Executive summary of the consensus document for the management of severe Cushing's syndrome: Consensus document of the Neuroendocrinology Focus Group of the Spanish Society of Endocrinology and Nutrition (SEEN).

Osilodrostat dosage is adjusted based on 24-h urinary free cortisol (UFC) levels. However, approximately 1 week is required to obtain the results. In contrast, serum cortisol levels are available soon after sampling, allowing the determination of osilodrostat doses promptly. However, this issue remains poorly understood. Therefore, this study aimed to determine whether a simultaneous assay of serum cortisol and UFC concentrations is useful in patients with Cushing syndrome (CS) receiving osilodrostat. This was a retrospective cross-sectional study. A total of 71 paired samples in six patients with CS during osilodrostat treatment were analyzed in this study. The 24-h urine sample collection was started from the day before blood sampling, and UFC and morning serum cortisol levels were measured on the same day. Commercially available immunoassay kits were used for the hormone measurements. A significant positive correlation between morning cortisol levels and UFC levels was observed. Receiver operating characteristic analysis showed a cut-off of 21.5 μg/dL for serum cortisol as the best indicator to predict high UFC levels. The cut-off secured UFC samples >3× the upper limit of normal. However, the positive predictive value of serum cortisol levels in predicting low UFC was considerably low. A serum cortisol level <5.0 μg/dL, which is often used to suggest adrenal insufficiency, captured patients with hypocortisolism even when the serum cortisol and UFC results were discordant. Simultaneous measurements of single morning serum cortisol and UFC levels on the same day will promote safety in patients with CS who are being treated with osilodrostat.

It can be difficult to establish the diagnosis of Cushing's Syndrome (CS) in patients with mild or nonspecific clinical and biochemical findings, because available diagnostic tests have limited predictive values. We hypothesized that measurement of 24-h cortisol production rates (CPRs) might be a more sensitive indicator of CS in such patients. We measured CPRs in 28 patients with suspected CS (but equivocal biochemical findings) and in 22 healthy control subjects, by infusing tracer amounts of deuterated cortisol, with simultaneous measurements of 24-h urine free cortisol (UFC) levels; and we frequently sampled serum cortisol levels. CPRs were calculated from the ratio of isotopic enrichment to isotopic dilution of cortisol measured by gas chromatography-negative ion chemical ionization mass spectrometry. Nine of the patients proved to have CS by surgery (CS-Yes), whereas 19 patients were determined not to have CS by biochemical testing (CS-No). Mean 24-h UFCs, nocturnal serum cortisol levels, and CPRs were higher in CS-Yes, compared with CS-No and normal subjects. However, one CS-Yes patient had a normal 24-h UFC, two had normal nocturnal serum cortisol levels, and two had normal 24-h CPRs. There was extensive overlap in all of the biochemical parameters between the CS-Yes and the CS-No groups. Thus, measurement of CPR does not seem to offer any diagnostic advantage over available tests for the diagnosis of CS. Patients with proven CS can have normal UFC levels, normal CPRs, or normal nocturnal cortisol levels, whereas patients not thought to have CS may have elevated levels of any one or more these parameters.

