1. Aldosterone produces its principal effect on renal sodium handling by binding the mineralocorticoid receptor (MR) in the distal nephron and collecting duct, where the activated receptor acts as a transcription factor. Which of the following best describes the immediate genomic consequence of MR activation in these cells?
A) Inhibition of the epithelial sodium channel (ENaC), promoting sodium loss into the urine
B) Direct phosphorylation of membrane sodium channels without any change in gene transcription
C) Increased transcription of ENaC subunits and the Na/K-ATPase (sodium-potassium adenosine triphosphatase), enhancing sodium reabsorption with potassium secretion
D) Suppression of Na/K-ATPase synthesis, reducing the basolateral sodium gradient
E) Upregulation of aquaporin water channels as the primary and sole mechanism of volume expansion
ANSWER: C
Rationale:
Option C is correct. Aldosterone binds MR in aldosterone-sensitive distal nephron cells; the ligand-receptor complex translocates to the nucleus, binds mineralocorticoid response elements, and drives transcription of the three ENaC (epithelial sodium channel) subunits and the basolateral Na/K-ATPase (sodium-potassium adenosine triphosphatase). The resulting electrochemical gradient drives sodium reabsorption with potassium secreted into the lumen as the counterion, expanding extracellular fluid volume and raising blood pressure.
Option A: Option A is incorrect because MR activation increases, rather than inhibits, ENaC activity; ENaC inhibition is the mechanism of amiloride, not aldosterone.
Option B: Option B is incorrect because the principal renal effect is genomic (transcriptional). Although rapid non-genomic membrane-associated MR signaling exists, it modulates channel trafficking and does not replace the transcriptional induction of ENaC and Na/K-ATPase that constitutes the dominant sodium-retaining mechanism.
Option D: Option D is incorrect because MR activation increases Na/K-ATPase expression and activity; suppressing it would impair, not enhance, sodium reabsorption.
Option E: Option E is incorrect because the sodium-retaining action drives secondary water retention; aquaporin upregulation is principally a vasopressin-mediated effect and is not the primary mechanism of aldosterone-driven volume expansion.
2. Cortisol circulates at concentrations 100- to 1000-fold higher than aldosterone and binds the mineralocorticoid receptor (MR) with affinity equal to or greater than aldosterone. Despite this, aldosterone normally retains selective control of renal MR. Which mechanism explains this selectivity?
A) The enzyme 11beta-HSD2 (11-beta-hydroxysteroid dehydrogenase type 2), co-expressed with MR in the distal nephron, converts cortisol to inactive cortisone before it can activate the receptor
B) Cortisol is unable to cross the cell membrane of distal nephron cells, so it never reaches intracellular MR
C) Aldosterone binds MR irreversibly, permanently excluding cortisol from the binding site
D) Circulating cortisol is fully bound to corticosteroid-binding globulin and therefore has no free fraction available to MR
E) MR in the kidney has a structurally distinct binding pocket that physically excludes cortisol
ANSWER: A
Rationale:
Option A is correct. 11beta-HSD2 (11-beta-hydroxysteroid dehydrogenase type 2) is co-expressed with MR in aldosterone-sensitive distal nephron cells and rapidly oxidizes cortisol to cortisone, which has negligible MR affinity. Aldosterone is not a substrate for this enzyme, so it survives within this protected compartment to selectively activate MR. When 11beta-HSD2 is inhibited or overwhelmed, cortisol activates MR and produces apparent mineralocorticoid excess.
Option B: Option B is incorrect because cortisol, a lipophilic steroid, readily crosses cell membranes and does reach intracellular MR; selectivity comes from enzymatic inactivation, not exclusion from the cytoplasm.
Option C: Option C is incorrect because MR binding is reversible and competitive; aldosterone does not irreversibly occupy the receptor.
Option D: Option D is incorrect because although most cortisol is protein-bound, the free fraction is more than sufficient to activate MR; the protective mechanism is local enzymatic conversion, not the absence of free hormone.
Option E: Option E is incorrect because renal MR binds cortisol with high affinity; there is no structural exclusion of cortisol, which is precisely why the enzymatic guard is required.
3. A patient with primary adrenal insufficiency (AI) requires replacement of the hormone normally produced by the zona glomerulosa. Which agent is used to provide oral mineralocorticoid replacement in this setting?
