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.
- Cushing syndrome
- Cushing disease
- Exogenous exposure
- Discriminating features
- Pseudo-Cushing states
Bruising, weakness, striae, fracture, diabetes, and hypertension cluster
Oral, injected, inhaled, topical, ocular, and hidden products count
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.
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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.
- Late-night salivary cortisol
- 24-hour urine free cortisol
- One-milligram dexamethasone suppression
- False positives
- Cyclic disease
Repeated sampling tests loss of the nocturnal low point
Complete collections estimate daily unbound cortisol excretion
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. Night-shift work or variable bedtimes may make this test unsuitable; do not assume that moving collection to daytime restores validity. An endocrinologist should choose an appropriate alternative. Acute stress, tobacco, contamination, and collection technique also affect 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.
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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.
- Suppressed ACTH
- Normal or elevated ACTH
- Adrenal source
- Pituitary source
- Ectopic ACTH
Localize autonomous adrenal cortisol production
Differentiate pituitary and ectopic secretion
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.
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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.
- Pituitary MRI
- Adrenal imaging
- Ectopic search
- Inferior petrosal sinus sampling
- Incidental lesions
Use adrenal imaging after ACTH-independent classification
MRI supports but does not prove a corticotroph source
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. Confirm active hypercortisolism before sampling, especially with cyclic disease. 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.
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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.
- Infection
- Thrombosis
- Hypokalemia
- Hyperglycemia
- Rapid cortisol control
Search actively because ordinary warning signs may be muted
Treat immediate injury while cortisol control develops
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 oral steroidogenesis inhibition, combination therapy, block-and-replace management, or urgent bilateral adrenalectomy. Intravenous etomidate can suppress cortisol synthesis in a closely monitored inpatient setting, usually intensive care, when immediate control is required and oral treatment is not feasible, with continuous specialist monitoring and glucocorticoid replacement readiness.
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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.
- Transsphenoidal surgery
- Adrenalectomy
- Postoperative hypocortisolism
- HPA recovery
- Recurrence surveillance
Match the operation to established localization
Support the suppressed normal axis during recovery
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.
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Lesson
Medicinal Chemistry of Cortisol Control
Cushing medicines exploit two different molecular strategies: coordinate the heme environment of steroidogenic CYP enzymes to slow cortisol synthesis, or occupy the glucocorticoid receptor without activating it.
- Steroidogenic CYP heme
- Nitrogen heterocycles
- CYP11B1 selectivity
- Steroid receptor antagonism
- Structure-linked off-target effects
Broad enzyme binding links cortisol suppression with hepatic and interaction constraints
Terminal blockade lowers cortisol while upstream precursors accumulate
Clinical response matters when the receptor is blocked but cortisol remains measurable
Coordinate steroidogenic CYP enzymes
Ketoconazole and levoketoconazole contain an imidazole nitrogen that can coordinate CYP heme iron. That interaction explains broad steroidogenic CYP inhibition, extensive interaction potential, and the need to separate enzyme blockade from organ toxicity.
Aim nearer the terminal cortisol step
Metyrapone uses a pyridine-containing scaffold to inhibit CYP11B1, while osilodrostat is a nonsteroidal inhibitor with greater CYP11B1 potency in vitro. Enzyme potency alone does not establish superior clinical safety or outcomes. Blocking 11-beta-hydroxylase lowers cortisol but raises 11-deoxycortisol and can divert precursors toward mineralocorticoid or androgen activity.
Antagonize the receptor
Mifepristone preserves a steroid-like framework but carries substituents that favor glucocorticoid and progesterone receptor antagonism. Receptor blockade explains why clinical response replaces cortisol concentration as the treatment endpoint and why pregnancy and endometrial safety cannot be separated from its pharmacology.
Keep chemistry clinically bounded
Aminoglutethimide and trilostane illustrate older approaches to upstream steroid synthesis, but they are not presented as routine contemporary Cushing therapy. Relacorilant is a selective glucocorticoid receptor antagonist, but its current US approval is for an oncology indication, not endogenous Cushing syndrome.
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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.
- Osilodrostat
- Metyrapone
- Levoketoconazole
- Ketoconazole
- Block and replace
Osilodrostat and metyrapone reduce terminal cortisol synthesis
Levoketoconazole adds hepatic, QT, and interaction constraints
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.
