Prolactin measurement during inferior petrosal sinus sampling improves the localization of pituitary adenomas in Cushing's disease

Bilateral inferior petrosal sinus sampling in the differential diagnosis of ACTH-dependent Cushing's syndrome: A reappraisal

Cushing's syndrome (CS) is a rare disorder, once exogenous causes have been excluded. However, when diagnosed, the majority of cases are adrenocorticotropic hormone (ACTH)-dependent, of which a substantial minority are due to a source outside of the pituitary, ectopic ACTH syndrome (EAS). Differentiating among pituitary-dependent CS, Cushing's disease (CD) and an ectopic source can be problematic. Because non-invasive tests in the evaluation of CS patients often lack adequate sensitivity and specificity, bilateral inferior petrosal sinus sampling (BIPSS), a minimally invasive procedure performed during the investigation of ACTH-dependent CS, can be extremely helpful. BIPSS is considered to be the gold standard for differentiating CD from the EAS. Furthermore, although such differentiation may indeed be challenging, BIPSS is itself a complex investigation, especially in recent times due to the widespread withdrawal of corticotrophin-releasing hormone and its replacement by desmopressin. We review current published data on this investigation and, in the light of this and our own experience, discuss its appropriate use in diagnostic algorithms.

Does concomitant prolactin measurement ıncrease the accuracy of ınferior petrosal sinus sampling?

INTRODUCTION

Prolactin (PRL) measurement during inferior petrosal sinus sampling (IPSS) can be helpful to improve the accuracy. We aimed to evaluate the effect of measuring PRL levels as a predictor for the accuracy of IPSS and evaluate its impact on the lateralization of adenomas.

METHODS

In this retrospective cohort study, we reviewed 51 patients who had undergone IPSS for the investigation of ACTH-dependent hypercortisolism.

RESULTS

Forty-nine patients had proven Cushing's disease (CD), one had EAS, and the remaining one patient had adrenal adenoma. Forty-seven patients had an above 2 ACTH IPS/P ratio at baseline, and all the post-corticotropin-releasing hormone (CRH) ACTH IPS/P ratios of patients with proven CD were above 3. In these two patients whose ACTH IPS/P ratio at baseline was below 2, PRL IPS/P ratios were above 1.8 in only the dominant side, which was considered secondary to a prolactin intersinus gradient due to the biological effects of the tumor. PRL-adjusted ACTH IPS/P ratios were > 1.3 in all patients with proven CD; it was 0.7 in the patient with EAS. Surgically confirmed positive lateralization was observed in 55.1% of patients with the ACTH gradient, but when PRL-adjusted ACTH IPS/IPS ratios were used in addition to the ACTH gradient, the ratio increased to 67.3%.

CONCLUSION

Although PRL-adjusted ACTH IPS/P ratios can be helpful to improve the accuracy of results during IPSS procedures, a prolactin intersinus gradient towards the ACTH-dominant side in patients with CD may invalidate PRL as an indicator of pituitary venous outflow.

Lateral one-third gland resection in Cushing patients with failed adenoma identification leads to low remission rates: long-term observations from a small, single-center cohort

BACKGROUND

Currently, there are no guidelines for neurosurgeons treating patients with Cushing's disease (CD) when intraoperative adenoma identification is negative. Under these circumstances, a total hypophysectomy or hemi-hypophysectomy on the side indicated by inferior petrosal sinus sampling (IPSS) is the approach being used, although there is a subsequent risk of hypopituitarism. Data on whether one-third lateral pituitary gland resection results in cure of hypercortisolism and low rates of hypopituitarism remain inconclusive.

METHODS

Retrospective single-center study of CD patients with failed intraoperative adenoma identification and subsequent resection of the lateral one-third of the pituitary gland as predicted by IPSS. We assessed (i) histopathological findings, (ii) early and long-term remission rates, and (iii) rates of additional pituitary hormone insufficiency.

RESULTS

Ten women and three men met the inclusion criteria. At 3 months, remission was noted in six (46%) patients: three (23%) had histologically confirmed adenomas, two (15%) had ACTH hyperplasia, and one patient (8%) was positive for Crooke's hyaline degeneration. New pituitary hormone deficits were noted in two patients (15%). After a median (±SD) follow-up of 14±4 years, recurrence was noted in two (15%) patients. Long-term control of hypercortisolism was attained by 10 patients (77%), with additional therapies required in nine (69%) of them.

CONCLUSIONS

In CD patients with failed intraoperative adenoma visualization, lateral one-third gland resection resulted in low morbidity and long-term remission in 31% of patients without the need for additional therapies. Bearing in mind the sample size of this audit, the indication for lateral one-third-gland resection has to be critically appraised and discussed with the patients before surgery.

