1. A 27-year-old woman presents with 8 months of amenorrhea, galactorrhea, and difficulty conceiving. Serum prolactin is 165 ng/mL, thyroid-stimulating hormone (TSH) is normal, and a pregnancy test is negative. Pituitary MRI shows a 6 mm microadenoma without suprasellar extension. She wishes to restore fertility. Which of the following is the most appropriate initial treatment and the correct statement of its therapeutic goal?
A) Transsphenoidal surgery, with the goal of immediate tumor removal, because microprolactinomas in women seeking fertility are best managed surgically to avoid teratogenic drug exposure.
B) Estrogen-progestin oral contraceptive therapy, with the goal of restoring menses, because hormonal replacement corrects the amenorrhea regardless of the underlying prolactin elevation.
C) Observation with serial prolactin and MRI, with the goal of deferring treatment, because a 6 mm microadenoma rarely causes symptoms and will likely resolve spontaneously.
D) Cabergoline, with the goals of normalizing serum prolactin, restoring ovulatory menstrual cycles and fertility, and reducing tumor size; cabergoline is the first-line agent because it produces high rates of prolactin normalization with twice-weekly dosing and favorable tolerability.
E) Bromocriptine as lifelong therapy, with the goal of permanent prolactin suppression, because microprolactinomas always require indefinite treatment and cabergoline is contraindicated in women of reproductive age.
ANSWER: D
Rationale:
This patient has a symptomatic microprolactinoma causing hyperprolactinemic amenorrhea and infertility. First-line therapy is a dopamine agonist, and cabergoline is the preferred agent because it achieves prolactin normalization in 85 to 95% of microadenomas, is dosed twice weekly owing to its long half-life, and is better tolerated than bromocriptine. The therapeutic goals in this patient are to normalize serum prolactin, restore ovulatory menstrual cycles and fertility, and reduce tumor volume; relief of hyperprolactinemia removes the suppression of gonadotropin-releasing hormone pulsatility that causes the amenorrhea, allowing ovulation to resume.
Option A: Option A is incorrect because microprolactinomas are managed medically with dopamine agonists as first-line therapy, not surgically; transsphenoidal surgery is reserved for patients intolerant of or resistant to dopamine agonists, and dopamine agonists are effective at restoring fertility without the risks of surgery.
Option B: Option B is incorrect because an estrogen-progestin contraceptive would suppress rather than restore fertility and does not address the underlying prolactin excess; it would also be counterproductive in a patient whose explicit goal is conception.
Option C: Option C is incorrect because this microadenoma is symptomatic — causing amenorrhea, galactorrhea, and infertility — so observation is inappropriate; symptomatic hyperprolactinemia warrants treatment to restore gonadal function.
Option E: Option E is incorrect because cabergoline is not contraindicated in women of reproductive age and is in fact the preferred first-line agent; microprolactinomas do not always require indefinite therapy, since drug withdrawal can be considered after sustained normoprolactinemia with a clear MRI.
2. A 46-year-old man presents with progressive bitemporal hemianopia and headache. MRI reveals a 32 mm sellar mass with suprasellar extension compressing the optic chiasm. Serum prolactin is reported as 48 ng/mL. The neurosurgery team is preparing to take him for urgent decompressive transsphenoidal surgery for a presumed non-functioning macroadenoma. Which of the following is the most appropriate next step before proceeding to surgery?
A) Proceed immediately to transsphenoidal surgery, because the prolactin of 48 ng/mL is only mildly elevated and reflects stalk-effect hyperprolactinemia from a non-functioning adenoma, which requires surgical decompression.
B) Request a 1:100 serial dilution of the serum prolactin before surgery, because a very large pituitary mass with only a mildly elevated prolactin is the classic presentation of the hook effect; if dilution reveals a markedly elevated true prolactin, the lesion is a macroprolactinoma that should be treated first with cabergoline, which can shrink the tumor and relieve the chiasmal compression without surgery.
C) Begin high-dose intravenous glucocorticoids and observe, because the visual loss is most likely due to inflammatory hypophysitis rather than tumor compression, and steroids will reverse the deficit.
D) Order a serum insulin-like growth factor-1 (IGF-1) level, because the most likely diagnosis is a growth hormone-secreting macroadenoma, and confirming acromegaly will direct therapy to a somatostatin analog.
E) Proceed to surgery but send intraoperative frozen section, because the prolactin level is irrelevant to management and only histology can determine the tumor type and guide postoperative therapy.