A) Hydrocortisone, titrated upward until mineralocorticoid effects appear
B) Spironolactone at low dose
C) Dexamethasone given once daily at bedtime
D) Fludrocortisone acetate, an orally active synthetic mineralocorticoid
E) Eplerenone twice daily
ANSWER: D
Rationale:
Option D is correct. Fludrocortisone acetate is a synthetic fluorinated mineralocorticoid with roughly 125-fold greater mineralocorticoid potency than hydrocortisone and is the only oral mineralocorticoid replacement agent in clinical use. In primary AI, aldosterone deficiency causes sodium wasting, hypovolemia, hyperkalemia, and hypotension; fludrocortisone 50 to 200 micrograms per day, titrated to plasma renin activity, normal electrolytes, and absence of postural hypotension, corrects this deficit.
Option A: Option A is incorrect because while hydrocortisone has some intrinsic mineralocorticoid activity, the doses required to achieve adequate mineralocorticoid replacement would produce glucocorticoid excess; a dedicated mineralocorticoid is used instead.
Option B: Option B is incorrect because spironolactone is an MR antagonist; it would block, not replace, mineralocorticoid action and would worsen the sodium wasting and hyperkalemia of primary AI.
Option C: Option C is incorrect because dexamethasone is a potent glucocorticoid with essentially no mineralocorticoid activity and cannot replace aldosterone.
Option E: Option E is incorrect because eplerenone is a selective MR antagonist; like spironolactone, it opposes rather than supplies mineralocorticoid action.
4. A man treated with spironolactone for heart failure develops gynecomastia and decreased libido. These off-target effects are best explained by spironolactone's activity at which receptor?
A) The glucocorticoid receptor (GR), producing Cushingoid features
B) The androgen receptor (AR), which spironolactone antagonizes
C) The beta-adrenergic receptor, producing endocrine disruption
D) The estrogen receptor, which spironolactone directly activates
E) The mineralocorticoid receptor (MR) alone, with no other receptor involvement
ANSWER: B
Rationale:
Option B is correct. Spironolactone is a steroidal MR antagonist whose structural similarity to steroid hormones produces clinically important cross-reactivity. It antagonizes the androgen receptor (AR), causing gynecomastia, decreased libido, and erectile dysfunction in men and menstrual irregularities in women, particularly at doses above 50 to 100 mg per day. This anti-androgen effect is also exploited therapeutically for acne and hirsutism in women.
Option A: Option A is incorrect because, although spironolactone has weak interactions with several steroid receptors, gynecomastia and sexual dysfunction arise from AR antagonism, not glucocorticoid-receptor agonism; it does not produce Cushingoid features.
Option C: Option C is incorrect because spironolactone has no meaningful beta-adrenergic activity.
Option D: Option D is incorrect because spironolactone does not directly activate the estrogen receptor; the feminizing effects derive from androgen-receptor blockade and weak progestogenic activity, not estrogen-receptor agonism.
Option E: Option E is incorrect because the off-target endocrine effects are precisely the point: spironolactone acts beyond MR, and that lack of selectivity distinguishes it from eplerenone.
5. A clinician wishes to provide mineralocorticoid receptor (MR) blockade in a man with heart failure but wants to avoid the gynecomastia and sexual side effects associated with spironolactone. Which agent best meets this goal, and why?
A) Fludrocortisone, because it blocks MR without androgen-receptor activity
B) Finerenone, because it is a steroidal agent with strong androgen-receptor antagonism
C) Higher-dose spironolactone, because the off-target effects diminish at higher doses
D) Dexamethasone, because it blocks MR selectively
E) Eplerenone, because it is a selective MR antagonist with negligible affinity for the androgen, progesterone, and glucocorticoid receptors
ANSWER: E
Rationale:
Option E is correct. Eplerenone is a steroidal MR antagonist engineered for selectivity: it has negligible affinity for the androgen receptor (AR), progesterone receptor (PR), and glucocorticoid receptor (GR). It therefore delivers MR blockade without the gynecomastia, sexual dysfunction, or menstrual irregularities seen with spironolactone, at the cost of roughly 60-fold lower MR potency (requiring twice-daily dosing) and higher cost.
Option A: Option A is incorrect because fludrocortisone is an MR agonist, not an antagonist; it would supply mineralocorticoid action rather than block it.
Option B: Option B is incorrect because finerenone is a non-steroidal MR antagonist with high selectivity and no meaningful androgen-receptor antagonism; the description misstates both its chemistry and its receptor profile.
Option C: Option C is incorrect because spironolactone's anti-androgen effects increase, not decrease, with dose; raising the dose worsens gynecomastia.
Option D: Option D is incorrect because dexamethasone is a glucocorticoid agonist with no MR-antagonist activity.
