PITUITARY TUMORS

Question 1

Which of the following is a screening test for acromegaly?
A. Serum prolactin (PRL)
B. Serum IGF-1
C. 24-hour urinary free cortisol
D. Free T4, free T3, and TSH

Answer 1

Answer: B. Serum IGF-1
Rationale: The screening test for acromegaly is serum IGF-1. It should be interpreted relative to age- and sex-matched controls, and oral glucose tolerance testing may also be used to confirm the diagnosis.

Question 2

In normal individuals, what should happen to growth hormone (GH) levels during an oral glucose tolerance test for acromegaly?
A. Increase to ≥10 μg/L
B. Remain unchanged
C. Suppress to <1 μg/L
D. Suppress to <5 μg/L

Answer 2

Answer: C. Suppress to <1 μg/L
Rationale: In normal individuals, GH levels should suppress to <1 μg/L during an oral glucose tolerance test. Failure to suppress suggests acromegaly.

Question 3

When screening for prolactinoma, what additional step is recommended if serum prolactin (PRL) is elevated?
A. Perform an ACTH assay
B. Order an MRI of the sella
C. Measure urinary free cortisol
D. Conduct an oral glucose tolerance test

Answer 3

Answer: B. Order an MRI of the sella
Rationale: If serum PRL is elevated, an MRI of the sella is recommended to evaluate for the presence of a prolactinoma after excluding medication-induced hyperprolactinemia.

Question 4

Which test is used to distinguish adrenal adenoma from ectopic ACTH or Cushing’s disease?
A. 24-hour urinary free cortisol
B. Late-night salivary cortisol
C. Dexamethasone suppression test
D. ACTH assay

Answer 4

Answer: D. ACTH assay
Rationale: An ACTH assay can distinguish between adrenal adenoma (ACTH suppressed) and ectopic ACTH or Cushing’s disease (ACTH normal or elevated).

Question 5

Which of the following is characteristic of a TSH-producing adenoma?
A. Low TSH with elevated free T4 and T3
B. Inappropriately normal or high TSH with elevated free T4 and T3
C. Elevated ACTH with suppressed cortisol
D. Elevated prolactin levels

Answer 5

Answer: B. Inappropriately normal or high TSH with elevated free T4 and T3
Rationale: A TSH-producing adenoma is characterized by an inappropriately normal or high TSH in the setting of elevated free T4 and T3 levels.

Question 6

Which of the following tests is most useful in screening for Cushing’s disease?
A. Serum IGF-1
B. Serum PRL
C. 24-hour urinary free cortisol
D. TRH stimulation test

Answer 6

Answer: C. 24-hour urinary free cortisol
Rationale: A 24-hour urinary free cortisol test is a primary screening tool for Cushing’s disease. Dexamethasone suppression testing and ACTH assays are also used for diagnosis.

Question 7

Which of the following is the most common cause of hyperprolactinemia?
A. Renal failure
B. PRL-secreting pituitary adenomas (prolactinomas)
C. Chest wall stimulation or trauma
D. Primary hypothyroidism

Answer 7

Answer: B. PRL-secreting pituitary adenomas (prolactinomas)
Rationale: Prolactinomas are the most common cause of PRL levels >200 μg/L and represent the most frequent cause of hyperprolactinemia overall.

Question 8

Which physiologic condition is a significant cause of hyperprolactinemia?
A. Pituitary stalk compression
B. Pregnancy and lactation
C. Primary hypothyroidism
D. Chronic renal failure

Answer 8

Answer: B. Pregnancy and lactation
Rationale: Pregnancy and lactation are important physiologic causes of hyperprolactinemia due to the natural increase in PRL levels during these periods.

Question 9

Which drug is most commonly associated with elevated PRL levels exceeding 200 μg/L?
A. Verapamil
B. Methyldopa
C. Risperidone
D. Estrogens

Answer 9

Answer: C. Risperidone
Rationale: Risperidone, an antipsychotic, is known to elevate PRL levels significantly, sometimes exceeding 200 μg/L, by disrupting dopaminergic receptor function.

Question 10

What is the hallmark presentation of hyperprolactinemia in women?
A. Visual loss
B. Osteopenia and reduced muscle mass
C. Amenorrhea, galactorrhea, and infertility
D. Diminished libido and weight gain

Answer 10

Answer: C. Amenorrhea, galactorrhea, and infertility
Rationale: These are the classic symptoms of hyperprolactinemia in women, resulting from gonadotropin suppression and PRL-induced effects on estrogen levels.