Revalidation of inferior petrosal sinus sampling: the latest results from a single-center experience

Cushing's disease (CD), which manifests as excess cortisol secretion, is caused by adrenocorticotrophic hormone (ACTH)-secreting pituitary adenomas. Such adenomas are occasionally difficult to identify on magnetic resonance imaging (MRI), and thorough endocrinological examination may be required to detect them. Inferior petrosal sinus (IPS) sampling (IPSS) has been the gold standard test for distinguishing CD from ectopic ACTH syndrome (EAS). However, IPSS is an invasive procedure, and proper catheterization is occasionally challenging due to anatomical variations. Thus, there have been ongoing debates regarding the necessity of this procedure. Here, we present our recent IPSS data derived from the analysis of 65 patients who were referred to us for possible CD between April 2018 and December 2020 after undergoing meticulous endocrinological testing. Even with detailed MRI, no obvious lesions were identified in 19 patients. IPSS performed on these 19 individuals identified an IPS-to-peripheral ACTH gradient in 15 of them. The four patients who lacked this gradient were subjected to a classical algorithm using concurrently measured prolactin levels, the results of which were consistent with their ultimately confirmed diagnoses: two true-positive and two true-negative diagnoses. These findings support the validity of the algorithm and demonstrate that the prolactin-adjusted IPS-to-peripheral ACTH ratio can improve the differentiation between CD and EAS. We had no false-negative results, but three patients were false-positive. Consequently, those three patients in which no apparent tumor was clarified during surgery could not have any endocrinological improvement postoperatively.

An algorithm to improve lateralization accuracy of inferior petrosal sinus sampling: procedural nuances for complex patterns of venous drainage. Patient series

BACKGROUND

Inferior petrosal sinus sampling (IPSS) is a useful technique in the diagnosis of Cushing’s disease (CD) when the imaging finding is negative or equivocal. Different authors have reported considerable variability in the ability to determine tumor laterality with IPSS. Here the authors present a retrospective case series of 7 patients who underwent IPSS using a systematic algorithm to improve lateralization accuracy by identifying optimal sampling sites on the basis of individual cavernous sinus drainage patterns in each patient.

OBSERVATIONS

Of the 7 patients identified, 6 were determined to have CD and subsequently underwent surgery. IPSS was accurate in all patients from whom laterality was predicted. Arterial and venous angiography were used to define cavernous sinus drainage patterns and determine optimal sampling sites. All patients who underwent surgery achieved hormonal cure.

LESSONS

All IPSS predictions of lateralization were correct when available, and all patients who underwent surgery achieved hormonal cure. Advances in angiographic techniques for identification of the site of primary drainage from the cavernous sinus and subsequent optimization of microcatheter placement may improve the ability to predict tumor laterality.

Inferior petrosal sinus sampling in Cushing's syndrome: usefulness and pitfalls

In patients with ACTH-dependent Cushing's syndrome (CS), the differentiation between Cushing's disease (CD) and ectopic ACTH secretion (EAS) can often be challenging. The traditionally used biochemical tests have limited diagnostic accuracy and imaging modalities may fail to detect the culprit lesion. Inferior petrosal sinus sampling (IPSS) was introduced more than 3 decades ago as a test with optimal diagnostic accuracy and has since become the gold standard in the differential diagnosis between CD and EAS. However, several, albeit rare, pitfalls may limit its diagnostic accuracy and awareness is needed to avoid incorrect interventions. Moreover, it is an invasive and demanding procedure, available in a limited number of centers worldwide. This review aims to critically present the usefulness and pitfalls of IPSS and define strategies for its optimal place in the contemporary management of CS.

The role of bilateral inferior petrosal sinus sampling in determining the preoperative localization of ACTH-secreting pituitary microadenomas in Cushing's disease: Experience of a tertiary center

INTRODUCTION

Bilateral inferior petrosal sinus sampling (BIPSS) is an important procedure in the diagnostic work-up of Cushing's syndrome (CS). In this study, we investigated the diagnostic performance of BIPSS in detecting the source of adrenocorticotropic hormone (ACTH) secretion in Cushing's disease (CD) without radiological evidence.

METHODS

Thirty-five consecutive patients who underwent BIPSS due to ACTH-dependent CS between 2010 and 2019 in our clinic and subsequently underwent transsphenoidal surgery were included. The indication for BIPSS was biochemically proven ACTH-dependent CS but normal or ≤6 mm pituitary lesion in pituitary magnetic resonance imaging (MRI). Corticotropin releasing hormone (CRH) stimulation was applied to all patients during the BIPSS procedure. BIPSS data, MRI results, pathological findings, and follow-up results were analyzed. The diagnostic performance of BIPSS was calculated.

RESULTS

A total of 35 patients, 6 (17%) males and 29 (83%) females, were included in the study. Pituitary MRI was normal in 12 (34.3%) and revealed lesions ≤ 6 mm in 23 (65.7%) patients. BIPSS lateralized the right side in 13 (37.1%) and left side in 18 (51.4%) patients, while no lateralization was observed in the remaining 4 (11.5%) patients. BIPSS showed lateralization in the same direction with pituitary adenoma in 21 (60%) patients before CRH injection and in 29 (83%) patients after CRH injection (p = 0.034). The sensitivity of the BIPSS procedure was 88%. Accurate localization of the pituitary lesion was more frequent when based on BIPSS results than on MRI (83% vs. 51%, P = 0.005).