6. Which single biochemical finding most directly distinguishes primary adrenal insufficiency (AI) from secondary AI?
A) Plasma ACTH (adrenocorticotropic hormone) is elevated in primary AI and low or inappropriately normal in secondary AI
B) Serum cortisol is low in primary AI but normal in secondary AI
C) Plasma ACTH is low in primary AI and elevated in secondary AI
D) Serum glucose is elevated in primary AI and low in secondary AI
E) Plasma renin activity is suppressed in both forms equally
ANSWER: A
Rationale:
Option A is correct. In primary AI the adrenal cortex is destroyed, so loss of cortisol negative feedback drives compensatory ACTH (adrenocorticotropic hormone) hypersecretion, raising plasma ACTH. In secondary AI the lesion is at the pituitary, so ACTH is low or inappropriately normal. This difference, together with the presence of mineralocorticoid-deficiency features (hyperkalemia, hyponatremia, postural hypotension) in primary AI, defines the distinction.
Option B: Option B is incorrect because cortisol is low in both primary and secondary AI; a low cortisol does not by itself separate the two.
Option C: Option C inverts the correct relationship: ACTH is high in primary AI and low in secondary AI, not the reverse.
Option D: Option D is incorrect because hypoglycemia, when present, reflects glucocorticoid deficiency common to both forms and does not distinguish them.
Option E: Option E is incorrect because plasma renin activity is characteristically elevated in primary AI (aldosterone deficiency) and normal in secondary AI, so it is not suppressed equally in both.
7. A patient with secondary adrenal insufficiency (AI) due to a pituitary tumor is started on hydrocortisone. The clinician considers whether fludrocortisone is also needed. Which statement is correct?
A) Fludrocortisone is required in secondary AI because the zona glomerulosa is destroyed
B) Fludrocortisone is required in all forms of AI regardless of cause
C) Fludrocortisone is generally not required in secondary AI because the zona glomerulosa remains responsive to the renin-angiotensin-aldosterone system
D) Fludrocortisone is contraindicated in any form of AI
E) Fludrocortisone must replace hydrocortisone entirely in secondary AI
ANSWER: C
Rationale:
Option C is correct. In secondary (and tertiary) AI the defect is pituitary or hypothalamic, so ACTH-dependent cortisol production fails, but the zona glomerulosa remains intact and responsive to the renin-angiotensin-aldosterone system (RAAS). Because aldosterone secretion is preserved, mineralocorticoid replacement is generally unnecessary; glucocorticoid replacement alone suffices.
Option A: Option A is incorrect because the zona glomerulosa is not destroyed in secondary AI; the pituitary, not the adrenal cortex, is the site of failure.
Option B: Option B is incorrect because mineralocorticoid replacement is required only in primary AI, where the zona glomerulosa is destroyed; it is not needed in every form.
Option D: Option D is incorrect because fludrocortisone is not contraindicated in AI; it is essential in primary AI.
Option E: Option E is incorrect because fludrocortisone, a mineralocorticoid, cannot substitute for glucocorticoid replacement; hydrocortisone remains necessary.
8. Hydrocortisone is the preferred glucocorticoid for routine replacement in adrenal insufficiency (AI). Which property most accounts for this preference?
A) Its very long half-life allows convenient once-weekly dosing
B) It is identical to endogenous cortisol and has a relatively short half-life, allowing divided dosing that mimics the physiological diurnal rhythm
C) It has the highest mineralocorticoid potency of available glucocorticoids, eliminating the need for fludrocortisone
D) It cannot be absorbed orally, ensuring steady intravenous delivery
E) It has no glucocorticoid receptor activity, avoiding suppression of the axis
ANSWER: B
Rationale:
Option B is correct. Hydrocortisone is chemically identical to endogenous cortisol and has a relatively short half-life of about 1.5 hours. Given in divided doses (largest on waking, smaller doses later in the day but not at bedtime), it approximates the physiological diurnal cortisol curve and avoids the prolonged axis suppression caused by longer-acting synthetic glucocorticoids.
Option A: Option A is incorrect because hydrocortisone's short half-life is precisely what makes once-weekly dosing impossible; it requires divided daily dosing.
Option C: Option C is incorrect because hydrocortisone's mineralocorticoid potency is low relative to fludrocortisone; in primary AI a dedicated mineralocorticoid is still required.
Option D: Option D is incorrect because hydrocortisone is well absorbed orally and is routinely given by mouth for maintenance replacement.
Option E: Option E is incorrect because hydrocortisone is a full glucocorticoid receptor agonist; that agonism is exactly what provides the needed replacement.