Introduction Glucose-dependent insulinotropic peptide (GIP)-dependent primary bilateral macronodular adrenal hyperplasia (PBMAH) is a rare cause of Cushing's syndrome. It has germline genetic predisposition and requires for personalized approaches to investigation and therapy. We aimed to present the rare case of a GIP-dependent PBMAH patient with unusually severe cortisol secretion and a KDM1A inactivation with an accompanying haematological co-morbidity related to that mutation. Clinical Case A 41-year-old woman presented with a 5-kg weight gain in last 6 months, irritability and fatique. Physical examination revealed elevated blood pressure, increased supraclavicular fat pads, and abdominal obesity. The cortisol level was 25.9 (6.7-22.6) µg/dL in the morning, 16.9 µg/dL in the late night, and 6.5 µg/dL in the morning after an overnight 1 mg of dexamethasone. Urinary free cortisol (UFC) level was also elevated to 2150 (58-403) µg/24-h. The early morning plasma ACTH level was 1.5 (7-63) pg/mL. Abdominal imaging revealed 29×23 mm adenomas on the right and 46×35 mm on the left with high fat content. Cortisol was stimulated by the administration of mixed meals (+537%) but not by TRH, GnRH, metoclopramide or upright posture. The response to mixed meals was blunted by pretreatment with subcutaneous 100 mg octreotide. Following the patient's diagnosis of GIP-dependent PBMAH, octreotide LAR therapy was initiated. Although inducing a significant acute suppression of UFC and improvement in symptoms during the first 3 months, the UFC began to rise due to the resistance in the following period (Figure 1). After 9 months of octreotide LAR treatment, left adrenalectomy was performed according to the adrenal volumetric assessment. Histopathology was reported as diffuse macronodular adrenal hyperplasia without internodular atrophy. Even though the patient had a unilateral adrenalectomy, adrenal insufficiency occurred in the postoperative period. Subsequently, the patient has been closely monitored and followed up with a physiological, divided-dose hydrocortisone replacement regimen for 7 months. A germline heterozygous variant in the KDM1A gene in the patient's blood sample and a recurrent deletion in the short p arm of chromosome 1 harboring the KDM1A locus in the adrenal sample were identified. When screened for diseases associated with the KDM1A mutation, monoclonal gammopathy of undetermined significance (MGUS) was detected in the patient with mild anemia, and genetic counseling was also provided. Conclusion The management of GIP-dependent PBMAH remains controversial, and further therapeutic options are under investigation. Due to the very limited number of case reports and the heterogeneous nature of the disease, special features of our case, which are severe cortisol excess, accompanying MGUS, the vanishing effect of octreotide, and adrenal insufficiency after unilateral adrenalectomy, might contribute to the existing literature.Figure 1.Urinary free cortisol levels following octreotide therapyUFC: Urinary free cortisol, ULN: Upper limit normal, LAR: Long acting release

Cushing syndrome (CS) is characterized by increased morbidity and mortality compared to the general population. However, there are patients who have more clinical aggressive forms than others. Aim of the study is to evaluate whether the degree of hypercortisolism, defined by the number of times urinary free cortisol (UFC) levels exceed the upper limit of the normal range (ULN), is related to the worsening of phenotypic features, as well as metabolic and cardiovascular parameters, in a cohort of CS patients. A cross-sectional study was conducted on 192 patients with active CS, consecutively presenting at the outpatients' clinic of the University Hospitals of Ancona, Naples, and Palermo. Patients were grouped into mild (UFC not exceeding twice the ULN), moderate (2-5 times the ULN), and severe (more than 5 times the ULN) hypercortisolism. Thirty-seven patients (19.3%) had mild, 115 (59.8%) moderate, and 40 (20.9%) severe hypercortisolism. A significant trend of increase among the three groups was demonstrated for 8-, 16-, and 24-h serum cortisol levels (p<0.001) and serum cortisol after low dose of dexamethasone suppression test (p=0.001). No significant trend of increase was found regarding phenotype and comorbidities. The degree of hypercortisolism by itself does not appear to be a sufficient parameter to express the severity of CS. Therefore, estimating the severity of CS according to biochemical parameters remains a challenge, while the clinical phenotype and the associated comorbidities might be more useful to assessing the severity of the CS.