CONCLUSION

BIPSS appears to be a valuable and safe diagnostic tool in patients who are diagnosed with CD biochemically but do not have clear radiological evidence of ACTH-producing lesion.

Pitfalls in Performing and Interpreting Inferior Petrosal Sinus Sampling: Personal Experience and Literature Review

CONTEXT

Inferior petrosal sinus sampling (IPSS) helps differentiate the source of ACTH-dependent hypercortisolism in patients with inconclusive biochemical testing and imaging, and is considered the gold standard for distinguishing Cushing disease (CD) from ectopic ACTH syndrome. We present a comprehensive approach to interpreting IPSS results by examining several real cases.

EVIDENCE ACQUISITION

We performed a comprehensive review of the IPSS literature using PubMed since IPSS was first described in 1977.

EVIDENCE SYNTHESIS

IPSS cannot be used to confirm the diagnosis of ACTH-dependent Cushing syndrome (CS). It is essential to establish ACTH-dependent hypercortisolism before the procedure. IPSS must be performed by an experienced interventional or neuroradiologist because successful sinus cannulation relies on operator experience. In patients with suspected cyclical CS, it is important to demonstrate the presence of hypercortisolism before IPSS. Concurrent measurement of IPS prolactin levels is useful to confirm adequate IPS venous efflux. This is essential in patients who lack an IPS-to-peripheral (IPS:P) ACTH gradient, suggesting an ectopic source. The prolactin-adjusted IPS:P ACTH ratio can improve differentiation between CD and ectopic ACTH syndrome when there is a lack of proper IPS venous efflux. In patients who have unilateral successful IPS cannulation, a contralateral source cannot be excluded. The value of the intersinus ACTH ratio to predict tumor lateralization may be improved using a prolactin-adjusted ACTH ratio, but this requires further evaluation.

CONCLUSION

A stepwise approach in performing and interpreting IPSS will provide clinicians with the best information from this important but delicate procedure.

Pituitary magnetic resonance imaging vs. bilateral inferior petrosal sinus sampling: comparison between non-invasive and invasive diagnostic techniques for Cushing's disease-a narrative review

Cushing's syndrome is a pathological clinical condition caused by an exposure of elevated cortisol levels over a long period of time. It is therefore essential to establish what the cause of hypercortisolism is. In most cases (about 80%) the pathological process is due to adrenocorticotropic hormone (ACTH), while in a minor part of the cases (about 20%) the cause is represented by a pathology of the adrenal glands and therefore not related to ACTH. Most patients with ACTH dependent Cushing's syndrome have a pituitary microadenoma; in the remaining cases (30%), the high level of cortisol is linked to an ectopic secretion of ACTH. Surgical removal of the pituitary adenoma represents the treatment of choice in Cushing's disease (CD) patients; it is therefore necessary to identify and precisely locate the pituitary tumour responsible for the secretion of ACTH. Adequate diagnostic information is very often, even with magnetic resonance imaging (MRI), and in these cases we rely on bilateral inferior petrosal sinuses sampling (BIPSS). This procedure is considered the gold standard method for the diagnosis, but like any other diagnostic method it is not free from erroneous results such as false positives or false negatives.

Cushing's Disease

In patients with Cushing's disease (CD), prompt diagnosis and treatment are essential for favorable long-term outcomes, although this remains a challenging task. The differential diagnosis of CD is still difficult in some patients, even with an organized stepwise diagnostic approach. Moreover, despite the use of high-resolution magnetic resonance imaging (MRI) combined with advanced fine sequences, some tumors remain invisible. Surgery, using various surgical approaches for safe maximum tumor removal, still remains the first-line treatment for most patients with CD. Persistent or recurrent CD after unsuccessful surgery requires further treatment, including repeat surgery, medical therapy, radiotherapy, or sometimes, bilateral adrenalectomy. These treatments have their own advantages and disadvantages. However, the most important thing is that this complex disease should be managed by a multidisciplinary team with collaborating experts. In addition, a personalized and individual-based approach is paramount to achieve high success rates while minimizing the occurrence of adverse events and improving the patients' quality of life. Finally, the recent new insights into the pathophysiology of CD at the molecular level are highly anticipated to lead to the introduction of more accurate diagnostic tests and efficacious therapies for this devastating disease in the near future.

Influence of inferior petrosal sinus drainage symmetry on detection of adenomas in Cushing's syndrome

BACKGROUND

Asymmetric inferior petrosal sinuses (IPS) are not infrequently encountered during bilateral IPS sampling. There is little data on whether IPS symmetry influences success in predicting the adenoma side in patients with ACTH-dependent Cushing's syndrome (CS).

OBJECTIVE

To assess the influence of IPS drainage patterns on detection of an adenoma in CS.