9. Metyrapone is used to control severe hypercortisolism. Which enzymatic step does it inhibit?
A) CYP11A1 (cholesterol side-chain cleavage), the first committed step of steroidogenesis
B) Aldosterone synthase (CYP11B2) selectively, with no effect on cortisol synthesis
C) 5-alpha-reductase, blocking conversion of testosterone to dihydrotestosterone
D) CYP11B1 (11-beta-hydroxylase), the final step converting 11-deoxycortisol to cortisol
E) Aromatase, blocking estrogen synthesis
ANSWER: D
Rationale:
Option D is correct. Metyrapone inhibits CYP11B1 (11-beta-hydroxylase), the enzyme that catalyzes the final step of cortisol synthesis, the conversion of 11-deoxycortisol to cortisol. Blockade lowers cortisol within hours, making metyrapone one of the fastest-acting agents for severe hypercortisolism. The accumulating 11-deoxycortisol serves as a marker of drug effect, while shunting of precursors raises adrenal androgens and the mineralocorticoid precursor deoxycorticosterone.
Option A: Option A is incorrect because CYP11A1 (side-chain cleavage) is inhibited by agents such as mitotane and ketoconazole, not by metyrapone, whose action is at the terminal 11-hydroxylation step.
Option B: Option B is incorrect because metyrapone's principal target is the cortisol-synthesizing CYP11B1; it is not a selective aldosterone-synthase inhibitor.
Option C: Option C is incorrect because 5-alpha-reductase is unrelated to corticosteroid synthesis and is the target of finasteride.
Option E: Option E is incorrect because aromatase inhibition blocks estrogen synthesis and is irrelevant to metyrapone's mechanism.
10. A patient on high-dose glucocorticoid therapy develops sodium retention, edema, hypertension, and hypokalemia. How does a high pharmacological glucocorticoid load produce these mineralocorticoid-like effects?
A) Glucocorticoids directly stimulate aldosterone synthase, raising aldosterone output
B) Glucocorticoids upregulate ENaC expression independently of any receptor
C) Glucocorticoids induce 11beta-HSD2, increasing conversion of cortisol to active mineralocorticoid
D) Glucocorticoids antagonize the mineralocorticoid receptor, causing paradoxical retention
E) High cortisol concentrations saturate 11beta-HSD2, so cortisol escapes inactivation and activates renal mineralocorticoid receptors
ANSWER: E
Rationale:
Option E is correct. Renal MR is normally protected from cortisol by 11beta-HSD2, which converts cortisol to inactive cortisone. At high pharmacological glucocorticoid concentrations this enzyme is saturated; cortisol then escapes inactivation, reaches and activates renal MR, and produces sodium retention, edema, hypertension, and hypokalemia, the same pattern seen in apparent mineralocorticoid excess.
Option A: Option A is incorrect because the effect does not require increased aldosterone; it results from cortisol itself activating MR, and aldosterone is typically suppressed in this setting.
Option B: Option B is incorrect because ENaC upregulation here is receptor-mediated (through MR), not receptor-independent.
Option C: Option C inverts the mechanism: saturation or inhibition of 11beta-HSD2, not its induction, allows cortisol to act at MR; induction would increase protection.
Option D: Option D is incorrect because the effect is MR agonism by cortisol, not antagonism; antagonism would cause sodium loss, not retention.
11. A patient with type 2 diabetes and diabetic kidney disease (DKD) with elevated albuminuria remains at high cardiorenal risk despite maximally tolerated renin-angiotensin-aldosterone system (RAAS) blockade. Which agent is specifically approved to reduce cardiorenal outcomes in this population?
A) Spironolactone, on the basis of the RALES heart-failure trial
B) Finerenone, a non-steroidal mineralocorticoid receptor (MR) antagonist shown to reduce cardiorenal endpoints in DKD
C) Fludrocortisone, to restore mineralocorticoid tone
D) Eplerenone, approved specifically for diabetic kidney disease
E) Dexamethasone, to reduce glomerular inflammation
ANSWER: B
Rationale:
Option B is correct. Finerenone is a non-steroidal MR antagonist with high selectivity and balanced heart-kidney tissue distribution. The FIDELIO-DKD and FIGARO-DKD trials demonstrated reduction of composite cardiorenal endpoints in patients with type 2 diabetes and DKD with elevated albuminuria already on maximally tolerated RAAS blockade, establishing it as the first MR antagonist approved specifically for this cardiorenal indication.
Option A: Option A is incorrect because spironolactone's RALES evidence is in severe heart failure, not the DKD cardiorenal-outcomes indication.
Option C: Option C is incorrect because fludrocortisone is an MR agonist and would worsen sodium retention and proteinuric kidney disease, not protect against it.
