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Module 679 lessonsCurrent endocrine guidance, Pituitary Society consensus, and US prescribing information

Cushing Syndrome

Recognize pathologic cortisol excess, confirm the biochemical pattern, localize its source, control urgent complications, and select surgery or medical therapy from the biology of the disease.

01

Separate exogenous glucocorticoid exposure, endogenous Cushing syndrome, and the pituitary-specific diagnosis of Cushing disease.

02

Choose and interpret late-night salivary cortisol, urine free cortisol, and dexamethasone suppression testing without using random cortisol as a screening test.

03

Classify confirmed hypercortisolism as ACTH dependent or ACTH independent before ordering source-directed imaging.

04

Integrate pituitary imaging, adrenal imaging, ectopic-source evaluation, and inferior petrosal sinus sampling without allowing an incidental lesion to replace biochemical reasoning.

05

Treat severe hypercortisolism as an urgent multisystem disorder and address infection, thrombosis, potassium, glucose, blood pressure, bone, and psychiatric risk.

06

Explain why cause-directed surgery is first-line for most resectable endogenous disease and how remission and recurrence are assessed.

07

Compare osilodrostat, levoketoconazole, metyrapone, and related steroidogenesis inhibitors by target, speed, monitoring, and precursor effects.

08

Compare pasireotide, cabergoline, and mifepristone by disease target, clinical endpoint, and distinctive toxicity.

09

Place radiation and bilateral adrenalectomy within a long-term plan that includes hormone replacement, tumor surveillance, recurrence testing, and recovery care.

67.01

Lesson

Recognizing Pathologic Cortisol Excess

Cushing syndrome is a pattern of sustained glucocorticoid excess. Cushing disease is the ACTH-secreting pituitary cause within that broader syndrome.

What to learn
  • Cushing syndrome
  • Cushing disease
  • Exogenous exposure
  • Discriminating features
  • Pseudo-Cushing states
Clinical signalSeparate cortisol excess from common look-alikes
01ObserveProgressive pattern

Bruising, weakness, striae, fracture, diabetes, and hypertension cluster

02ReconstructEvery glucocorticoid route

Oral, injected, inhaled, topical, ocular, and hidden products count

03NameSyndrome or disease

Pituitary ACTH defines Cushing disease within the broader syndrome

Name the syndrome correctly

Cushing syndrome includes endogenous and exogenous glucocorticoid excess. Cushing disease refers only to pituitary ACTH excess. Adrenal cortisol production and ectopic ACTH secretion are separate endogenous causes.

Use discriminating findings

Easy bruising, facial plethora, proximal muscle weakness, wide violaceous striae, unexplained osteoporosis, early hypertension or diabetes, hypokalemia, and growth failure with weight gain raise suspicion more than obesity or fatigue alone.

Exclude exposure first

A complete drug history must include oral, injected, inhaled, intranasal, topical, ocular, and unregulated products. Alcohol use disorder, depression, severe obesity, and poorly controlled diabetes can produce overlapping clinical and biochemical patterns that require careful confirmation.

Quick check

0 of 1 answered
01Which term specifically identifies pituitary ACTH-driven cortisol excess?
Answer every question to submit.
67.02

Lesson

Confirming Endogenous Hypercortisolism

Diagnosis requires validated testing of cortisol excess and loss of normal regulation, usually with repeated or complementary measurements interpreted through sleep, stress, renal function, medications, and assay limits.

What to learn
  • Late-night salivary cortisol
  • 24-hour urine free cortisol
  • One-milligram dexamethasone suppression
  • False positives
  • Cyclic disease
Biochemical proofTest excess, rhythm, and feedback
01NadirLate-night saliva

Repeated sampling tests loss of the nocturnal low point

02IntegrationUrine free cortisol

Complete collections estimate daily unbound cortisol excretion

03FeedbackDexamethasone suppression

Adequate drug exposure should suppress normal morning cortisol

Test the lost rhythm

Late-night salivary cortisol evaluates the normal midnight nadir and is often collected on two separate nights. Shift work, irregular sleep, acute stress, tobacco, contamination, and collection technique can undermine interpretation.