ANSWER: B
Rationale:
This vignette is the classic clinical trap for the hook effect. A very large sellar mass (32 mm) with chiasmal compression but only a mildly elevated prolactin (48 ng/mL) should raise immediate suspicion that the immunometric assay has been saturated by an extremely high prolactin concentration, producing a falsely low measured value. The correct next step is to request a serial dilution (typically 1:100) of the serum before committing to surgery. If the diluted value rises markedly, the lesion is a macroprolactinoma — which should be treated first with cabergoline, since dopamine agonists shrink macroprolactinomas in the large majority of patients and can relieve chiasmal compression and restore vision without an operation. Missing this step risks an unnecessary operation on a medically treatable tumor.
Option A: Option A is incorrect because the mildly elevated prolactin in the presence of a very large mass should not be assumed to represent stalk effect; stalk-effect hyperprolactinemia generally produces values below about 150 to 200 ng/mL, but the hook effect must be excluded by dilution before attributing a large mass to a non-functioning adenoma.
Option C: Option C is incorrect because the clinical picture of a large sellar mass compressing the chiasm is far more consistent with a macroadenoma than with hypophysitis, and empiric high-dose steroids would not address a macroprolactinoma; the priority is to exclude the hook effect.
Option D: Option D is incorrect because, although IGF-1 is reasonable in a full pituitary workup, the immediate decision point here is whether the mass is a macroprolactinoma masked by the hook effect, since that single finding could replace surgery with medical therapy; the vignette has no features pointing specifically to acromegaly.
Option E: Option E is incorrect because the prolactin level is highly relevant — excluding the hook effect could spare the patient surgery entirely — so proceeding to the operating room without serial dilution risks operating on a tumor that would respond to cabergoline.
3. A 30-year-old woman with a microprolactinoma has achieved normoprolactinemia and regular ovulatory cycles on cabergoline 0.5 mg twice weekly. She and her partner now wish to conceive. She has no visual symptoms and her most recent MRI shows a stable 5 mm microadenoma. Which of the following is the most appropriate management plan for her dopamine agonist therapy as she attempts pregnancy?
A) Counsel her that, once pregnancy is confirmed, dopamine agonist therapy can generally be discontinued in microadenoma patients because the risk of clinically significant tumor expansion during pregnancy is low; if continued dopamine agonist therapy is desired or needed, switching to bromocriptine is an option given its longer and larger pregnancy safety database.
B) Continue cabergoline at the current dose throughout pregnancy without interruption, because uninterrupted prolactin suppression is required to prevent rapid tumor growth in all prolactinoma patients during gestation.
C) Discontinue cabergoline now and switch to a long-acting somatostatin analog before conception, because somatostatin analogs are safer than dopamine agonists in early pregnancy and provide equivalent prolactin control.
D) Proceed to transsphenoidal surgery before conception to remove the microadenoma, because pregnancy is contraindicated while a prolactinoma remains in situ.
E) Increase the cabergoline dose before conception to maximally suppress the tumor, then continue the higher dose through the first trimester to prevent estrogen-driven tumor enlargement.
ANSWER: A
Rationale:
For a woman with a microprolactinoma who wishes to conceive, the key management principles are that microadenomas carry a low risk of symptomatic expansion during pregnancy (on the order of a few percent), and that dopamine agonists can generally be discontinued once pregnancy is confirmed in microadenoma patients. If continued dopamine agonist therapy is desired or required, bromocriptine is a reasonable choice because it has the longest and largest pregnancy safety database, accumulated over four decades of fertility use; many centers therefore switch women planning pregnancy from cabergoline to bromocriptine, or simply discontinue the agonist at confirmation of pregnancy in microadenoma patients. This individualized approach balances fetal exposure against the low expansion risk.
Option B: Option B is incorrect because uninterrupted dopamine agonist therapy throughout pregnancy is not required for microadenomas; the low expansion risk allows discontinuation at pregnancy confirmation, and routine continuation would expose the fetus unnecessarily.
Option C: Option C is incorrect because somatostatin analogs are not effective therapy for prolactinoma and are not the preferred agents in pregnancy; prolactinomas are dopamine-responsive, and switching to a somatostatin analog would not control prolactin.
Option D: Option D is incorrect because a stable microadenoma is not a contraindication to pregnancy and does not require pre-conception surgery; medical management is standard, and surgery is reserved for dopamine agonist intolerance or resistance.