Option D: Option D is incorrect because eplerenone's outcome evidence and approvals are in heart failure and post-myocardial-infarction left ventricular dysfunction, not DKD.
Option E: Option E is incorrect because dexamethasone is a glucocorticoid without an MR-antagonist mechanism and is not used for cardiorenal protection in DKD.
12. Which adverse effect is the principal dose-limiting concern shared by all mineralocorticoid receptor (MR) antagonists, requiring routine monitoring especially in renal impairment or concurrent RAAS blockade?
A) Hyperkalemia
B) Hypokalemia
C) Hypernatremia
D) Hyperglycemia
E) Hepatotoxicity
ANSWER: A
Rationale:
Option A is correct. By blocking MR, these agents reduce renal potassium secretion, so hyperkalemia is the major dose-limiting adverse effect. Risk rises in patients with reduced eGFR (estimated glomerular filtration rate), typically below 60 mL per minute per 1.73 m2, and in those on concurrent renin-angiotensin-aldosterone system (RAAS) blockade, making serum potassium the key monitoring parameter.
Option B: Option B is incorrect because MR antagonists are potassium-sparing; they cause hyperkalemia, not hypokalemia. Hypokalemia is instead seen with MR agonism or 11beta-HSD2 inhibition.
Option C: Option C is incorrect because MR antagonism promotes natriuresis and tends to lower, not raise, serum sodium.
Option D: Option D is incorrect because hyperglycemia is not a characteristic class effect of MR antagonists; it is prominent with pasireotide.
Option E: Option E is incorrect because hepatotoxicity is the signature concern of ketoconazole, not of MR antagonists as a class.
13. In classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase (CYP21A2) deficiency, why do affected patients develop androgen excess?
A) The enzyme block directly stimulates gonadal testosterone production
B) Loss of cortisol feedback suppresses ACTH, reducing all adrenal steroid output
C) Impaired cortisol and aldosterone synthesis reduces negative feedback, driving ACTH-stimulated accumulation of precursors that are shunted into the intact adrenal androgen pathway
D) 21-hydroxylase deficiency increases aromatase activity, converting cortisol to androgens
E) The block prevents androgen synthesis, so compensatory peripheral conversion raises androgens
ANSWER: C
Rationale:
Option C is correct. In 21-hydroxylase (CYP21A2) deficiency, impaired cortisol and aldosterone synthesis reduces negative feedback on the hypothalamic-pituitary-adrenal axis, driving ACTH (adrenocorticotropic hormone) hypersecretion and adrenocortical hyperplasia. Excess ACTH causes accumulation of precursors proximal to the block, especially 17-hydroxyprogesterone, which are shunted through the intact androgen-synthesis pathway to produce excess DHEA (dehydroepiandrosterone) and androstenedione.
Option A: Option A is incorrect because the androgen excess is adrenal in origin from precursor shunting, not direct gonadal stimulation by the enzyme defect.
Option B: Option B inverts the physiology: cortisol deficiency removes feedback and raises ACTH; it does not suppress it, and adrenal output of androgens rises rather than falls.
Option D: Option D is incorrect because aromatase converts androgens to estrogens and is not induced by 21-hydroxylase deficiency; cortisol is not a substrate for aromatase.
Option E: Option E is incorrect because the block lies in the cortisol and aldosterone pathways, leaving androgen synthesis intact; precursors are actively diverted into androgens rather than androgen synthesis being prevented.
14. What is the pharmacological rationale for glucocorticoid therapy in congenital adrenal hyperplasia (CAH)?
A) To raise serum cortisol to supraphysiological levels as the therapeutic goal
B) To directly block peripheral androgen receptors
C) To stimulate ACTH secretion and thereby normalize precursor levels
D) To suppress ACTH (adrenocorticotropic hormone) output, reducing the drive to overproduce adrenal androgen precursors
E) To inhibit 21-hydroxylase further and halt steroidogenesis entirely
ANSWER: D
Rationale:
Option D is correct. Exogenous glucocorticoid provides the negative feedback that the patient's own cortisol cannot, suppressing pituitary ACTH (adrenocorticotropic hormone) output. Lower ACTH reduces the drive that causes accumulation and shunting of androgen precursors. The therapeutic aim is to use the smallest dose that adequately suppresses precursors while preserving growth, not to normalize cortisol.
Option A: Option A is incorrect because the goal is physiological suppression of precursor overproduction, not supraphysiological cortisol; excess glucocorticoid impairs growth and causes Cushingoid effects.