Measure integrated or suppressible cortisol

Twenty-four-hour urine free cortisol estimates unbound cortisol excretion and usually requires complete repeated collections. The one-milligram overnight dexamethasone test asks whether exogenous feedback suppresses morning cortisol.

Reject shortcuts

Random serum cortisol and random ACTH do not establish Cushing syndrome. Renal impairment can reduce urine-test reliability, estrogen can raise cortisol-binding globulin and total serum cortisol, and CYP3A4 modifiers can change dexamethasone exposure. Cyclic disease may require repeated testing during symptomatic periods.

Quick check

0 of 1 answered
01Which is an accepted initial test for suspected endogenous Cushing syndrome?
Answer every question to submit.
67.03

Lesson

Classifying the ACTH Pattern

After endogenous hypercortisolism is established, plasma ACTH divides the causal pathway into ACTH-independent adrenal disease and ACTH-dependent pituitary or ectopic disease.

What to learn
  • Suppressed ACTH
  • Normal or elevated ACTH
  • Adrenal source
  • Pituitary source
  • Ectopic ACTH
Causal branchClassify confirmed hypercortisolism with ACTH
01LowACTH independent

Localize autonomous adrenal cortisol production

02MeasurableACTH dependent

Differentiate pituitary and ectopic secretion

03BorderlineRepeat and contextualize

Protect the branch point from handling and assay error

Follow suppressed ACTH

Persistently low ACTH in confirmed hypercortisolism points toward ACTH-independent cortisol production, usually from an adrenal lesion or bilateral adrenal disorder. Adrenal imaging follows this biochemical branch.

Follow measurable ACTH

Normal or elevated ACTH in confirmed hypercortisolism indicates ACTH-dependent disease. The principal branches are a pituitary corticotroph tumor and ectopic ACTH secretion, with rare CRH-driven states.

Respect assay context

ACTH is unstable and requires careful collection and processing. Mild or cyclic disease can create borderline patterns, so source localization should integrate repeated biochemistry rather than force a single ambiguous value into a definitive category.

Quick check

0 of 1 answered
01Confirmed hypercortisolism with persistently suppressed ACTH most strongly directs evaluation toward what source?
Answer every question to submit.
67.04

Lesson

Localizing the Source

Imaging localizes a biochemically classified disorder. It does not prove hormone secretion merely because a pituitary or adrenal lesion is visible.

What to learn
  • Pituitary MRI
  • Adrenal imaging
  • Ectopic search
  • Inferior petrosal sinus sampling
  • Incidental lesions
Source mapLet biochemistry choose the image
01AdrenalSuppressed ACTH

Use adrenal imaging after ACTH-independent classification

02PituitaryMeasurable ACTH

MRI supports but does not prove a corticotroph source

03ResolvePetrosal sinus sampling

Selected discordant cases require central-to-peripheral ACTH comparison

Image the correct branch

Pituitary MRI follows ACTH-dependent classification, while adrenal CT or MRI follows ACTH-independent classification. Small pituitary lesions and adrenal nodules are common enough that imaging must remain subordinate to endocrine evidence.

Separate pituitary from ectopic ACTH

When pituitary imaging is negative, equivocal, or discordant, bilateral inferior petrosal sinus sampling can compare central and peripheral ACTH after appropriate stimulation. The test distinguishes a pituitary source but does not reliably lateralize every microadenoma.

Search for ectopic disease deliberately

Ectopic ACTH evaluation is guided by biochemical evidence, disease tempo, potassium and androgen patterns, and targeted imaging. Severe rapid hypercortisolism may require cortisol control while localization proceeds.

Quick check

0 of 1 answered
01Why should a small pituitary lesion not automatically be labeled Cushing disease?
Answer every question to submit.
67.05

Lesson

Severity, Comorbidity, and Urgent Control

Cortisol excess increases short-term and long-term risk through infection, thrombosis, hypertension, hypokalemia, hyperglycemia, psychiatric disease, myopathy, fracture, and cardiovascular injury.