Option E: Option E is incorrect because increasing the cabergoline dose and continuing a higher dose through the first trimester is unnecessary for a microadenoma with low expansion risk and would increase fetal drug exposure without benefit; the standard approach is discontinuation or switching to bromocriptine, not dose escalation.
4. A 39-year-old woman with a microprolactinoma has been on cabergoline for 4 years. Her serum prolactin has been normal for 28 consecutive months, and her most recent pituitary MRI shows no visible tumor. She asks whether she can stop the medication. Which of the following is the most appropriate plan regarding cabergoline withdrawal and subsequent monitoring?
A) She must remain on cabergoline indefinitely, because prolactinomas always recur if therapy is stopped, and withdrawal is never appropriate once a tumor has been identified.
B) Stop cabergoline abruptly and recheck prolactin only if symptoms such as galactorrhea or amenorrhea recur, because asymptomatic patients do not require scheduled biochemical monitoring after withdrawal.
C) Continue cabergoline but reduce the dose by half indefinitely, because partial dosing maintains tumor suppression while minimizing valvulopathy risk, and full withdrawal is contraindicated in any patient with a prior microadenoma.
D) Stop cabergoline only after a confirmatory transsphenoidal biopsy demonstrates absence of residual lactotroph tissue, because imaging alone cannot establish candidacy for withdrawal.
E) She meets withdrawal candidacy criteria — at least 2 years of sustained normoprolactinemia and no visible tumor on MRI — so cabergoline can be tapered and discontinued; after withdrawal, prolactin should be monitored at 1, 3, and 6 months and then annually, recognizing that recurrence occurs in roughly 30 to 35% within the first year and up to about 70% by 5 years, with cabergoline restarted if prolactin rises again.
ANSWER: E
Rationale:
This patient meets the standard candidacy criteria for cabergoline withdrawal: at least 2 years of sustained normoprolactinemia (she has 28 months) and no visible tumor on MRI. The appropriate plan is to taper and discontinue cabergoline, then monitor prolactin at 1, 3, and 6 months and annually thereafter. It is essential to counsel her that recurrence is common — approximately 30 to 35% within the first year and up to about 70% by 5 years — and that recurrence is managed by restarting cabergoline, to which response is generally preserved. This structured withdrawal-and-monitoring approach is the evidence-based management for an eligible patient.
Option A: Option A is incorrect because withdrawal is appropriate in eligible patients; prolactinomas do not always recur, and many patients sustain normoprolactinemia after withdrawal, so indefinite mandatory therapy is not required.
Option B: Option B is incorrect because scheduled biochemical monitoring (prolactin at defined intervals) is required after withdrawal rather than relying on symptom recurrence alone, since prolactin can rise before symptoms reappear and early detection guides timely re-treatment.
Option C: Option C is incorrect because full withdrawal is appropriate for this eligible patient and is not contraindicated; indefinite half-dose therapy is unnecessary, and there is no rule prohibiting withdrawal in patients with a prior microadenoma who meet criteria.
Option D: Option D is incorrect because candidacy for withdrawal is established by biochemical and imaging criteria, not by transsphenoidal biopsy; surgical biopsy is not part of the withdrawal decision and would expose the patient to unnecessary operative risk.
5. A 52-year-old woman with severe Cushing disease has marked hypercortisolism with a urinary free cortisol (UFC) more than 8 times the upper limit of normal, poorly controlled hypertension, hypokalemia, hyperglycemia, and a recent psychotic episode. She is scheduled for repeat transsphenoidal surgery in 3 weeks, and the team wants to rapidly lower cortisol before the operation to reduce perioperative risk. Which of the following is the most appropriate pharmacological choice for rapid preoperative cortisol control, with appropriate monitoring?
A) Mifepristone, because it rapidly lowers serum cortisol and urinary free cortisol, and the falling cortisol levels can be used to titrate the dose preoperatively.
B) Cabergoline monotherapy, because dopamine agonists reliably normalize cortisol within days in the majority of Cushing disease patients and are the fastest-acting option for severe hypercortisolism.
C) A steroidogenesis inhibitor such as ketoconazole, metyrapone, or osilodrostat, because these agents directly block adrenal cortisol synthesis and can rapidly reduce cortisol to control severe hypercortisolism before surgery; the choice requires monitoring appropriate to the agent (for example, liver function tests for ketoconazole; electrolytes and blood pressure for metyrapone and osilodrostat) and vigilance for adrenal insufficiency.