Severe Cushing's syndrome elicited by ectopic ACTH syndrome (EAS) or adrenal carcinoma (ACC) can threaten life in the short term. The effectiveness of oral administration of the inhibitors of steroidogenesis ketoconazole and metyrapone in this situation is poorly described. To report the short-term effectiveness and tolerability of metyrapone and ketoconazole elicited either by EAS or by ACC in patients exhibiting severe hypercortisolism. Retrospective analysis of data obtained for patients with urinary free cortisol (UFC) level estimated to be fivefold the upper limit of the normal range (ULN). A total of 14 patients with EAS and eight with ACC treated in two tertiary-care university hospitals. Metyrapone and ketoconazole treatment in combination (along with symptomatic treatments for co-morbidities). Evolution of clinically relevant endpoints (blood pressure, kalaemia and glycaemia) and biological intensity of hypercortisolism 1 week and 1 month after starting steroidogenesis inhibition. After 1 week of treatment, median UFC fell from 40.0 to 3.2 ULN and from 16.0 to 1.0 ULN in patients with EAS and ACC respectively. Median UFC after 1 month of treatment was 0.5 and 1.0 ULN in patients with EAS and ACC respectively and UFC values were normal in 73 and 86% of patients respectively. Clinical status improved dramatically along with kalaemia, glycaemia and blood pressure, allowing a decrease in the relevant treatments.Side effects were minimal and only two patients (one EAS and one ACC) experienced plasma transaminase elevations necessitating ketoconazole withdrawal. Metyrapone-ketoconazole combination therapy is well tolerated and provides rapid control of endocrine cancer-related life-threatening hypercortisolism.

Medical treatment is increasingly used in patients with Cushing's syndrome (CS). Metyrapone (MET) is an inhibitor of 11β-hydroxylase: retrospective studies reported a decrease of cortisol secretion in 50% of cases. We evaluated the effectiveness of MET in an observational study, considering the normalization of urinary-free cortisol (UFC) and late-night salivary cortisol (LNSC) levels. We enrolled 31 patients with CS, treated with MET for at least 1 month (16 for primary treatment and 15 after surgical failure). A planned dose-titration regimen considering baseline UFC levels was adopted; MET dose was uptitrated until UFC normalization, surgery, or side effect occurrence. UFC and LNSC levels were routinely measured by liquid chromatography-tandem mass spectrometry. Patients were treated with a median dose of 1000 mg for 9 months. UFC and LNSC decreased quickly after the first month of treatment (-67 and -57% from baseline), with sustained UFC normalization up to 12 and 24 months (in 13 and 6 patients, respectively). UFC and LNSC normalized later (after 3-6 months) in patients with severe hypercortisolism (>5-fold baseline UFC). Regarding the last visit, 70 and 37% of patients normalized UFC and LNSC, respectively. Body weight reduction (-4 kg) was observed after UFC normalization. Severe side effects were not reported, half of the female patients complained of hirsutism, and blood pressure was not increased. MET therapy is a rapid-onset, long-term effective, and safe medical treatment in CS patients, achieving UFC normalization (in 70% of patients) more than cortisol rhythm recovery (in 37% of subjects).