METHODS

Retrospective single-center cohort analysis reviewing records of patients with CS and negative MRI findings who subsequently underwent BIPSS.

RESULTS

BIPSS was performed in 38 patients with a mean age of 45±15 years. The overall technical success rate was 97% for bilateral cannulation. Asymmetric IPS were observed in 11 (39%) patients with Cushing's disease (CD). A side-to-side ACTH ratio was not significantly different between patients with symmetric outflow and those with asymmetric outflow at baseline (8.6±2.7 versus 16.4±6.0; P=0.45), but ratios were significantly different after ovine corticotropin-releasing hormone (oCRH) stimulation (6.0±2.5 versus 35.7±22.5; P=0.03). BIPSS correctly predicted the side of the adenoma in 25 (96%) patients with CD. Prediction was better when the venous outflow was symmetric (100%) rather than asymmetric (93%), although the difference was not significant (P=0.42). Remission from CS was achieved in 32 patients (87%), independent of the symmetry of IPS.

CONCLUSIONS

Bearing in mind the sample size of this audit, asymmetric IPS at least do not seem to diminish the accuracy of diagnosis of ACTH-dependent CS, nor do they influence the clinical outcome.

Prolactin-adjusted ACTH Ratio in Predicting Lateralization of ACTH Source During Simultaneous Bilateral Inferior Petrosal Sinus Sampling in Patients with Cushing's Disease

INTRODUCTION

Prolactin-adjusted adrenocorticotropic hormone (ACTH) ratio is used to improve the diagnostic accuracy of bilateral inferior petrosal sinus sampling (BIPSS) for lateralization of pituitary adenoma.

OBJECTIVE

To study the use of prolactin for successful catheterization during BIPSS, the role of prolactin-normalized ACTH ratio for confirmation of Cushing's disease (CD) and prolactin-adjusted ACTH ratio in predicting the lateralization.

PATIENTS AND METHODS

BIPSS was done in patients with CD; prolactin-adjusted ACTH ratio was compared with intersinus ACTH ratio, magnetic resonance imaging, and intraoperative findings for localization of pituitary adenoma. Histopathology was taken as "gold standard" for the diagnosis of CD.

RESULTS

Eight patients underwent BIPSS. All the patients underwent transsphenoidal surgery. All these patients had proper venous sampling during BIPSS as determined by inferior petrosal sinus (IPS):Peripheral prolactin ratio of ≥1.8. Prolactin-normalized ACTH ratio of ≥1.3 was achieved in all the eight patients, which was consistent with the diagnosis of CD. Concordance of intersinus ACTH ratio ≥1.4 with the intraoperative findings was found in five of eight (62.5%) patients depicting correct lateralization. Concordance of prolactin-adjusted ACTH ratio with intraoperative findings was found in four of eight (50%) patients. Seven of eight patients had concordance of intersinus ACTH ratio with prolactin-adjusted ACTH ratio.

CONCLUSION

Prolactin is a useful marker for successful catheterization, confirming the diagnosis of CD during BIPSS, and prolactin-adjusted ACTH ratio does not add to the accuracy of lateralization of pituitary adenoma compared with intersinus ACTH ratio.

Tumour lateralization in Cushing's disease by inferior petrosal sinus sampling with desmopressin

BACKGROUND

Bilateral inferior petrosal sinus sampling (IPSS) with corticotropin-releasing hormone (CRH) is currently the gold standard in the diagnosis of Cushing's disease (CD) and has also been used in tumour lateralization. Our objective was to determine the diagnostic value and lateralization accuracy of IPSS with desmopressin.

METHODS

We retrospectively analysed 91 patients with Cushing's syndrome who had either negative findings on pituitary dynamic enhanced magnetic resonance imaging (MRI) or nonsuppressed high-dose dexamethasone suppression tests (HDDST). Thin-slice thoracoabdominal computed tomography (CT) and octreotide receptor imaging of whole body were also negative to rule out ectopic adrenocorticotropin hormone (ACTH) syndrome. All patients went through IPSS with desmopressin. Afterwards, transsphenoidal pituitary surgery, light microscope pathology and immunohistological staining for ACTH were performed in all patients.

RESULTS

Diagnosis of CD. Among the 91 patients included, 90 were confirmed with CD, of whom 89 had positive IPSS findings, therefore the sensitivity was 98.9%. The one patient who was negative for CD also had negative IPSS findings, therefore the specificity was 100%. Tumour lateralization. Among the 51 patients who were ultimately diagnosed with CD and whose lateralization by IPSS and surgery was either left or right, 37 had IPSS lateralization in concordance with surgery, therefore the concordance rate was 72.5%. Patients in the concordant group had a higher frequency of right lateralization by surgery.

CONCLUSIONS

IPSS with desmopressin is a sensitive approach in the diagnosis of CD and has moderate accuracy in tumour lateralization, making it an alternative choice to IPSS with CRH.