Option B: Option B is incorrect because the mechanism is central ACTH suppression, not peripheral androgen-receptor blockade (the latter describes anti-androgens such as spironolactone).
Option C: Option C is incorrect because therapy suppresses ACTH; stimulating ACTH would worsen precursor accumulation.
Option E: Option E is incorrect because glucocorticoids do not inhibit 21-hydroxylase, and halting steroidogenesis is neither the mechanism nor the goal.
15. Mifepristone is used for hyperglycemia associated with endogenous Cushing syndrome. Why are plasma cortisol and urinary free cortisol (UFC) unreliable for monitoring response to this drug?
A) Mifepristone blocks the glucocorticoid receptor (GR) rather than lowering cortisol production, so cortisol and ACTH rise as feedback is removed, making cortisol-based measures uninformative
B) Mifepristone destroys the adrenal cortex, abolishing measurable cortisol
C) Mifepristone inhibits CYP11B1, so cortisol falls to undetectable levels
D) Mifepristone prevents urinary excretion of cortisol, falsely lowering UFC
E) Mifepristone converts cortisol to cortisone in the circulation
ANSWER: A
Rationale:
Option A is correct. Mifepristone is a competitive antagonist at the glucocorticoid receptor (GR); it blocks cortisol action at target tissues rather than reducing cortisol synthesis. Because GR also mediates negative feedback at the pituitary and hypothalamus, blocking it removes feedback and raises plasma cortisol and ACTH (adrenocorticotropic hormone). Consequently UFC (urinary free cortisol) and late-night salivary cortisol cannot track efficacy; clinical and glycemic parameters are the operative endpoints.
Option B: Option B is incorrect because mifepristone does not destroy the adrenal cortex; it acts at the receptor, and cortisol production continues.
Option C: Option C is incorrect because mifepristone is not a steroidogenesis inhibitor; cortisol does not fall, it rises.
Option D: Option D is incorrect because mifepristone does not block renal cortisol excretion; UFC actually rises.
Option E: Option E is incorrect because conversion of cortisol to cortisone is the function of 11beta-HSD2, not an action of mifepristone.
16. Pasireotide is a pituitary-directed agent for Cushing disease. Which pairing of mechanism and characteristic adverse effect is correct?
A) Glucocorticoid-receptor antagonism; principal adverse effect is endometrial thickening
B) CYP11B1 inhibition; principal adverse effect is hepatotoxicity
C) Mineralocorticoid-receptor antagonism; principal adverse effect is hyperkalemia
D) Adrenocorticolytic destruction; principal adverse effect is cerebellar ataxia
E) Somatostatin receptor subtype 5 (SSTR5) agonism reducing ACTH secretion; principal adverse effect is hyperglycemia
ANSWER: E
Rationale:
Option E is correct. Pasireotide is a somatostatin analog that binds several somatostatin receptor subtypes including SSTR5, which is densely expressed on corticotroph adenoma cells. Activating SSTR5 inhibits ACTH (adrenocorticotropic hormone) secretion and lowers cortisol output. Its signature adverse effect is hyperglycemia, occurring in roughly 70% of patients because somatostatin-receptor activation in pancreatic islets suppresses insulin and incretin secretion.
Option A: Option A is incorrect because glucocorticoid-receptor antagonism and endometrial thickening describe mifepristone, not pasireotide.
Option B: Option B is incorrect because CYP11B1 inhibition with hepatotoxicity points toward ketoconazole (broad steroidogenesis inhibitor), not pasireotide.
Option C: Option C is incorrect because pasireotide is not an MR antagonist; hyperkalemia is the hallmark of that class.
Option D: Option D is incorrect because adrenocorticolytic destruction with cerebellar ataxia describes mitotane, not pasireotide.
17. A patient with known adrenal insufficiency (AI) presents with severe hypotension and tachycardia refractory to fluids, hyponatremia, and altered consciousness during an acute infection. What is the correct immediate pharmacological management of this adrenal crisis?
A) Withhold steroids until a random cortisol and ACTH result confirms the diagnosis
B) Administer oral hydrocortisone and observe response over several hours
C) Give immediate intravenous (IV) hydrocortisone 100 mg as a bolus with aggressive IV normal saline, without delaying treatment for laboratory confirmation
D) Start fludrocortisone alone, as mineralocorticoid deficiency is the sole driver
E) Begin dexamethasone 0.5 mg orally once daily as initial therapy
ANSWER: C
Rationale:
Option C is correct. Adrenal crisis is life-threatening. Management is immediate IV (intravenous) hydrocortisone 100 mg as a bolus followed by 200 mg per day by infusion (or 50 mg every 6 hours), together with aggressive IV normal saline to correct the volume and sodium deficit. A random cortisol and ACTH may be drawn before the bolus if logistically possible, but treatment must never be delayed for results.