D) Pasireotide long-acting release administered monthly, because its slow onset over several months provides smooth, sustained cortisol reduction ideal for the 3-week preoperative window.
E) Observation with electrolyte repletion alone, because pharmacological cortisol lowering before pituitary surgery worsens surgical outcomes and should be avoided.
ANSWER: C
Rationale:
In severe hypercortisolism requiring rapid preoperative control, adrenal steroidogenesis inhibitors are the appropriate choice because they directly block cortisol biosynthesis and can lower cortisol relatively quickly. Ketoconazole, metyrapone, and osilodrostat are all used in this setting; the selection depends on patient factors and the monitoring each requires — liver function tests for ketoconazole, and electrolytes and blood pressure for metyrapone (DOC-driven mineralocorticoid excess) and osilodrostat (aldosterone reduction), with vigilance for adrenal insufficiency as cortisol falls. This direct, titratable cortisol-lowering is exactly what is needed to reduce perioperative risk from severe hypercortisolism.
Option A: Option A is incorrect because mifepristone does not lower cortisol secretion — it blocks the glucocorticoid receptor, and cortisol and UFC actually rise during therapy, so cortisol cannot be used to titrate the dose; it is indicated for hyperglycemia in Cushing syndrome, not for rapid biochemical cortisol lowering.
Option B: Option B is incorrect because cabergoline monotherapy does not reliably or rapidly normalize cortisol in Cushing disease; its efficacy is partial and often lost over time, making it unsuitable as the primary agent for rapid control of severe hypercortisolism.
Option D: Option D is incorrect because pasireotide long-acting release has a slow onset and would not achieve the rapid cortisol reduction needed within a 3-week preoperative window; it also frequently causes hyperglycemia, which is already a problem in this patient.
Option E: Option E is incorrect because severe hypercortisolism with hypertension, hypokalemia, hyperglycemia, and psychosis warrants active cortisol lowering before surgery to reduce perioperative risk; observation with electrolyte repletion alone would leave the dangerous hypercortisolism untreated.
6. A 48-year-old woman with Cushing disease has had a good response to pasireotide, with urinary free cortisol (UFC) falling into the normal range over 8 weeks. However, she has developed new hyperglycemia, with fasting glucose now 184 mg/dL and HbA1c risen to 7.9%; she had no prior diabetes. The team wishes to continue the effective pasireotide therapy. Which of the following is the most appropriate management of her hyperglycemia?
A) Start a glucagon-like peptide-1 (GLP-1) receptor agonist as the preferred first-line agent, because pasireotide causes hyperglycemia chiefly by suppressing insulin secretion through somatostatin receptors on the pancreatic islet, and GLP-1 receptor agonists stimulate insulin secretion and suppress glucagon through a pathway that remains effective despite somatostatin receptor activation, allowing pasireotide to be continued.
B) Discontinue pasireotide immediately, because any treatment-emergent hyperglycemia indicates the drug cannot be safely continued, and substitute a steroidogenesis inhibitor.
C) Start a thiazolidinedione such as pioglitazone as first-line therapy, because pasireotide-induced hyperglycemia is driven primarily by peripheral insulin resistance that insulin sensitizers directly reverse.
D) Start a sulfonylurea such as glyburide as first-line therapy, because forcing maximal insulin secretion fully overcomes the somatostatin receptor-mediated suppression caused by pasireotide.
E) Make no change and simply continue monitoring, because pasireotide-induced hyperglycemia is self-limited and resolves without pharmacological treatment in nearly all patients.
ANSWER: A
Rationale:
Pasireotide-induced hyperglycemia is common and results chiefly from somatostatin receptor-mediated suppression of pancreatic insulin secretion, along with impaired incretin and glucagon regulation. When the drug is providing meaningful cortisol control, as it is here, the appropriate approach is to manage the hyperglycemia pharmacologically rather than abandon effective therapy. GLP-1 receptor agonists are the preferred first-line agents because they stimulate insulin secretion and suppress glucagon through GLP-1 receptor signaling that remains effective despite somatostatin receptor activation, directly countering the mechanism of pasireotide-induced hyperglycemia. This allows pasireotide to be continued while glucose is controlled.