Pasireotide: Somatostatin analog for Cushing disease

Obesity and insulin resistance, menstrual abnormalities and clinical and biochemical signs of hyperandrogenism are common features in women with polycystic ovary syndrome (PCOS) and Cushing's syndrome (CS). Further, an overdrive of the pituitary-adrenal axis has been documented in PCOS and this condition is often present in women with CS. For this reason, screening for hypercortisolism is often needed in obese women with polycystic ovaries. The aim of this study was to compare the diagnostic value of different screening tests for CS in a population of obese premenopausal women with PCOS and without PCOS (OB) and in a group of patients with CS. We reviewed retrospectively the case records of 117 obese women of reproductive age (60 PCOS and 57 OB, BMI 25.1-70.1, 13-45 yr) who were screened for CS at our Institution in the years 1995-2001 and turned out to be free of the disease. Data were compared with those of 58 premenopausal obese women with active CS (BMI 25.1-50.2 kg/m2, 18-45 yr). Screening for CS was performed by urinary free cortisol (UFC) (three consecutive 24-h urine collections), cortisol circadian rhythm (blood samples taken at 08:00-17:00-24:00 h), and 1 mg overnight dexamethasone suppression test (DST). A 24:00 h plasma cortisol (MNC) of 207 nmol/l, a UFC of 221 nmol/day and plasma cortisol after DST of 50 nmol/l and 138 nmol/l were taken as cut-off values for the diagnosis of CS. As expected, patients with CS showed elevated basal and post-dexamethasone plasma cortisol and UFC levels (p < 0.001 vs OB and PCOS). PCOS had higher UFC (p < 0.005) but not MNC and post-DST plasma cortisol levels compared to OB. DST showed the greatest specificity and diagnostic accuracy in differentiating CS from PCOS and OB (both p < 0.05 vs MNC and UFC, according to the 138 nmol/l criterion) while MNC and UFC displayed a similar discriminatory value. However, by using a lower threshold (50 nmol/l) as response criterion, there were no diagnostic differences between DST and the other tests. Specificity and diagnostic accuracy of UFC measurement was lower in PCOS than in OB (both p < 0.05) whilst there were no differences between groups for DST and MNC. Similarly, the area under the ROC curve relative to DST, giving an estimate of the inherent diagnostic accuracy of the test, was slightly greater than those of MNC and UFC (z = 0.694 and z = 0.833 for DST vs MNC and UFC, respectively, both p = NS). These results indicate that the 1-mg DST and MNC are unaffected by the presence of PCOS and can be safely used to screen for CS premenopausal obese women with PCOS, while caution should be exercised in interpreting mildly elevated UFC levels in these patients.

Tumors producing adrenocorticotropic hormone (ACTH) or corticotropin releasing hormone (CRH) often remain undiagnosed until severe Cushing's syndrome appears, and it may be difficult to distinguish from Cushing's syndrome due to pituitary tumors. Many patients suffer from disease spread, with metastases in the liver or other locations, and the main symptoms may be mineral disturbances, diabetes mellitus, or psychological symptoms from the severe hypercortisolism. Bilateral adrenalectomy may alleviate this situation, but is sometimes a troublesome procedure in these severely ill patients. We have retrospectively investigated 8 patients with ectopic Cushing's syndrome who have undergone bilateral adrenalectomy at the University Hospital in Uppsala. In addition, another 5 patients who underwent bilateral adrenalectomy for other reasons (recurrent pituitary Mb Cushing or bilateral hyperplasia) were scrutinized for technical considerations. Indications, timing of surgery, and operative procedures were studied to identify signs that may support our approach to management in the future. Curative surgery was not possible in any of the cases with ectopic Cushing's syndrome. Of the 13 operated patients, handport-assisted laparoscopic adrenalectomy was successfully performed bilaterally in 5 patients and unilaterally in combination with contralateral open surgery in 1 patient; conventional open surgery was performed on 7 patients, 3 of which were conversions from intitial handport-assisted procedures. Non-fatal complications occurred in 4 out of 10 patients. We conclude that bilateral handport-assisted laparoscopic adrenalectomy is safe, and that all surgical techniques in these severely ill patients may be troublesome and technically demanding. Early surgical intervention may reduce the technical disadvantages. Moreover, bilateral adrenalectomy can substantially reduce the symptoms of Cushing's syndrome, although effects on mortality are not obvious.