Prolactin correction for adequacy of petrosal sinus cannulation may diminish diagnostic accuracy in Cushing's disease

OBJECTIVE

Petrosal venous prolactin concentrations have been promoted to improve the diagnostic accuracy of inferior petrosal sinus sampling (IPSS), beyond that achieved with ACTH measurement alone, in diagnosing a pituitary ACTH source and determining corticotrophinoma side (L/R). Our objective was to assess the effect of using prolactin to confirm adequacy of petrosal cannulation in a cohort of patients with ACTH-dependent Cushing's syndrome.

DESIGN

Retrospective cohort study.

PATIENTS

Thirteen patients with clinical and biochemical Cushing's syndrome who underwent IPSS.

MEASUREMENTS

Serum prolactin and ACTH in peripheral and inferior petrosal sinus blood before and after corticotrophin-releasing hormone (CRH) injection.

RESULTS

Thirteen consecutive patients were diagnosed with Cushing's disease using uncorrected ACTH ratios. The side of PRL excess was the same as the side of ACTH excess in all cases. Use of various published prolactin-related equations suggested that the ACTH non-dominant side was not cannulated in four, six or seven patients depending on the equation used. The equations generally decreased the central-to-peripheral gradient on the uncorrected ACTH dominant side, increased the central-to-peripheral gradient on the contralateral side and diminished or even reversed the ACTH intersinus gradient.

CONCLUSIONS

Consistent co-lateralisation of prolactin and ACTH in IPSS strongly suggests that prolactin cannot act as an independent guide to the diagnosis and lateralisation of Cushing's disease. All patients with Cushing's disease had a prolactin intersinus gradient towards the tumourous side of the pituitary, for likely biological reasons. PRL-corrected ACTH concentrations may threaten the sensitivity and specificity of IPSS in diagnosing Cushing's disease and conceal lateralisation.

AN INDIVIDUALIZED APPROACH TO THE EVALUATION OF CUSHING SYNDROME

Cushing syndrome (CS) is caused by chronic exposure to excess glucocorticoids. Early recognition and treatment of hypercortisolemia can lead to decreased morbidity and mortality. The diagnosis of CS and thereafter, establishing the cause can often be difficult, especially in patients with mild and cyclic hypercortisolism. Surgical excision of the cause of excess glucocorticoids is the optimal treatment for CS. Medical therapy (steroidogenesis inhibitors, medications that decrease adrenocorticotropic hormone [ACTH] levels or glucocorticoid antagonists) and pituitary radiotherapy may be needed as adjunctive treatment modalities in patients with residual, recurrent or metastatic disease, in preparation for surgery, or when surgery is contraindicated. A multidisciplinary team approach, individualized treatment plan and long-term follow-up are important for optimal management of hypercortisolemia and the comorbidities associated with CS.

ABBREVIATIONS

ACTH = adrenocorticotropic hormone; BIPSS = bilateral inferior petrosal sinus sampling; CBG = corticosteroid-binding globulin; CD = Cushing disease; CRH = corticotropin-releasing hormone; CS = Cushing syndrome; Dex = dexamethasone; DST = dexamethasone suppression test; EAS = ectopic ACTH syndrome; FDA = U.S. Food & Drug Administration; HDDST = high-dose DST; IPS/P = inferior petrosal sinus to peripheral; MRI = magnetic resonance imaging; NET = neuroendocrine tumor; PET = positron emission tomography; UFC = urinary free cortisol.

Surgical outcomes in patients with Cushing's disease: the Cleveland clinic experience

CONTEXT

Transsphenoidal surgery (TSS) to resect a pituitary adenoma is considered first-line treatment for patients with Cushing's disease (CD). Early, post-operative remission rates >80% are expected for patients with a microadenoma (≤ 10 mm) visible on magnetic resonance (MR) imaging.

OBJECTIVE

To report surgical outcomes and predictors of remission in a specialist center for patients with CD.

PATIENTS AND METHODS

Clinical data was obtained from a prospective CD database in addition to review of all electronic medical, laboratory and surgical patient records. Patients who underwent their first TSS by one neurosurgeon between 2004 and 2013, and had a minimum 1 year follow up, were evaluated.

RESULTS

One hundred and one consecutive patients with CD (73F, 28M) underwent TSS. Median (range) age and follow-up were 47 (15-87) and 4.33 (1-9.8) years, respectively. At surgery, 74 (73.2%) patients had a microadenoma, 27 a macroadenoma; six of the latter patients had a planned, subtotal resection to control neurological signs due to mass effect. Initial remission rates were: microadenoma, 89% (66/74); macroadenoma, 63% (17/27); and 81% (17/21) in those macroadenomas where complete surgical removal was anticipated. Initial non-remission occurred in 18 patients, ten macro- and eight microadenoma; six of 18 had residual disease on most recent follow up. Six (2 macro, 4 micro) of the 83 patients with initial remission have had late (>12 months) recurrence of hypercortisolism that required either repeat TSS or adjunctive therapy, three of whom have persistent hypercortisolism. Macroadenoma (p = 0.003) and tumor invasion beyond the pituitary and sella (p < 0.001) were associated with failure to obtain remission with the initial TSS and greater likelihood of late recurrence. Patients in whom no lesion was seen on neuroimaging had rates of initial remission (21/25 or 84%) and a similar late recurrence rate of 4% (1/25) in comparison with those with MR-visible microadenomas (3/49, or 6%).