Option B: Option B is incorrect because treatment-emergent hyperglycemia does not require immediate discontinuation of an otherwise effective pasireotide regimen; the hyperglycemia is anticipated and managed pharmacologically.
Option C: Option C is incorrect because the primary driver of pasireotide-induced hyperglycemia is impaired insulin secretion rather than peripheral insulin resistance, so thiazolidinediones do not address the central defect and are not first-line.
Option D: Option D is incorrect because sulfonylurea-stimulated insulin release is partially blunted by concurrent somatostatin receptor activation, making sulfonylureas less effective than GLP-1 receptor agonists in this setting.
Option E: Option E is incorrect because pasireotide-induced hyperglycemia is common and often requires active pharmacological management rather than resolving spontaneously; leaving an HbA1c of 7.9% untreated would be inappropriate.
7. A 44-year-old woman with Cushing disease has been on metyrapone for 5 weeks. Her urinary free cortisol (UFC) has fallen appropriately and her cushingoid features are beginning to improve. However, she now has a blood pressure of 158/96 mmHg (previously 138/84) and a serum potassium of 3.0 mEq/L. She feels well overall. Which of the following best explains these new findings and the most appropriate management?
A) The hypertension and hypokalemia indicate metyrapone treatment failure with worsening cortisol excess, so metyrapone should be stopped and replaced with a different agent.
B) The findings indicate adrenal insufficiency from over-suppression of cortisol, so metyrapone should be held and hydrocortisone administered.
C) The hypertension and hypokalemia reflect pasireotide-type hyperglycemia complications, so glucose and HbA1c should be checked and an antidiabetic agent started.
D) The findings reflect accumulation of 11-deoxycorticosterone (DOC), a weak mineralocorticoid that builds up because metyrapone's CYP11B1 block prevents its conversion to corticosterone while rising ACTH drives more precursor through the pathway; DOC-mediated mineralocorticoid excess produces hypertension and hypokalemia even as UFC falls — so metyrapone can be continued for its cortisol-lowering benefit while the blood pressure and potassium are managed (for example, with a mineralocorticoid receptor antagonist and potassium repletion).
E) The findings indicate cabergoline-induced valvulopathy producing heart failure and secondary hyperaldosteronism, so an echocardiogram should be obtained and cabergoline discontinued.
ANSWER: D
Rationale:
This vignette presents the characteristic pattern of metyrapone-associated mineralocorticoid excess. Metyrapone inhibits CYP11B1 (11-beta-hydroxylase), which blocks not only conversion of 11-deoxycortisol to cortisol but also conversion of 11-deoxycorticosterone (DOC) to corticosterone. DOC therefore accumulates, and the rising ACTH that accompanies falling cortisol drives still more precursor into the pathway, increasing DOC further. DOC is a weak mineralocorticoid; in excess it activates renal mineralocorticoid receptors, causing sodium retention (hypertension) and potassium wasting (hypokalemia) — and this occurs precisely when the drug is working, as shown by the falling UFC and improving cushingoid features. Because the drug is effective, it can be continued for cortisol control while the mineralocorticoid effects are managed, for example with a mineralocorticoid receptor antagonist and potassium repletion.
Option A: Option A is incorrect because the hypertension and hypokalemia occur alongside a falling UFC and clinical improvement, indicating the drug is working rather than failing; the findings are due to DOC accumulation, not worsening cortisol excess.
Option B: Option B is incorrect because the pattern of hypertension with hypokalemia is the opposite of adrenal insufficiency, which causes hypotension and hyponatremia; this is mineralocorticoid excess, not cortisol over-suppression.
Option C: Option C is incorrect because the findings are not related to pasireotide or hyperglycemia; the patient is on metyrapone, and hypertension with hypokalemia reflects DOC-mediated mineralocorticoid excess, not a glucose complication.
Option E: Option E is incorrect because the patient is on metyrapone, not cabergoline, and the findings are explained by DOC accumulation rather than valvulopathy-induced heart failure; there is no indication of cardiac valve disease in this scenario.
8. A 57-year-old man with a kidney transplant maintained on tacrolimus develops Cushing disease that persists after pituitary surgery. The team plans medical cortisol-lowering therapy. They are concerned about drug interactions with his immunosuppression. Which of the following best describes the most important interaction consideration and the most appropriate management approach?
A) Ketoconazole is the preferred agent in transplant patients because its CYP3A4 inhibition raises tacrolimus levels, allowing the tacrolimus dose to be lowered and reducing immunosuppression costs without additional monitoring.