Option A: Option A is incorrect because delaying glucocorticoid to await laboratory confirmation can be fatal; empiric treatment takes priority.
Option B: Option B is incorrect because a hypotensive, vomiting, obtunded patient cannot rely on oral absorption; parenteral hydrocortisone is required, and watchful waiting is unsafe.
Option D: Option D is incorrect because the immediate need is glucocorticoid (and at stress doses hydrocortisone also provides sufficient mineralocorticoid effect); fludrocortisone alone does not treat the crisis and is not parenteral.
Option E: Option E is incorrect because oral, low-dose dexamethasone provides neither the route nor the glucocorticoid stress coverage nor the volume resuscitation the crisis demands.
18. Mineralocorticoid receptor (MR) antagonists provide benefit in heart failure and chronic kidney disease that extends beyond their diuretic and blood-pressure effects. Which mechanism best explains this added cardiorenal benefit?
A) Selective blockade of MR only in the renal collecting duct, increasing sodium excretion
B) Blockade of MR in non-epithelial tissues such as the heart and kidney, where MR activation drives fibrosis, inflammation, and adverse remodeling
C) Direct positive inotropic action on cardiac myocytes
D) Inhibition of angiotensin-converting enzyme, reducing angiotensin II
E) Stimulation of nitric oxide synthase as the sole mechanism of benefit
ANSWER: B
Rationale:
Option B is correct. MR is expressed in non-epithelial tissues including cardiac myocytes and fibroblasts, vascular smooth muscle, endothelium, and renal mesangial cells and podocytes. Activation in these sites promotes fibrosis, inflammation, oxidative stress, and proteinuria independent of sodium handling. Blocking non-epithelial MR therefore reduces adverse remodeling, which accounts for the mortality and renal-protective benefits seen with these agents beyond diuresis.
Option A: Option A is incorrect because the extra benefit derives precisely from non-epithelial MR blockade; confining the effect to the collecting duct would capture only the diuretic action.
Option C: Option C is incorrect because MR antagonists are not direct inotropes; their benefit is antifibrotic and anti-remodeling, not contractile.
Option D: Option D is incorrect because MR antagonists do not inhibit angiotensin-converting enzyme; that is the mechanism of a different drug class.
Option E: Option E is incorrect because, although improved nitric oxide bioavailability may contribute, it is not the sole mechanism; antifibrotic and anti-inflammatory effects of non-epithelial MR blockade are central.
19. A critically ill patient with florid ectopic ACTH syndrome and severe hypercortisolism cannot take oral medication and needs rapid, titratable cortisol reduction in the ICU. Which agent is uniquely suited to this situation?
A) Oral metyrapone, titrated over days
B) Oral ketoconazole, titrated to liver function
C) Subcutaneous pasireotide given twice daily
D) Etomidate by intravenous (IV) infusion at sub-anesthetic doses, which inhibits CYP11B1 and is the only parenteral agent for acute cortisol control
E) Oral mifepristone once daily
ANSWER: D
Rationale:
Option D is correct. Etomidate is an imidazole anesthetic that inhibits CYP11B1 (11-beta-hydroxylase) at sub-anesthetic IV (intravenous) infusion doses, providing rapid, titratable cortisol suppression. It is the only parenterally available agent for acute hypercortisolism and is used in the ICU for patients who cannot take oral drugs, with monitoring for sedation, respiratory depression, and emerging adrenal insufficiency.
Option A: Option A is incorrect because metyrapone, though fast-acting, is oral and unsuitable for a patient who cannot take oral medication.
Option B: Option B is incorrect because ketoconazole is oral and carries hepatotoxicity risk, and does not provide the immediate parenteral titratability required.
Option C: Option C is incorrect because pasireotide acts on pituitary corticotrophs in Cushing disease, is not parenteral in the titratable infusion sense required here, and is inappropriate for acute ectopic ACTH crisis control.
Option E: Option E is incorrect because mifepristone is oral, blocks the receptor rather than lowering cortisol, and cannot deliver rapid titratable biochemical control.
20. A patient with adrenocortical carcinoma is treated with mitotane. Why do these patients require glucocorticoid replacement at doses two to three times the usual physiological replacement dose?
