan syndrome?
Severe postpartum hemorrhage or hypotension causes ischemic necrosis of the anterior pituitary.
What is an early clinical clue to Sheehan syndrome after delivery?
Failure of lactation due to prolactin deficiency.
Which measure is most useful for determining whether a short child is growing normally over time?
Height velocity from serial growth measurements.
Which operative route is commonly used for surgical management of pituitary adenomas?
Transsphenoidal resection, commonly through an endoscopic endonasal approach.
2. Mnemonics
Mnemonic Title
Anterior Pituitary Hormones
Mnemonic Word
FLAT PiG
Meaning
F = FSH, L = LH, A = ACTH, T = TSH, P = Prolactin, G = Growth hormone.
Mnemonic Title
Major Functional Pituitary Adenomas
Mnemonic Word
PACT
Meaning
P = Prolactinoma, A = ACTH-secreting corticotroph adenoma, C = GH-secreting somatotroph adenoma causing clinical growth excess, T = TSH-secreting thyrotroph adenoma.
Mnemonic Title
Acromegaly Clinical Pattern
Mnemonic Word
BIG FACE
Meaning
B = Bigger hands/feet, I = Insulin resistance, G = GH excess, F = Facial coarsening, A = Arthropathy, C = Cardiomyopathy/carpal tunnel, E = Enlarged soft tissues.
3. Memory Tables
Acromegaly vs Gigantism
| Feature | Gigantism | Acromegaly |
|---|---|---|
| Timing | Before epiphyseal closure | After epiphyseal closure |
| Main growth effect | Excessive linear growth | Acral and soft-tissue enlargement |
| Typical age | Childhood/adolescence | Adult life |
| Biochemical pathway | GH excess → ↑ IGF-1 | GH excess → ↑ IGF-1 |
Common Causes of Short Stature
| Feature | Familial Short Stature | Constitutional Delay | GH Deficiency |
|---|---|---|---|
| Parental height | Often short | May be normal | Variable |
| Height velocity | Relatively preserved | Relatively preserved | Reduced |
| Bone age | Near chronological age | Delayed | Commonly delayed |
| Weight | Generally appropriate | Generally appropriate | Relatively preserved |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- The anterior pituitary synthesizes GH, prolactin, ACTH, TSH, FSH and LH; the posterior pituitary stores and releases hypothalamic ADH and oxytocin.
- Functioning pituitary adenomas cause hormone-excess syndromes; large tumors may also compress normal pituitary tissue.
- Somatotroph adenoma → GH excess → increased IGF-1 → gigantism or acromegaly.
- A random GH level is unreliable because GH secretion is pulsatile.
- Octreotide suppresses GH secretion, whereas pegvisomant blocks GH action at its receptor.
- Bromocriptine reduces prolactin through D2-receptor stimulation and may cause nausea and postural hypotension.
- Hyperprolactinemia suppresses GnRH and can cause menstrual disturbance, infertility and hypogonadism.
- In central endocrine failure, the target hormone is low while its pituitary trophic hormone may be low or inappropriately normal.
- In combined ACTH and TSH deficiency, glucocorticoid replacement precedes thyroid-hormone replacement.
- After pituitary surgery, monitor vision, fluid balance, serum electrolytes and pituitary hormone function.
KMU Exam Trap: A prolactinoma is generally treated medically first with a dopamine agonist; the presence of a pituitary tumor does not automatically mean surgery is the first treatment.
5. Clinical Memory Hooks
Increasing shoe and ring size + coarse facial features
→
GH/IGF-1 excess → acromegaly.
→
GH/IGF-1 excess → acromegaly.
Amenorrhea + infertility + galactorrhea
→
Hyperprolactinemia → GnRH suppression.
→
Hyperprolactinemia → GnRH suppression.
Severe postpartum hemorrhage + failure to lactate
→
Anterior pituitary ischemic injury → Sheehan syndrome.
→
Anterior pituitary ischemic injury → Sheehan syndrome.
Pituitary macroadenoma + loss of temporal visual fields
→
Suprasellar extension → optic-chiasm compression.
→
Suprasellar extension → optic-chiasm compression.
6. Starred High-Yield Exam Points
- ⭐ Pituitary macroadenoma extending upward can compress the optic chiasm and produce bitemporal hemianopia.
- ⭐ Raised age-adjusted IGF-1 followed by failure of GH suppression after oral glucose strongly supports acromegaly.
- ⭐ Octreotide is a somatostatin analogue that suppresses GH secretion; gallstones are an important adverse effect.
- ⭐ Pegvisomant is a growth-hormone receptor antagonist and reduces peripheral GH action rather than GH secretion.
- ⭐ Dopamine inhibits prolactin; bromocriptine stimulates D2 receptors and reduces prolactin secretion.
- ⭐ Severe postpartum hemorrhage followed by failure of lactation is a classic clue to Sheehan syndrome.
- ⭐ In suspected combined ACTH and TSH deficiency, glucocorticoid replacement should precede thyroid-hormone replacement.