B) Ketoconazole is a strong CYP3A4 inhibitor and tacrolimus is a CYP3A4 substrate, so co-administration would markedly increase tacrolimus levels and the risk of nephrotoxicity and neurotoxicity; therefore, if ketoconazole is used it requires substantial tacrolimus dose reduction with frequent trough monitoring, and an agent with fewer CYP3A4 interactions (such as metyrapone or osilodrostat) may be preferable for cortisol control in this patient.
C) Tacrolimus and ketoconazole have no clinically meaningful interaction because tacrolimus is eliminated unchanged by the kidney, so no dose adjustment or monitoring is needed.
D) Mitotane is the preferred agent because it inhibits CYP3A4 and stabilizes tacrolimus levels, simplifying immunosuppression management in transplant patients.
E) The only relevant concern is additive nephrotoxicity between tacrolimus and cabergoline, so renal function should be monitored, but no cytochrome-based interaction exists with any cortisol-lowering agent.
ANSWER: B
Rationale:
The critical interaction in this transplant patient is between ketoconazole and tacrolimus. Ketoconazole is a strong inhibitor of CYP3A4, the principal enzyme responsible for tacrolimus metabolism, so co-administration dramatically increases tacrolimus concentrations and the risk of tacrolimus toxicity — nephrotoxicity and neurotoxicity — at previously stable doses. If ketoconazole is used, it requires substantial tacrolimus dose reduction (often 50% or more) with frequent trough monitoring; alternatively, a cortisol-lowering agent with fewer CYP3A4 interactions, such as metyrapone or osilodrostat, may be preferable for this patient to avoid destabilizing the immunosuppression. This is the central clinical-reasoning point: anticipate the CYP3A4 interaction and either monitor intensively or choose a less-interacting agent.
Option A: Option A is incorrect because deliberately exploiting ketoconazole's CYP3A4 inhibition to lower tacrolimus dosing is unsafe and not standard; the interaction is unpredictable and dangerous, requires intensive monitoring rather than no monitoring, and is not a cost-saving strategy.
Option C: Option C is incorrect because tacrolimus is extensively metabolized by hepatic CYP3A4, not eliminated unchanged renally, so there is a major, clinically significant interaction with ketoconazole that mandates dose adjustment and monitoring.
Option D: Option D is incorrect because mitotane induces rather than inhibits CYP3A4, which would lower tacrolimus levels and risk rejection rather than stabilize them; mitotane is reserved chiefly for adrenocortical carcinoma and is not a convenient agent for this setting.
Option E: Option E is incorrect because the dominant concern is the CYP3A4-mediated interaction between ketoconazole and tacrolimus; cytochrome-based interactions clearly do exist with cortisol-lowering agents, so dismissing them is incorrect.
9. A 59-year-old woman with Cushing syndrome and difficult-to-control type 2 diabetes was started on mifepristone 8 weeks ago. Her fasting glucose has fallen from 220 to 110 mg/dL, her blood pressure has improved, and she has lost 7 kg. Laboratory testing now shows a markedly elevated serum cortisol and an elevated urinary free cortisol (UFC). A covering physician, alarmed by the high cortisol, recommends adding ketoconazole to bring the cortisol down. Which of the following is the most appropriate interpretation and management?
A) The elevated cortisol confirms treatment failure; add ketoconazole to lower cortisol production, since mifepristone is clearly not controlling the disease.
B) The elevated cortisol indicates that mifepristone has caused a paradoxical worsening of hypercortisolism; discontinue mifepristone and pursue urgent bilateral adrenalectomy.
C) The elevated cortisol and UFC are the expected pharmacodynamic consequence of mifepristone — a glucocorticoid receptor antagonist that does not lower cortisol secretion and removes negative feedback, so cortisol and ACTH rise — and these markers cannot be used to judge efficacy; her marked clinical and metabolic improvement (glucose, blood pressure, weight) confirms the drug is working, so mifepristone should be continued and ketoconazole should not be added, as combining it would substantially increase the risk of adrenal insufficiency.
D) The elevated cortisol indicates impending adrenal crisis; administer high-dose hydrocortisone and obtain a cosyntropin stimulation test to confirm adrenal insufficiency before continuing.
E) The elevated UFC means the mifepristone dose is too low; double the dose to suppress cortisol secretion more effectively and recheck UFC in 2 weeks.