Metyrapone is commonly used in the initial management of Cushing's syndrome to reduce hypercortisolemia, but its optimal dosage and timing can vary significantly between patients. Currently, there are limited guidelines on adjustment methods for its administration to individual needs. This study aimed to evaluate responsiveness of each patient to metyrapone and identify the patient characteristics associated with the indices of cortisol responsiveness following a low-dose metyrapone. This single-center retrospective observational study included 15 treatment-naïve patients, 7 of whom had Cushing's disease and 8 had adrenal Cushing's syndrome. Serum cortisol levels were measured hourly from the time of administration of 250 mg of metyrapone up to four hours afterward. Parameters analyzed included the nadir of serum cortisol levels (Fnadir), the difference between basal and nadir serum cortisol levels (ΔF), the time to nadir, and the characteristics of the patients. As a result, cortisol suppression curves showed significant variability among patients, particularly in the time to nadir. While the median time to nadir was 2 hours, 20% of patients required 4 hours or more, and these responses were not associated with patient characteristics. Fnadir was positively correlated with early-morning serum cortisol levels, serum cortisol levels after low-dose dexamethasone suppression test (LDDST), and urinary free cortisol (UFC) levels, whereas ΔF was positively correlated with late-night serum cortisol levels, serum cortisol levels after LDDST, and UFC levels. In conclusion, the duration of response to metyrapone appeared unpredictable in patients with Cushing's syndrome and did not correlate with patient characteristics at baseline. Tracking the effect of metyrapone following a single low-dose administration may explain this variability and provide insights for optimizing individual dosing regimens. Further studies are required to validate these findings and guide more personalized treatment adjustments.

Endogenous Cushing's syndrome (CS) is a rare disease, and usually characterized by hypertension, diabetes, obesity, osteoporosis, facial rounding, dorsocervical fat pad, thin skin, purple striae, hirsutism, and mood disorders. Efficient diagnostic and screening strategies lead to the diagnosis of a significantly higher number of cases of CS. As a screening test for CS, the Endocrine Society's Clinical Practice Guidelines recommend a single test with a high diagnostic accuracy, among the 1-mg dexamethasone suppression test (1-mg DST), late night salivary cortisol (LNSC), and 24h urinary free cortisol (UFC). In normal subjects, administering a higher than physiological dose of glucocorticoids prompts the suppression of cortisol secretion. The 1-mg DST explores this normal feedback reaction from the hypothalamic-pituitary-adrenal axis (HPA). It is a simple dynamic test, usually performed in outpatients. A morning serum cortisol level <50nmol/L suffices to exclude CS, unless there is a strong clinical suspicion to suggest otherwise. The HPA axis reaches a nadir just after a person has fallen asleep, but its circadian rhythm is impaired in CS patients, who feature higher cortisol values at night, which are easy to measure in saliva (the LNSC assay). Saliva collection is also suitable for outpatients since cortisol is stable at room temperature and the collection device can be mailed to the laboratory for analysis. UFC levels reflect the integrated tissue exposure to free cortisol over 24h, and thus provide a particular picture of endogenous hypercortisolism. In most cases, high UFC levels coincide with severe hypercortisolism. UFC is used not only to diagnose CS, but also to monitor its response to medical treatment. All screening tests have procedural snares: some drugs can interfere with the DST; false-positive or false-negative LNSC results may be due to an inadequate soaking of the device or to cyclic CS; and in the case of UFC it is important to ensure that patients provide complete urine collections with appropriate total volumes. Measuring cortisol with antibody-based immunoassays can also generate false-positive results due to cross-reactivity between cortisol, cortisone and other metabolites. Structurally-based assays, such as liquid chromatography with tandem mass spectrometry, only measure cortisol and have only recently become available for use in routine clinical practice. This review summarizes the recent literature on the clinical and biochemical aspects of CS diagnostics with a view to helping physicians choose the best screening test for diagnosing endogenous hypercortisolism.