A) Mitotane is adrenocorticolytic and also raises corticosteroid-binding globulin (CBG) and induces CYP3A4, lowering free cortisol and accelerating glucocorticoid metabolism
B) Mitotane blocks the glucocorticoid receptor, so higher doses are needed to overcome antagonism
C) Mitotane prevents oral absorption of glucocorticoids, requiring larger doses to compensate
D) Mitotane stimulates renal cortisol excretion, depleting body stores
E) Mitotane shortens the half-life of all drugs by inhibiting CYP3A4
ANSWER: A
Rationale:
Option A is correct. Mitotane produces selective cytotoxic destruction of adrenocortical cells (adrenocorticolytic effect) and inhibits steroidogenic enzymes, causing adrenal insufficiency that requires glucocorticoid replacement. Replacement must be supraphysiological because mitotane also increases CBG (corticosteroid-binding globulin), reducing the free cortisol fraction, and induces CYP3A4, accelerating glucocorticoid metabolism. Both effects raise the dose needed to achieve adequate free-hormone exposure.
Option B: Option B is incorrect because mitotane does not block the glucocorticoid receptor; the high requirement reflects increased binding-protein and accelerated metabolism, not receptor antagonism.
Option C: Option C is incorrect because mitotane does not impair oral glucocorticoid absorption.
Option D: Option D is incorrect because the dominant mechanisms are increased CBG and CYP3A4 induction, not stimulated renal cortisol excretion.
Option E: Option E inverts the pharmacology: mitotane induces CYP3A4 (increasing metabolism), it does not inhibit it; CYP3A4 inhibition would prolong, not shorten, drug exposure.
21. Ketoconazole is sometimes used to lower cortisol in Cushing syndrome. Which combination of properties best characterizes it?
A) Highly selective CYP11B1 inhibition with no hepatic or drug-interaction concerns
B) Mineralocorticoid-receptor antagonism with hyperkalemia as the main risk
C) Broad inhibition of multiple steroidogenic enzymes (including CYP17A1, CYP11A1, and CYP11B1) with significant hepatotoxicity risk and potent CYP3A4 inhibition causing drug interactions
D) Adrenocorticolytic destruction of the adrenal cortex like mitotane
E) Glucocorticoid-receptor antagonism with rising ACTH and cortisol
ANSWER: C
Rationale:
Option C is correct. Ketoconazole, an imidazole antifungal, inhibits several adrenal steroidogenic enzymes, including CYP17A1, CYP11A1, and CYP11B1, producing broader steroidogenesis suppression than selective CYP11B1 inhibitors. It carries a significant hepatotoxicity risk (rare acute liver failure), requiring baseline and periodic liver-function monitoring, and is a potent CYP3A4 (cytochrome P450 3A4) inhibitor that raises concentrations of many co-administered drugs.
Option A: Option A is incorrect because ketoconazole is broad, not selective, and has prominent hepatotoxicity and drug-interaction concerns.
Option B: Option B is incorrect because ketoconazole is not an MR antagonist; hyperkalemia is the hallmark of that class.
Option D: Option D is incorrect because the adrenocorticolytic destruction described is the mechanism of mitotane, not ketoconazole.
Option E: Option E is incorrect because glucocorticoid-receptor antagonism with rising ACTH and cortisol describes mifepristone, not ketoconazole.
22. A patient with adrenal insufficiency (AI) asks how to manage glucocorticoid dosing during a febrile illness. Which instruction reflects correct sick-day rules?
A) Stop hydrocortisone during illness to avoid masking infection
B) Halve the hydrocortisone dose to reduce immune suppression during infection
C) Switch to fludrocortisone alone during any febrile illness
D) Make no change, since stress does not alter glucocorticoid requirement
E) Double or triple the daily hydrocortisone dose for febrile illness, and use intramuscular (IM) or intravenous (IV) hydrocortisone 100 mg if unable to take oral medication
ANSWER: E
Rationale:
Option E is correct. Physiological stress increases glucocorticoid requirement. Sick-day rules instruct patients to double or triple the daily hydrocortisone dose during febrile illness and to use parenteral hydrocortisone 100 mg by IM (intramuscular) or IV (intravenous) route if vomiting or unable to take oral medication, preventing progression to adrenal crisis.
Option A: Option A is incorrect and dangerous because stopping glucocorticoid during the added stress of illness precipitates adrenal crisis.
Option B: Option B is incorrect because the dose must be increased, not halved; stress raises, not lowers, the requirement.
Option C: Option C is incorrect because fludrocortisone is a mineralocorticoid and cannot supply the increased glucocorticoid coverage needed during stress.
Option D: Option D is incorrect because intercurrent illness clearly increases glucocorticoid requirement; failing to up-titrate risks crisis.
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