Question 11

Which of the following conditions is most likely to cause mild hyperprolactinemia (30–100 μg/L)?
A. Plurihormonal pituitary adenomas
B. Antidepressant use
C. Nipple stimulation
D. Primary hypothyroidism

Answer 11

Answer: D. Primary hypothyroidism
Rationale: Primary hypothyroidism can cause mild hyperprolactinemia due to compensatory TRH secretion. Levels usually fall within the range of 30–100 μg/L.

Question 12

What is the first step in managing elevated prolactin levels?
A) Start dopamine agonist therapy.
B) Exclude secondary causes of hyperprolactinemia.
C) Perform pituitary surgery.
D) Monitor prolactin levels without intervention.

Answer 12

Correct Answer: B) Exclude secondary causes of hyperprolactinemia.
Rationale: The initial step in managing elevated prolactin is to rule out secondary causes (e.g., medications, hypothyroidism, or renal insufficiency) and to confirm MRI evidence of a pituitary mass.

Question 13

What is the primary treatment for a symptomatic microprolactinoma?
A) Surgery.
B) Radiotherapy.
C) Dopamine agonist therapy.
D) Observation only.

Answer 13

Correct Answer: C) Dopamine agonist therapy.
Rationale: Dopamine agonists (e.g., cabergoline or bromocriptine) are the first-line treatment for microprolactinomas, as they can reduce prolactin levels and tumor size.

Question 14

In patients with macroadenomas, what should be assessed initially besides initiating dopamine agonist therapy?
A) Bone mineral density.
B) Visual fields and pituitary reserve function.
C) Prolactin receptor antibodies.
D) Liver function tests.

Answer 14

Correct Answer: B) Visual fields and pituitary reserve function.
Rationale: Macroadenomas can compress surrounding structures, necessitating visual field testing and evaluation of pituitary reserve to assess possible deficiencies.

Question 15

What is the next step if a macroadenoma does not show tumor shrinkage or normalization of prolactin levels after 4 months of dopamine agonist therapy?
A) Continue monitoring.
B) Increase the dopamine agonist dose.
C) Change to a different dopamine agonist.
D) Consider surgery.

Answer 15

Correct Answer: D) Consider surgery.
Rationale: Surgery is indicated for resistant cases where there is no tumor shrinkage, persistent hyperprolactinemia, or tumor growth despite adequate dopamine agonist therapy.

Question 16

If tumor shrinkage occurs in a macroadenoma and prolactin levels normalize, how should the patient be managed long-term?
A) Discontinue all therapy.
B) Perform surgery to remove the residual tumor.
C) Monitor prolactin levels and repeat MRI annually.
D) Initiate radiotherapy.

Answer 16

Correct Answer: C) Monitor prolactin levels and repeat MRI annually.
Rationale: In cases of tumor shrinkage and normalized prolactin levels, annual monitoring ensures continued control and checks for potential recurrence or progression.

Question 17

What is the primary laboratory test used to screen for acromegaly?
A) Serum prolactin levels
B) Serum IGF-1 levels
C) Serum calcium levels
D) Thyroid-stimulating hormone (TSH) levels

Answer 17

Correct Answer: B) Serum IGF-1 levels
Rationale: Elevated age-matched serum IGF-1 levels are a hallmark of acromegaly and are used as the primary screening tool when clinical suspicion arises.

Question 18

Which test confirms the diagnosis of acromegaly?
A) Random growth hormone (GH) measurement
B) GH suppression test after oral glucose load
C) MRI of the pituitary gland
D) Serum cortisol measurement

Answer 18

Correct Answer: B) GH suppression test after oral glucose load
Rationale: Failure of GH suppression to less than 0.4 µg/L within 1–2 hours of a 75 g oral glucose load confirms acromegaly. This test is the diagnostic gold standard.

Question 19

What is the initial treatment of choice for most patients with acromegaly?
A) Somatostatin receptor ligands (SRLs)
B) Transsphenoidal surgical resection
C) Pegvisomant
D) Radiation therapy

Answer 19

Correct Answer: B) Transsphenoidal surgical resection
Rationale: Surgical removal of the GH-secreting adenoma via the transsphenoidal approach is the preferred primary treatment for most patients.