What to learn
  • Infection
  • Thrombosis
  • Hypokalemia
  • Hyperglycemia
  • Psychiatric and bone risk
Urgency mapControl multisystem cortisol toxicity
01ThreatInfection and thrombosis

Search actively because ordinary warning signs may be muted

02StabilizePotassium, glucose, and pressure

Treat immediate injury while cortisol control develops

03EscalateRapid cortisol control

Severe disease may need intensive or definitive therapy

Grade the clinical urgency

Severe Cushing syndrome can deteriorate before a definitive operation is available. Infection may present with muted inflammatory signs, thrombosis risk is increased, and profound cortisol excess can activate mineralocorticoid receptors and produce hypertension and hypokalemia.

Treat cortisol-dependent injury

Control blood pressure, potassium, glucose, infection, thrombosis risk, bone loss, and psychiatric symptoms while reducing cortisol exposure. Management is individualized because comorbidities, drug interactions, and procedural timing alter the safest plan.

Use rapid control when necessary

Very severe disease may require rapidly titrated steroidogenesis inhibition, a block-and-replace strategy in expert care, combination therapy, or urgent bilateral adrenalectomy when medical control is inadequate or unavailable.

Quick check

0 of 1 answered
01Which finding most strongly raises urgency in a patient with known Cushing syndrome?
Answer every question to submit.
67.06

Lesson

Cause-Directed Surgery and Remission

Removal of the cortisol- or ACTH-secreting tumor is first-line for most resectable endogenous disease because it treats the cause rather than only blocking cortisol action.

What to learn
  • Transsphenoidal surgery
  • Adrenalectomy
  • Postoperative hypocortisolism
  • HPA recovery
  • Recurrence surveillance
Cause-directed careRemove the source and measure recovery
01ResectPituitary, adrenal, or ectopic tumor

Match the operation to established localization

02ReplacePostoperative hypocortisolism

Support the suppressed normal axis during recovery

03FollowPersistent or recurrent disease

Long-term biochemical surveillance remains necessary

Match the operation to the source

Pituitary Cushing disease is generally treated with transsphenoidal surgery by an experienced pituitary surgeon. Unilateral cortisol-producing adrenal tumors are treated with adrenalectomy, while ectopic ACTH therapy targets the source when feasible.

Interpret the postoperative state

Low cortisol after successful resection often indicates remission and requires glucocorticoid replacement plus adrenal-insufficiency education. Recovery of the remaining HPA axis can take months or longer and is assessed before replacement is stopped.

Expect long-term follow-up

Persistent cortisol excess requires additional treatment. Recurrence can occur years after apparent remission, so symptoms, late-night cortisol physiology, and appropriate biochemical testing remain part of lifelong follow-up.

Quick check

0 of 1 answered
01What is the usual first-line treatment for resectable pituitary Cushing disease?
Answer every question to submit.
67.07

Lesson

Adrenal Steroidogenesis Inhibitors

Steroidogenesis inhibitors lower cortisol by blocking adrenal enzymes, but each target creates a distinct pattern of speed, precursor accumulation, interaction, and organ toxicity.

What to learn
  • Osilodrostat
  • Metyrapone
  • Levoketoconazole
  • Ketoconazole
  • Block and replace
Enzyme controlLower cortisol while tracking pathway diversion
01BlockCYP11B1

Osilodrostat and metyrapone reduce terminal cortisol synthesis

02BroadenSteroidogenic CYP inhibition

Levoketoconazole adds hepatic, QT, and interaction constraints

03BalanceTitrate or block and replace

Choose control strategy from severity and variability

Block CYP11B1

Osilodrostat and metyrapone inhibit 11-beta-hydroxylase, lowering cortisol while increasing upstream precursors. Monitor for hypocortisolism, hypokalemia, hypertension, edema, androgenic effects, and QT-related risk where applicable.

Use azole chemistry carefully

Levoketoconazole inhibits several steroidogenic CYP enzymes and carries important hepatic injury and QT prolongation risks plus substantial interaction potential. Historical oral ketoconazole use requires the same recognition that fungal and adrenal CYP inhibition are not selective.

Choose titration strategy

A titration-to-normal approach adjusts drug to biochemical and clinical response. In severe or highly variable disease, expert teams may fully block cortisol synthesis and add physiologic glucocorticoid replacement. Every approach requires education for hypocortisolism and stress illness.