CONCLUSIONS

A team-based approach, in a specialized pituitary center, can lead to initial and durable, long-term remission in patients with CD. The presence of a macroadenoma and tumor extension beyond the pituitary and sella were predictive of initial non-remission as well as risk of late recurrence.

Cushing's syndrome: a practical approach to diagnosis and differential diagnoses

Diagnosis of Cushing's syndrome (CS) and identification of the aetiology of hypercortisolism can be challenging. The Endocrine Society clinical practice guidelines recommends one of the four tests for initial screening of CS, namely, urinary-free cortisol, late night salivary cortisol, overnight dexamethasone suppression test or a longer low-dose dexamethasone suppression test, for 48 hours. Confirmation and localisation of CS requires additional biochemical and radiological tests. Radiological evaluation involves different imaging modalities including MRI with or without different radio-nuclear imaging techniques. Invasive testing such as bilateral inferior petrosal sinus sampling may be necessary in some patients for accurate localisation of the cause for hypercortisolism. This best practice review discusses a practical approach for the diagnostic evaluation of CS with a brief discussion on differential diagnoses, and cyclical CS, to enhance the skills of clinicians and laboratory personnel.

Bilateral inferior petrosal sinus sampling

Simultaneous bilateral inferior petrosal sinus sampling (BIPSS) plays a crucial role in the diagnostic work-up of Cushing's syndrome. It is the most accurate procedure in the differential diagnosis of hypercortisolism of pituitary or ectopic origin, as compared with clinical, biochemical and imaging analyses, with a sensitivity and specificity of 88-100% and 67-100%, respectively. In the setting of hypercortisolemia, ACTH levels obtained from venous drainage of the pituitary are expected to be higher than the levels of peripheral blood, thus suggesting pituitary ACTH excess as the cause of hypercortisolism. Direct stimulation of the pituitary corticotroph with corticotrophin-releasing hormone enhances the sensitivity of the procedure. The procedure must be undertaken in the presence of hypercortisolemia, which suppresses both the basal and stimulated secretory activity of normal corticotrophic cells: ACTH measured in the sinus is, therefore, the result of the secretory activity of the tumor tissue. The poor accuracy in lateralization of BIPSS (positive predictive value of 50-70%) makes interpetrosal ACTH gradient alone not sufficient for the localization of the tumor. An accurate exploration of the gland is recommended if a tumor is not found in the predicted area. Despite the fact that BIPSS is an invasive procedure, the occurrence of adverse events is extremely rare, particularly if it is performed by experienced operators in referral centres.

Recommendations of the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism for the diagnosis of Cushing's disease in Brazil

Although it is a rare condition, the accurate diagnosis and treatment of Cushing's disease is important due to its higher morbidity and mortality compared to the general population, which is attributed to cardiovascular diseases, diabetes mellitus and infections. Screening for hypercortisolism is recommended for patients who present multiple and progressive clinical signs and symptoms, especially those who are considered to be more specific to Cushing's syndrome, abnormal findings relative to age (e.g., spinal osteoporosis and high blood pressure in young patients), weight gain associated with reduced growth rate in the pediatric population and for those with adrenal incidentalomas. Routine screening is not recommended for other groups of patients, such as those with obesity or diabetes mellitus. Magnetic resonance imaging (MRI) of the pituitary, the corticotropin-releasing hormone (CRH) test and the high-dose dexamethasone suppression test are the main tests for the differential diagnosis of ACTH-dependent Cushing's syndrome. Bilateral and simultaneous petrosal sinus sampling is the gold standard method and is performed when the triad of initial tests is inconclusive, doubtful or conflicting. The aim of this article is to provide information on the early detection and establishment of a proper diagnosis of Cushing's disease, recommending follow-up of these patients at experienced referral centers. Arch Endocrinol Metab. 2016;60(3):267-86.

Cushing's disease: pathobiology, diagnosis, and management

Cushing's disease (CD) is the result of excess secretion of adrenocorticotropic hormone (ACTH) by a benign monoclonal pituitary adenoma. The excessive secretion of ACTH stimulates secretion of cortisol by the adrenal glands, resulting in supraphysiological levels of circulating cortisol. The pathophysiological levels of cortisol are associated with hypertension, diabetes, obesity, and early death. Successful resection of the CD-associated ACTH-secreting pituitary adenoma is the treatment of choice and results in immediate biochemical remission with preservation of pituitary function. Accurate and early identification of CD is critical for effective surgical management and optimal prognosis. The authors review the current pathophysiological principles, diagnostic methods, and management of CD.