Question 20

Which drug class is commonly used as adjuvant therapy to reduce GH secretion and achieve biochemical control in acromegaly?
A) Dopamine agonists
B) Growth hormone receptor antagonists
C) Somatostatin receptor ligands (SRLs)
D) Beta-blockers

Answer 20

Correct Answer: C) Somatostatin receptor ligands (SRLs)
Rationale: SRLs, such as octreotide and lanreotide, are commonly used for preoperative tumor shrinkage, symptom relief, and biochemical control when surgery is not sufficient or feasible.

• SRLs exert their therapeutic effects through SST2 and SST5 receptor subtypes, both expressed by GH-secreting tumors
• The preferred medical treatments for patients with acromegaly include long-acting injectable SRL depot formulations of octreotide and lanreotide as well as oral octreotide capsules

Question 21

What is a common long-term side effect of somatostatin receptor ligand therapy?
A) Hypercalcemia
B) Gallstone formation
C) Renal insufficiency
D) Hyperthyroidism

Answer 21

Correct Answer: B) Gallstone formation
Rationale: SRLs reduce gallbladder contractility and emptying, leading to long-term complications such as asymptomatic cholesterol gallstones or echogenic sludge in up to 30% of patients.

• Transient nausea, abdominal discomfort, fat malabsorption, diarrhea, and flatulence
• Gallbladder contractility and emptying are attenuated; up to 30% of patients develop long-term echogenic sludge or asymptomatic cholesterol gallstones.

Question 22

Which of the following therapies blocks peripheral GH binding to its receptor?
A) Octreotide
B) Pegvisomant
C) Lanreotide
D) Cabergoline

Answer 22

Correct Answer: B) Pegvisomant
Rationale: Pegvisomant is a GH receptor antagonist that prevents endogenous GH from binding to its receptor, thereby reducing its peripheral effects.

• Pegvisomant antagonizes endogenous GH action by blocking peripheral GH binding to its receptor
  
  • Daily subcutaneous injection (10–30 mg)

Question 23

What is the first-line treatment for a growth hormone (GH)-secreting pituitary tumor?
A) Pegvisomant
B) Cabergoline
C) Surgery
D) Radiotherapy

Answer 23

Correct Answer: C) Surgery
Rationale: Surgical resection is the initial treatment for GH-secreting pituitary tumors when feasible, as it offers the best chance for immediate biochemical control.

Question 24

If a patient remains uncontrolled after surgery, what is the next recommended step?
A) Start somatostatin receptor ligand (SRL) therapy.
B) Proceed directly to radiotherapy.
C) Initiate pegvisomant.
D) Use a combination of SRL and pegvisomant.

Answer 24

Correct Answer: A) Start somatostatin receptor ligand (SRL) therapy.
Rationale: If surgery does not achieve biochemical control, SRLs, such as octreotide or lanreotide, are typically the next step to reduce GH secretion.

Question 25

What is the recommended management if an SRL fails to control GH secretion?
A) Increase the SRL dose
B) Add pegvisomant
C) Consider reoperation
D) All of the above

Answer 25

Correct Answer: D) All of the above
Rationale: If an SRL does not provide adequate control, options include increasing the dose, combining SRL with pegvisomant, or considering reoperation to improve outcomes.

Question 26

What combination therapy is recommended when both SRL monotherapy and pegvisomant fail to achieve control?
A) Pasireotide alone
B) SRL plus pegvisomant
C) Pasireotide plus radiotherapy
D) Radiation therapy alone

Answer 26

Correct Answer: B) SRL plus pegvisomant
Rationale: The combination of SRL and pegvisomant is often used when monotherapy with either fails to control GH and IGF-1 levels.

Question 27

When is radiotherapy indicated in the management of acromegaly?
A) As the first-line treatment
B) When all other medical and surgical treatments fail
C) After surgery in all patients
D) To replace SRL therapy

Answer 27

Correct Answer: B) When all other medical and surgical treatments fail
Rationale: Radiotherapy is used as a last-line option for patients whose GH/IGF-1 levels remain uncontrolled despite surgery and medical therapy.

