PITUITARY TUMORS Flashcards
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: 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.
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: 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.
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: 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.
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: 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).
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: 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.
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: 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.
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: 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.
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: 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.
Which drug is most commonly associated with elevated PRL levels exceeding 200 μg/L?
A. Verapamil
B. Methyldopa
C. Risperidone
D. Estrogens
Answer: C. Risperidone
Rationale: Risperidone, an antipsychotic, is known to elevate PRL levels significantly, sometimes exceeding 200 μg/L, by disrupting dopaminergic receptor function.
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: 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.
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: 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.
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.
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.
What is the primary treatment for a symptomatic microprolactinoma?
A) Surgery.
B) Radiotherapy.
C) Dopamine agonist therapy.
D) Observation only.
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.
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.
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.
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.
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.
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.
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.
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
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.
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
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.
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
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.
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
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
What is a common long-term side effect of somatostatin receptor ligand therapy?
A) Hypercalcemia
B) Gallstone formation
C) Renal insufficiency
D) Hyperthyroidism
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.
Which of the following therapies blocks peripheral GH binding to its receptor?
A) Octreotide
B) Pegvisomant
C) Lanreotide
D) Cabergoline
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)
What is the first-line treatment for a growth hormone (GH)-secreting pituitary tumor?
A) Pegvisomant
B) Cabergoline
C) Surgery
D) Radiotherapy
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.
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.
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.