Cushing's syndrome: epidemiology and developments in disease management

Cushing’s syndrome is a rare disorder resulting from prolonged exposure to excess glucocorticoids. Early diagnosis and treatment of Cushing’s syndrome is associated with a decrease in morbidity and mortality. Clinical presentation can be highly variable, and establishing the diagnosis can often be difficult. Surgery (resection of the pituitary or ectopic source of adrenocorticotropic hormone, or unilateral or bilateral adrenalectomy) remains the optimal treatment in all forms of Cushing’s syndrome, but may not always lead to remission. Medical therapy (steroidogenesis inhibitors, agents that decrease adrenocorticotropic hormone levels or glucocorticoid receptor antagonists) and pituitary radiotherapy may be needed as an adjunct. A multidisciplinary approach, long-term follow-up, and treatment modalities customized to each individual are essential for optimal control of hypercortisolemia and management of comorbidities.

The value of prolactin in inferior petrosal sinus sampling with desmopressin stimulation in Cushing's disease

Prolactin may reduce false-negative results in diagnosing Cushing's disease (CD) during inferior petrosal sinus sampling (IPSS). Prolactin normalization could improve the accuracy of IPSS in predicting adenoma lateralization in CD. However, none of the previous studies had involved the use of desmopressin during IPSS. Our objective was to examine the utility of prolactin measurement during IPSS with desmopressin stimulation. We conducted a retrospective analysis of 40 patients (including 31 females) with ACTH-dependent Cushing's syndrome who underwent IPSS between 2010 and 2013. Thirty-eight CD patients were partitioned into true positive (n = 35) and false negative (n = 3). The proportion of improper IPSS venous sampling defined by corresponding IPS:P (inferior petrosal sinus to peripheral) prolactin ratio <1.8 was significantly different between two groups (P = 0.004). Applying a prolactin-normalized ACTH IPS:P ratio >0.8 cutoff could increase the sensitivity of IPSS to 38/38 (100 %). Among the 31 patients with histopathologically proven adenoma localization, correct prediction of adenoma lateralization was obtained in 14/31 (45 %) patients by a peak intersinus ACTH gradient of ≥1.4 in baseline and was not improved by desmopressin stimulation. Left-right intersinus gradients of unilateral prolactin-adjusted ACTH IPS:P ratios could increase the correct prediction of adenoma lateralization to 20/31 (65 %) in baseline and 24/31 (77 %) (P = 0.006) after desmopressin stimulation, respectively. Prolactin is helpful to adjust negative results of IPSS with desmopressin stimulation. It may improve the accuracy in predicting adenoma lateralization in CD as well.

The role of inferior petrosal sinus sampling in ACTH-dependent Cushing's syndrome: review and joint opinion statement by members of the Italian Society for Endocrinology, Italian Society for Neurosurgery, and Italian Society for Neuroradiology

In the management of adrenocorticotropic hormone (ACTH)–dependent Cushing's syndrome, inferior petrosal sinus sampling (IPSS) provides information for the endocrinologist, the neurosurgeon, and the neuroradiologist. To the endocrinologist who performs the etiological diagnosis, results of IPSS confirm or exclude the diagnosis of Cushing's disease with 80%–100% sensitivity and over 95% specificity. Baseline central-peripheral gradients have suboptimal accuracy, and stimulation with corticotropin-releasing hormone (CRH), possibly desmopressin, has to be performed. The rationale for the use of IPSS in this context depends on other diagnostic means, taking availability of CRH and reliability of dynamic testing and pituitary imaging into account. As regards the other specialists, the neuroradiologist may collate results of IPSS with findings at imaging, while IPSS may prove useful to the neurosurgeon to chart a surgical course. The present review illustrates the current standpoint of these 3 specialists on the role of IPSS.

Preoperative Lateralization Modalities for Cushing Disease: Is Dynamic Magnetic Resonance Imaging or Cavernous Sinus Sampling More Predictive of Intraoperative Findings?

Objective To analyze whether cavernous sinus sampling (CSS) and dynamic magnetic resonance imaging (dMRI) are consistent with intraoperative findings in Cushing disease (CD) patients. Design Retrospective outcomes study. Setting Oregon Health & Science University; 2006 and 2013. Participants A total of 37 CD patients with preoperative dMRI and CSS to confirm central adrenocorticotropic hormone (ACTH) hypersecretion. Patients were 78% female; mean age was 41 years (at diagnosis), and all had a minimum of 6 months of follow-up. Main Outcome Measures Correlations among patient characteristics, dMRI measurements, CSS results, and intraoperative findings. Results All CSS indicated presence of CD. Eight of 37 patients had no identifiable tumor on dMRI. Three of 37 patients had no tumor at surgery. dMRI tumor size was inversely correlated with age (rs = - 0.4; p = 0.01) and directly correlated to intraoperative lateralization (rs = 0.3; p < 0.05). Preoperative dMRI was directly correlated to intraoperative lateralization (rs = 0.5; p < 0.002). CSS lateralization showed no correlation with intraoperative findings (rs = 0.145; p = 0.40) or lateralization observed on preoperative dMRI (rs = 0.17; p = 0.29). Postoperative remission rate was 68%. Conclusion dMRI localization was most consistent with intraoperative findings; CSS results were less reliable. Results suggest that small ACTH-secreting tumors continue to pose a challenge to reliable preoperative localization.