Apply the osilodrostat label
Isturisa now covers adult endogenous Cushing syndrome when surgery is unavailable or unsuccessful. Usual initiation is 2 mg twice daily; increases are spaced at least two weeks apart, with a 30 mg twice-daily ceiling. Hepatic impairment requires lower starting doses. Correct potassium and magnesium, obtain an ECG before treatment and within one week, and follow cortisol and symptoms during titration. Strong CYP3A4 inhibitors require halving the dose. Cortisol suppression can persist after stopping treatment; symptomatic adrenal insufficiency requires drug interruption and glucocorticoid treatment.
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.
Make levoketoconazole monitoring explicit
Recorlev starts at 150 mg twice daily; increase the total daily dose by 150 mg no sooner than every two to three weeks, up to 600 mg twice daily. Check liver enzymes and bilirubin weekly for six weeks, every two weeks for six more weeks, then monthly for three months. Obtain an ECG before each increase. Baseline QTcF above 470 ms, specified liver disorders, and certain interacting drugs are contraindications, not merely reasons for closer observation. Consult the label for interruption and permanent-discontinuation thresholds. Recorlev is not approved as an antifungal.
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.
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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.
- Pasireotide
- Cabergoline
- Mifepristone
- Hyperglycemia
- Clinical monitoring
Reduce ACTH while monitoring severe hyperglycemia risk
Off-label pituitary therapy requires response surveillance
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; monitor for loss of cortisol control and new compulsive behaviors, including gambling or uncontrolled shopping.
Distinguish pasireotide formulations
The referenced Signifor is subcutaneous: usual initiation is 0.6 or 0.9 mg twice daily. Do not apply that schedule to a depot product. Obtain baseline glucose, HbA1c, liver tests, electrolytes, ECG and gallbladder ultrasound. Check glycemia weekly for the first two to three months and after dose escalation; monitor liver tests and gallbladder health. New greasy stools, bloating or weight loss warrants evaluation for pancreatic exocrine insufficiency. Moderate hepatic impairment requires lower dosing; avoid use in severe hepatic impairment.
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.
Use mifepristone with a rescue plan
Korlym begins at 300 mg daily with food; titration is clinical, with a ceiling of 1200 mg/day and 20 mg/kg/day, subject to lower organ-function and interaction limits. Exclude pregnancy before treatment and after interruptions longer than 14 days; use nonhormonal contraception through one month after stopping. Life-saving systemic corticosteroid therapy is a contraindication. Suspected adrenal insufficiency requires immediate interruption and glucocorticoid rescue; high cortisol does not exclude dangerous receptor blockade. Check potassium after initiation or escalation and review the full interaction list.
Monitor the mechanism
Cortisol can remain high or rise during mifepristone therapy, so dose response and suspected adrenal insufficiency are judged clinically rather than by cortisol normalization. Hypokalemia, hypertension, endometrial effects, pregnancy risk, QT effects, and CYP3A interactions require active management.
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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.
- Repeat surgery
- Radiation
- Bilateral adrenalectomy
- Corticotroph tumor progression
- Recovery and quality of life
Medical control may be needed during delayed response
Rapid control creates permanent replacement dependence
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 bilateral adrenalectomy for known pituitary Cushing disease or presumed occult ectopic ACTH secretion, monitor ACTH and pituitary imaging for corticotroph tumor progression. In occult cases, the original source can later prove pituitary; a confirmed ectopic tumor needs its own source-directed surveillance. Across all treatments, cardiovascular, metabolic, bone, psychiatric, cognitive, reproductive, and functional recovery can lag behind biochemical control.
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Module practice
Check the connections.
Each attempt draws 10 questions from the complete 40 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Core source material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.
- Osilodrostat steroidogenic CYP selectivity study
- Historical human trilostane study (1983)
- Historical aminoglutethimide report (1966)
- Human CYP17A1 inhibitor binding study (Garrido et al., 2014)
- CYP11B1 metyrapone complex study (2021)
- 2021 Pituitary Society consensus: accessible author manuscript
- FDA relacorilant Cushing orphan-indication status
- FDA 2026 novel approvals: relacorilant oncology indication
- Endocrine Society diagnosis of Cushing syndrome guideline
- Endocrine Society treatment of Cushing syndrome guideline
- 2021 Pituitary Society Cushing disease consensus
- Current Isturisa prescribing information
- Current Recorlev prescribing information
- Current Signifor prescribing information
- Current Korlym prescribing information