Question 28

What monitoring is required for patients who achieve biochemical control?
A) Annual brain MRI scans only
B) IGF-1 levels at regular intervals
C) Reassessment of tumor size every 5 years
D) No further follow-up is necessary

Answer 28

Correct Answer: B) IGF-1 levels at regular intervals
Rationale: Monitoring IGF-1 levels ensures long-term biochemical control and detects any recurrence or progression of disease.

Question 29

When is cabergoline indicated in the management of acromegaly?
A) As a first-line therapy for large invasive macroadenomas
B) As an adjuvant option when IGF-1 levels remain mildly elevated
C) After SRL and pegvisomant have failed
D) Only for patients who cannot undergo surgery

Answer 29

Correct Answer: B) As an adjuvant option when IGF-1 levels remain mildly elevated
Rationale: Cabergoline, a dopamine agonist, is considered in cases of mild postoperative GH/IGF-1 elevations as part of medical management.

Question 30

Which of the following is the most common etiology of ACTH-dependent Cushing’s syndrome caused by a pituitary tumor?
A) Small-cell lung cancer
B) Bronchial carcinoid tumor
C) Pituitary corticotrope adenoma
D) Adrenal cortical adenoma

Answer 30

Correct Answer: C) Pituitary corticotrope adenoma
Rationale: Pituitary corticotrope adenoma is the primary cause of ACTH-dependent Cushing’s syndrome related to the pituitary gland.

Question 31

Which clinical feature is more characteristic of ectopic ACTH secretion than a pituitary tumor?
A) Slow onset of symptoms
B) Severe myopathy
C) Microadenoma presence on imaging
D) Serum potassium >3.3 μg/L

Answer 31

Correct Answer: B) Severe myopathy
Rationale: Ectopic ACTH secretion often presents with rapid onset, pigmentation, and severe myopathy, which are less typical in pituitary ACTH-dependent Cushing’s syndrome.

Question 32

What differentiates a pituitary ACTH tumor from ectopic ACTH secretion in the dexamethasone suppression test (low-dose and high-dose)?
A) Both suppress cortisol to <5 μg/dL
B) Cortisol suppression to <5 μg/dL is more likely in pituitary tumors
C) Neither condition suppresses cortisol to <5 μg/dL
D) Ectopic ACTH secretion shows 80% UFC suppression

Answer 32

Correct Answer: B) Cortisol suppression to <5 μg/dL is more likely in pituitary tumors
Rationale: High-dose dexamethasone suppression is more effective in suppressing cortisol production in pituitary ACTH tumors compared to ectopic sources.

Question 33

What laboratory test helps distinguish ACTH-independent from ACTH-dependent Cushing’s syndrome?
A) Inferior petrosal sinus sampling
B) Basal plasma ACTH levels
C) High-dose dexamethasone suppression test
D) 24-hour UFC

Answer 33

Correct Answer: B) Basal plasma ACTH levels
Rationale: Basal plasma ACTH levels are used to differentiate ACTH-independent causes (low ACTH, such as adrenal tumors) from ACTH-dependent causes (elevated ACTH, such as pituitary or ectopic sources).

Question 34

During inferior petrosal venous sampling, what ACTH ratio confirms a pituitary source of ACTH secretion?
A) Peripheral ACTH > Inferior petrosal ACTH
B) Inferior petrosal:peripheral ACTH >2
C) Inferior petrosal:peripheral ACTH <2
D) UFC suppression >80%

Answer 34

Correct Answer: B) Inferior petrosal:peripheral ACTH >2
Rationale: A ratio of inferior petrosal:peripheral ACTH >2 (at baseline) or >3 (after CRH stimulation) confirms pituitary Cushing’s syndrome.

Question 35

Which of the following is the first-line treatment for Cushing’s disease?
A) Pituitary irradiation
B) Low-dose cortisol replacement therapy
C) Transsphenoidal surgical resection
D) Repeat surgery

Answer 35

Correct Answer: C) Transsphenoidal surgical resection
Rationale: Selective transsphenoidal resection of the pituitary tumor is the treatment of choice for Cushing’s disease.

Question 36

What is a common postoperative condition following successful tumor resection for Cushing’s disease?
A) Permanent adrenal insufficiency
B) Symptomatic ACTH deficiency
C) Persistent hypercortisolism
D) Hypokalemia

Answer 36

Correct Answer: B) Symptomatic ACTH deficiency
Rationale: After successful resection, most patients experience temporary ACTH deficiency requiring low-dose cortisol replacement for up to 12 months.