Ectopic ACTH-secreting pituitary adenomas within the sphenoid sinus

Ectopic pituitary adenomas are defined by the presence of adenomatous pituitary tissue outside the sella and distinctly separate from the pituitary gland. Ectopic ACTH-secreting pituitary adenomas (EAPAs) are a rare cause of Cushing's syndrome. Detecting these radiologically can prove difficult, in part, due to their typically small size and unpredictable anatomical location. In ACTH-dependent Cushing's syndrome, if, despite comprehensive testing, the source of excess ACTH remains occult (including negative work up for ectopic ACTH syndrome) thought should be given to the possibility of the patient harboring an EAPA. In most cases, ectopic ACTH pituitary adenomas within the sphenoid sinus will manifest with symptoms of hormonal excess, have an obvious sphenoid sinus mass on pre-operative imaging and will demonstrate resolution of hypercortisolism after surgical excision if located and removed. Twenty cases of EAPAs have been reported in the literature to date. This paper will review the current literature on all previously reported EAPAs within the sphenoid sinus in addition to the current case.

Is prolactin measurement of value during inferior petrosal sinus sampling in patients with adrenocorticotropic hormone-dependent Cushing's Syndrome?

Inferior petrosal sinus sampling (IPSS) is considered the gold standard test to distinguish between Cushing's disease (CD) and ectopic ACTH syndrome (EAS). Anomalous venous drainage, abnormal venous anatomy, and lack of expertise can lead to false-negative IPSS results and thereby misclassification of patients with ACTH-dependent Cushing's syndrome. Prolactin measurement during IPSS can improve diagnostic accuracy and decrease false negative results. A baseline prolactin inferior petrosal sinus to peripheral (IPS/P) ratio (ipsilateral to the dominant post-CRH ACTH IPS/P ratio) of 1.8 or more suggests successful catheterization during IPSS. Prolactin-normalized ACTH IPS/P ratios can then be used to differentiate between a pituitary and ectopic source of ACTH. Values ≤ 0.7 are suggestive of EAS and those ≥ 1.3 are indicative of CD, but the implication of values between 0.7 and 1.3 remains unclear and needs further investigation. Larger prospective studies are also needed for further evaluation of the role of contralateral prolactin IPS/P ratios, post- CRH prolactin values, and prolactin-adjusted ACTH inter-sinus ratios for tumor localization in CD.

Cushing's disease in 2012

The aim of this study was to review the literature published and the most important papers presented to meetings on Cushing's disease from October 2011 to September 2012. The selection has been performed according to the authors' criteria. Articles have been classified into five groups: quality of life and perception of the disease, clinical features and pathophysiology, comorbidity conditions, diagnosis, and treatment. The results and conclusions of each publication are discussed.

The lateralization accuracy of inferior petrosal sinus sampling in 501 patients with Cushing's disease

CONTEXT

It is often difficult to find an adenoma in patients with Cushing's disease (CD) whose preoperative magnetic resonance imaging (MRI) is normal. Better localizing modalities are needed.

OBJECTIVE

The aim of this study was to determine the accuracy of inferior petrosal sinus sampling (IPSS) in predicting adenoma lateralization.

DESIGN AND SETTING

We conducted a prospective observational study at a tertiary care clinical research center.

PATIENTS

A total of 501 consecutive patients (363 female) with confirmed ACTH adenomas and IPSS were included.

MAIN OUTCOME MEASURE

We measured the accuracy of IPSS to predict the intrasellar location of an adenoma.

RESULTS

IPSS confirmed a pituitary source of ACTH secretion in 491 patients (98%). All 10 patients with false-negative results had peak IPSS ACTH concentrations (before or after CRH) of < 400 pg/ml. Interpetrosal (side-to-side) ratios were ≥ 1.4 in 491 patients (98%). This ratio correctly predicted lateralization in 273 of 396 patients (positive predictive value = 69%) with a lateral adenoma. Left-sided IPSS lateralization (P = .008) and consistent lateralization before and after CRH administration (P = .02) were associated with enhanced accuracy. When positive, preoperative MRI correlated with adenoma location in 171 of 201 patients (positive predictive value = 86%).

CONCLUSIONS

Potential false-negative results, the most common type of diagnostic error with IPSS for the differential diagnosis of CS, can be identified by peak IPSS ACTH values < 400 pg/ml. When MRI is normal, IPSS can be used to guide surgical exploration in patients with negative preoperative imaging. However, because of the limited accuracy of lateralization, thorough exploration of the pituitary gland is required when an adenoma is not readily discovered based on predicted location.