Hypokalemia is a common feature in patients with Cushing's syndrome (CS). Whether the occurrence of hypokalemia is associated with cortisol and adrenocorticotropic hormone (ACTH) levels is still unclear. Approximately 80% of cases of endogenous CS are due to Cushing's disease (CD). The purpose of this study was to determine the association of hypokalemia with cortisol and ACTH levels in patients with CD. The retrospective study included 195 patients with CD referred to our medical center from January 2011 to December 2017. The results show that 25.64% (50/195) of the patients had hypokalemia. The 24-h urinary free cortisol (UFC) and plasma cortisol levels were significantly higher in patients with hypokalemia than those with normokalemia (P < 0.05). Plasma ACTH levels were similar between the patients with hypokalemia and normokalemia (P > 0.05). Cortisol levels were negatively correlated with plasma potassium levels (08:00: r=-0.344 (P < 0.01), 00:00: r=-0.435 (P < 0.01); 24-h UFC: r=-0.281 (P < 0.05)). There was no significant correlation between the plasma ACTH and potassium (08:00: r=-0.093 (P > 0.05), 00:00: r=-0.184 (P > 0.050)). Our current data suggest that cortisol level, instead of ACTH level, is correlated with plasma potassium level. A high cortisol level may be the principal cause of hypokalemia.

Disclosure: A. DeMarsilis: None. C. Jiang: None. O. Lavrynenko: None. D. Motavalli: None. C. Musurakis: None. Z.H. Taxin: None. E.D. Rosen: Advisory Board Member; Self; Source Bio, Inc.. Consulting Fee; Self; Novartis Pharmaceuticals, Gensaic. M.S. Irwig: None. Background: Ectopic Cushing’s Syndrome (CS) makes up 9-18% of ACTH-dependent CS cases, of which fewer than 15% are attributed to pancreatic neuroendocrine tumors (1). Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) are rare, aggressive carcinomas, often driven by high-grade neuroendocrine components, with a poor prognosis (2). Amphicrine neoplasms contain neuroendocrine and exocrine components in the same cell. Clinical Case: A 34 year-old woman with asthma, hypertension, and depression presented with new onset lower extremity edema, facial hirsutism, mood changes, polyuria and polydipsia. She had an elevated morning serum cortisol of 52 ug/dL (normal &amp;lt; 20) with plasma ACTH 42 pg/mL (normal &amp;lt; 50), 24-hour urine free cortisol of 1003 mcg (normal &amp;lt; 50), K+ of 2.6 mEq/L, and fasting glucose 164 mg/dL. CT showed multiple hepatic lesions, pulmonary nodules, a pancreatic tail lesion, and lymphadenopathy concerning for metastatic disease. Her adrenal glands were thickened bilaterally without nodules. A pituitary MRI was normal. These findings were concerning for ectopic CS. She was admitted due to rapidly developing symptoms. Potassium, insulin, sitagliptin, and prophylactic anticoagulation were started. Spironolactone and ketoconazole were initiated while awaiting biopsy results of liver and pancreas lesions. Osilodrostat was not available and a trial of metyrapone was poorly tolerated. The liver and pancreatic tail lesion biopsy revealed metastatic MiNEN with amphicrine features, of pancreatic origin, with Ki67 proliferation index of 70%. Section staining of pancreas and liver biopsies were negative for ACTH. A Ga-68 Dotatate scan showed minimal uptake, so octreotide was not prescribed. Palliative chemotherapy was planned. Although ketoconazole was titrated to 1600 mg/day, urine free cortisol levels and serum free cortisol levels did not reach target. Cushing disease was considered but not suspected, as ACTH levels remained modest despite a relative decrease in cortisol level. Given significant morbidity from uncontrolled hypercortisolism, and plans for urgent initiation of systemic chemotherapy, after multidisciplinary discussion the patient was treated with a surgical bilateral adrenalectomy. Post-operative morning serum cortisol measured 8.3 ug/dL. After one week, palliative chemotherapy with FOLFIRINOX (oxaliplatin, leucovorin, fluorouracil, and irinotecan) was initiated. She was discharged home on stress dose steroids with plan for taper. Conclusion: Ectopic ACTH secretion is a rare phenomenon, particularly when presenting with a rare case of metastatic pancreatic MiNEN with amphicrine features, associated with significant morbidity. To improve tolerance and survival of further treatment, early surgical bilateral adrenalectomy should be considered.