ANSWER: C
Rationale:
This vignette tests the clinician's ability to correctly interpret rising cortisol during mifepristone therapy. Mifepristone is a glucocorticoid receptor (GR) antagonist that blocks cortisol action at target tissues without reducing cortisol secretion; because GR blockade removes negative feedback on the hypothalamic-pituitary axis, ACTH and cortisol rise during therapy. Serum cortisol and UFC are therefore uninterpretable as efficacy markers. The patient's marked clinical and metabolic improvement — glucose normalization, improved blood pressure, and 7 kg weight loss — confirms the drug is working as intended. Mifepristone should be continued, and ketoconazole should not be added: combining a steroidogenesis inhibitor with GR blockade would substantially increase the risk of adrenal insufficiency, and there is no need to "treat" a laboratory value that is expected to rise.
Option A: Option A is incorrect because the elevated cortisol does not indicate treatment failure; it is the predictable result of GR blockade, and the clinical improvement demonstrates efficacy, so adding ketoconazole is both unnecessary and hazardous.
Option B: Option B is incorrect because mifepristone does not cause paradoxical worsening of disease; the rising cortisol is an expected pharmacodynamic effect, and there is no indication for urgent bilateral adrenalectomy in a patient who is improving clinically.
Option D: Option D is incorrect because there is no evidence of adrenal crisis — the patient is improving, not deteriorating — and the cosyntropin stimulation test is not a reliable way to assess adrenal insufficiency during GR blockade; adrenal insufficiency on mifepristone is diagnosed clinically.
Option E: Option E is incorrect because the elevated UFC does not indicate an inadequate dose; UFC rises as an expected consequence of GR blockade and cannot be used to titrate the dose, which is instead guided by clinical and metabolic endpoints.
10. A 46-year-old woman underwent bilateral adrenalectomy for refractory Cushing disease 3 years ago and has been maintained on hydrocortisone and fludrocortisone. She now presents with progressive darkening of her skin and oral mucosa, new headaches, and early visual field changes. Serum adrenocorticotropic hormone (ACTH) is markedly elevated at 720 pg/mL, and MRI shows an enlarging invasive sellar mass. Which of the following is the correct diagnosis and the most appropriate management approach?
A) Primary adrenal insufficiency with inadequate replacement; increase her hydrocortisone and fludrocortisone doses, as the hyperpigmentation reflects undertreatment and the sellar mass is incidental.
B) Recurrent Cushing syndrome from an ectopic ACTH-secreting tumor; obtain chest and abdominal imaging to localize the ectopic source and resect it.
C) A nonfunctioning pituitary macroadenoma causing hypopituitarism; the elevated ACTH is a laboratory artifact, and the mass should simply be observed with serial imaging.
D) Pituitary apoplexy of a pre-existing adenoma; provide stress-dose glucocorticoids and obtain urgent neurosurgical evaluation for acute decompression.
E) Nelson syndrome — an aggressive, invasive ACTH-secreting corticotroph adenoma that develops after bilateral adrenalectomy because the loss of cortisol negative feedback drives unopposed ACTH hypersecretion and tumor growth; management includes transsphenoidal surgery and/or radiotherapy for the tumor, with medical options such as pasireotide or cabergoline to suppress ACTH, and the hyperpigmentation is explained by ACTH-driven melanocyte stimulation.
ANSWER: E
Rationale:
This is a classic presentation of Nelson syndrome: an aggressive, invasive ACTH-secreting corticotroph adenoma that develops after bilateral adrenalectomy performed for refractory Cushing disease. With the adrenal glands removed, cortisol production ceases and the negative feedback that normally restrains ACTH secretion and limits corticotroph tumor growth is permanently lost, driving unopposed ACTH hypersecretion (here, 720 pg/mL) and accelerated, often invasive tumor growth producing headache and visual compromise. The striking hyperpigmentation of skin and mucosa is a hallmark, explained by ACTH's structural homology with melanocyte-stimulating hormone and consequent melanocortin receptor activation. Management includes transsphenoidal surgery and/or radiotherapy for the tumor, with medical therapy such as pasireotide (via SSTR5) or cabergoline (via D2R) to help suppress ACTH.
Option A: Option A is incorrect because the hyperpigmentation and markedly elevated ACTH with an enlarging invasive sellar mass point to corticotroph tumor growth, not simply inadequate steroid replacement; the mass is not incidental, and increasing replacement would not address the tumor.