Quick check

0 of 1 answered
01Which enzyme is a principal target of osilodrostat and metyrapone?
Answer every question to submit.
67.08

Lesson

Pituitary-Directed and Receptor-Blocking Therapy

Medical therapy can reduce pituitary ACTH secretion or block glucocorticoid action, but the measured endpoint differs fundamentally between secretion control and receptor antagonism.

What to learn
  • Pasireotide
  • Cabergoline
  • Mifepristone
  • Hyperglycemia
  • Clinical monitoring
Targeted therapyMatch the endpoint to the mechanism
01PituitaryPasireotide

Reduce ACTH while monitoring severe hyperglycemia risk

02Selected useCabergoline

Off-label pituitary therapy requires response surveillance

03ReceptorMifepristone

Judge clinical response because cortisol does not normalize reliably

Reduce pituitary secretion

Pasireotide is a somatostatin analog approved for adults with Cushing disease when pituitary surgery is not an option or has not been curative. Hyperglycemia is a major toxicity, with additional gallbladder, hepatic, cardiac, and hypocortisolism monitoring. Cabergoline is used off label in selected pituitary disease.

Block the receptor

Mifepristone blocks glucocorticoid and progesterone receptors. Its labeled Cushing indication is control of hyperglycemia in adults with endogenous disease, glucose intolerance or type 2 diabetes, and failed or unsuitable surgery.

Monitor the mechanism

Cortisol can remain high or rise during mifepristone therapy, so dose response and glucocorticoid withdrawal are judged clinically rather than by cortisol normalization. Hypokalemia, hypertension, endometrial effects, pregnancy risk, QT effects, and CYP3A interactions require active management.

Quick check

0 of 1 answered
01Why is serum cortisol not a treatment target during mifepristone therapy?
Answer every question to submit.
67.09

Lesson

Radiation, Bilateral Adrenalectomy, and Long-Term Recovery

Persistent or recurrent disease may require repeat surgery, radiation, combination medical therapy, or bilateral adrenalectomy, each trading rapid cortisol control against delayed effects or permanent endocrine consequences.

What to learn
  • Repeat surgery
  • Radiation
  • Bilateral adrenalectomy
  • Corticotroph tumor progression
  • Recovery and quality of life
Durable sequencePlan beyond the next cortisol result
01BridgePituitary radiation

Medical control may be needed during delayed response

02DefinitiveBilateral adrenalectomy

Rapid control creates permanent replacement dependence

03RecoverLifelong surveillance

Track recurrence, tumor behavior, hormones, and comorbidity repair

Use delayed therapies with a bridge

Pituitary radiation can provide delayed control after persistent or recurrent disease, but medical therapy may be needed while the effect develops. New pituitary deficits can appear over time and require surveillance.

Understand bilateral adrenalectomy

Bilateral adrenalectomy rapidly removes endogenous cortisol production but creates permanent primary adrenal insufficiency requiring lifelong glucocorticoid and mineralocorticoid replacement, emergency education, and stress dosing.

Follow the entire disease

After adrenalectomy for ACTH-dependent disease, ACTH and pituitary imaging monitor corticotroph tumor progression. Across all treatments, cardiovascular, metabolic, bone, psychiatric, cognitive, reproductive, and functional recovery can lag behind biochemical control.

Quick check

0 of 1 answered
01What permanent consequence follows bilateral adrenalectomy?
Answer every question to submit.

Module test

Check the connections.

Each attempt draws 10 questions from the complete 100 question bank.

100 questions in this module bank10 questions per attempt

Each attempt draws a fresh set and rearranges the answer choices.

References

Current clinical foundation.

Lecture material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.

  1. Endocrine Society diagnosis of Cushing syndrome guideline
  2. Endocrine Society treatment of Cushing syndrome guideline
  3. 2021 Pituitary Society Cushing disease consensus
  4. Current Isturisa prescribing information
  5. Current Recorlev prescribing information
  6. Current Signifor prescribing information
  7. Current Korlym prescribing information
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