The aim of the current study was to evaluate the effectiveness of a long-term treatment with sodium valproate in 19 patients with Cushing's disease. Before therapy beginning, the patients were subjected to acute test with 600 mg sodium valproate. Then, they were subjected to a 3-month therapy with sodium valproate at the dose of 600 mg/day before surgery (presurgical study). The 7 patients not surgically cured were subjected again to a 3-month therapy with sodium valproate at the dose of 600 mg/day after surgery (postsurgical study). Circulating ACTH and cortisol and urinary free cortisol levels were evaluated before and monthly after the beginning of the therapy. A decrease of plasma ACTH and serum cortisol levels greater than 50% of baseline was considered as positive response to acute test whereas the normalization of plasma ACTH, serum cortisol and urinary free cortisol levels and the clinical remission were considered as positive response to the long-term treatment. At acute test, 8 patients were considered responders and 11 patients non-responders. In no patient plasma ACTH, serum cortisol and urinary free cortisol were normalized during the long-term treatment. Urinary free cortisol levels significantly decreased (483.2 +/- 33.8 vs 699.4 +/- 67.0 micrograms/24 h), whereas plasma ACTH (302.8 +/- 17.7 vs 183.3 +/- 25.0 ng/l) and serum cortisol (466.5 +/- 23.2 vs 356.7 +/- 19.6 micrograms/l) significantly increased during sodium valproate administration in the 19 patients enrolled in the presurgical study. Plasma ACTH (247.7 +/- 22.3 vs 168.6 +/- 15.0 ng/l), serum cortisol (387.4 +/- 35.8 vs 282.0 +/- 16.0 micrograms/l) and urinary free cortisol (370.9 +/- 70.6 vs 261.3 +/- 37.8 micrograms/24 h) levels significantly increased in the 7 patients enrolled in the postsurgical study. No patient had clinical remission of Cushing's disease. In conclusion, the current study showed that long-term therapy with sodium valproate is not useful in the therapeutic management of Cushing's disease neither as alternative nor as adjunctive therapy to surgery.

Mitotane is highly effective in the long-term management of Cushing's syndrome but has a slow onset of action. Mitotane combined with fast-acting steroidogenesis inhibitors might avoid the need for emergency bilateral adrenalectomy in patients with severe hypercortisolism. Our objective was to assess the efficacy and safety of combination therapy with mitotane, metyrapone, and ketoconazole in severe ACTH-dependent Cushing's syndrome. Eleven patients with severe Cushing's syndrome participated in this follow-up study in a tertiary referral hospital. High-dose therapy combining mitotane (3.0-5.0 g/24 h), metyrapone (3.0-4.5 g/24 h), and ketoconazole (400-1200 mg/24 h) was initiated concomitantly. Twenty-four-hour urinary free cortisol (UFC) excretion (normal values 10-65 μg/24 h) was monitored. Data are reported as medians (range). All 11 patients experienced a marked clinical improvement. UFC excretion fell rapidly from 2737 μg/24 h (range 853-22,605) at baseline to 50 μg/24 h (range 18-298) (P = 0.001) within 24-48 h of treatment initiation and remained low to normal on the combination therapy. In seven patients, metyrapone and ketoconazole were discontinued after 3.5 months (range 3.0-6.0) of combination therapy, and UFC excretion remained controlled by mitotane monotherapy (UFC 17 μg/24 h, range 5-85; P = 0.016). Five patients became able to undergo etiological surgery and are presently in remission. Four of them recovered normal adrenal function after mitotane discontinuation. Adverse effects were tolerable, consisting mainly of gastrointestinal discomfort and a significant rise in total cholesterol and γ-glutamyl transferase levels (P = 0.012 and P = 0.002, respectively). When surgical treatment for severe ACTH-dependent Cushing's syndrome is not feasible, combination therapy with mitotane, metyrapone, and ketoconazole is an effective alternative to bilateral adrenalectomy, a procedure associated with significant morbidity and permanent hypoadrenalism.