Option B: Option B is incorrect because the ACTH source is the pituitary corticotroph adenoma driven by lost feedback after adrenalectomy, not an ectopic tumor; the enlarging sellar mass localizes the source to the pituitary.
Option C: Option C is incorrect because the markedly elevated ACTH is genuine and central to the diagnosis, not an artifact, and the mass is a functioning, growing corticotroph adenoma that requires active management rather than observation.
Option D: Option D is incorrect because the clinical course is progressive tumor growth with sustained ACTH hypersecretion over years, not the abrupt presentation of pituitary apoplexy from acute infarction; the gradual hyperpigmentation and slowly progressive visual changes are inconsistent with apoplexy.
11. A 63-year-old man with adrenocortical carcinoma was started on mitotane 4 weeks ago. He takes warfarin for chronic atrial fibrillation and also requires glucocorticoid and mineralocorticoid replacement. At this visit, his international normalized ratio (INR) has fallen from a therapeutic 2.4 to 1.3 despite no change in warfarin dose, and he reports increasing fatigue and light-headedness. Which of the following best explains these findings and the most appropriate management?
A) Mitotane has inhibited CYP2C9, raising warfarin levels and the INR; reduce the warfarin dose to prevent bleeding, and reduce the glucocorticoid replacement dose because mitotane raises endogenous cortisol.
B) The falling INR reflects dietary vitamin K changes unrelated to mitotane; counsel on diet and recheck INR, and attribute the fatigue to deconditioning rather than any drug effect.
C) Mitotane displaces warfarin from adipose stores, transiently raising the INR; hold warfarin for several days and continue current replacement steroid doses unchanged.
D) Mitotane is a potent inducer of CYP3A4 and CYP2B6 (and induces CYP2C9), accelerating warfarin metabolism and lowering the INR — so the warfarin dose must be increased substantially with frequent INR monitoring; the same enzyme induction accelerates corticosteroid metabolism and, together with mitotane-induced adrenal destruction, means his glucocorticoid (and often mineralocorticoid) replacement doses must be increased to relieve the fatigue and light-headedness of inadequate replacement.
E) The findings indicate mitotane overdose causing both bleeding and adrenal crisis; stop mitotane permanently, reverse anticoagulation, and avoid all further adrenal-directed therapy.
ANSWER: D
Rationale:
This vignette integrates mitotane's enzyme-induction profile with its adrenolytic effect in a single patient. Mitotane is a potent inducer of CYP3A4 and CYP2B6 and also induces CYP2C9; warfarin is metabolized by CYP2C9 (S-enantiomer) and CYP3A4 (R-enantiomer), so mitotane accelerates warfarin clearance, lowers warfarin exposure, and drops the INR — here from 2.4 to 1.3. The correct response is to increase the warfarin dose substantially with frequent INR monitoring (every 2 weeks) until a new stable therapeutic INR is reached, which is especially important given the thrombotic risk of atrial fibrillation. Simultaneously, the same enzyme induction accelerates corticosteroid metabolism, and mitotane's adrenal destruction abolishes endogenous steroid production; together these explain his fatigue and light-headedness as inadequate replacement, so his glucocorticoid (and often mineralocorticoid) replacement doses must be increased — frequently doubled or tripled — to maintain adequate levels.
Option A: Option A is incorrect because mitotane induces rather than inhibits CYP2C9, so the INR falls rather than rises and warfarin must be increased; mitotane also lowers, not raises, endogenous cortisol (via adrenal destruction), so glucocorticoid replacement must increase, not decrease.
Option B: Option B is incorrect because the marked INR fall coincides with mitotane initiation and is explained by enzyme induction, not diet; and the fatigue and light-headedness reflect inadequate glucocorticoid replacement from accelerated steroid metabolism and adrenal destruction, not deconditioning.
Option C: Option C is incorrect because mitotane lowers the INR through enzyme induction rather than raising it via adipose displacement, so holding warfarin would worsen sub-therapeutic anticoagulation, and the replacement steroid doses need to increase rather than stay unchanged.
Option E: Option E is incorrect because the picture is not mitotane overdose causing bleeding and crisis; the INR is low (sub-therapeutic, raising thrombotic not bleeding risk), and mitotane is the indicated therapy for adrenocortical carcinoma, so it should be continued with appropriate dose adjustments rather than permanently stopped.
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