Cyclical Cushing's syndrome first diagnosed after pituitary surgery: a trap for the unwary

Diagnostic challenges in cyclic Cushing's syndrome: a systematic review

Cyclic Cushing's syndrome is a subentity of Cushing's syndrome in which phases of biochemical hypercortisolism (peaks) are followed by spontaneous periods of physiological or even hypocortisolaemic cortisol secretion (troughs). To identify common features of cyclic Cushing's syndrome, we systematically reviewed single case reports and case series in MEDLINE from database inception to Oct 10, 2022, and identified 707 articles, of which 149 articles were assessed for eligibility and 118 articles (covering 212 cases) were included in the analysis. Pituitary tumours accounted for 67% of cases of cyclic Cushing's syndrome (n=143), ectopic tumours for 17% (n=36), and adrenal tumours for 11% (n=23). Occult tumours accounted for 2% of cases (n=4), and 3% of cases were unclassified (n=6). We compared the clinical symptoms and comorbidities of patients with cyclic Cushing's syndrome with those of patients with non-cyclic Cushing's syndrome and observed no major difference. In adrenocorticotropic hormone (ACTH)-dependent cyclic Cushing's syndrome, bilateral inferior petrosal sinus sampling had a positive (ie, true pituitary) and negative (ie, true ectopic) predictive value of 100% when performed during periods of hypercortisolism, versus a positive predictive value of 73% and a negative predictive value of 86% when performed, irrespective of cortisolaemic status. Overall, 6% of patients (n=12) with cyclic Cushing's syndrome had unnecessary surgery due to misclassification. Remission rates were significantly lower and the time to remission significantly longer in patients with cyclic Cushing's syndrome compared with patients with non-cyclic Cushing's syndrome (p<0·001). Variations in biochemical test results due to unpredictable cycle duration and frequency might cause diagnostic challenges resulting in misdiagnoses and missed diagnoses.

Remission in Cushing's disease is predicted by cortisol burden and its withdrawal following pituitary surgery

AIM

To ascertain the predictors of remission and relapse in patients of Cushing's disease (CD) undergoing pituitary transsphenoidal surgery (TSS).

METHODS

Patients with CD subjected to TSS over 35 years at a tertiary care center were included. Patients were grouped into remission and persistent disease at 1 year after surgery, and were further followed up for relapse. Demographic, clinical, biochemical, histological, radiological and post-operative follow-up parameters were analyzed.

RESULTS

Of the 152 patients of CD, 145 underwent TSS. Remission was achieved in 95 (65.5%) patients at 1 year. Patients in remission had shorter duration of symptoms prior to presentation (p = 0.009), more frequent presence of proximal myopathy (p = 0.038) and a tumor size of < 2.05 cm (p = 0.016) in comparison to those with persistent disease. Post-TSS, immediate post-operative 0800-h cortisol (< 159.85 nmol/L; p = 0.001), histological confirmation of tumor (p = 0.045), duration of glucocorticoid replacement (median 90 days; p = 0.001), non-visualization of tumor on MRI (p = 0.003), new-onset hypogonadism (p = 0.001), 3-month 0800-h cortisol (< 384.9 nmol/L; p = 0.001), resolution of diabetes (p = 0.001) and hypertension (p = 0.001), and recovery of hypothalamic-pituitary-adrenal axis (p = 0.018) favored remission. In logistic regression model, requirement of glucocorticoid replacement (p = 0.033), and resolution of hypertension post-TSS (p = 0.003) predicted remission. None of the parameters could predict relapse.

CONCLUSION

The study could ascertain the predictors of remission in CD. Apart from the tumor characteristics, surgical aspects and low post-operative 0800-h cortisol, the results suggest that baseline clinical parameters, longer glucocorticoid replacement, and resolution of metabolic complications post-TSS predict remission in CD. Long-term follow-up is essential to look for relapse.

Treatment challenges in pediatric Cushing's disease: Review of the literature with particular emphasis on predictive factors for the disease recurrence

Cushing's disease (CD) is a rare endocrine condition caused by a corticotroph pituitary tumor that produces adrenocorticotropic hormone. The current state of knowledge of CD treatment is presented in this article including factors that can be helpful in predicting remission and/or recurrence of the disease. The primary goals in CD treatment are quick diagnosis and effective, prompt treatment as the persistent disease is associated with increased morbidity and mortality. Cooperation of a team consisting of experienced pediatrician/adult endocrinologist, neuroradiologist, transsphenoidal neurosurgeon and (if necessary) radiotherapist contribute to the best treatment effects.

Cyclic Cushing's Disease in the Prepubertal Period-A Case Report and Review of Literature

Background: Cyclic Cushing's disease (CD) has been described in about 15% of adult patients with CD. In the pediatric population, diagnosis of CD is rare and cyclic presentations of the disease are not adequately understood or described. Moreover, prepubertal patients usually do not present with the typical signs and symptoms of CD, which can obscure or delay diagnosis. In this paper, we report a case of cyclic CD in a prepubertal age girls whose etiology was a pituitary corticotropinoma. Case presentation: A Caucasian 7.8 year old girl was admitted to pediatric endocrinology for the evaluation of short stature and prior obesity. The patient remained overweight despite significant lifestyle modifications, resulting in 6 kg weight loss during the prior 6 months. The physical exam was notable for precocious adrenarche and thelarche, but difficult to differentiate from steatomastia. Hypothalamo-pituitary-adrenal axis diagnostics, including single diurnal excretion of urinary cortisol, morning ACTH, and serum cortisol levels, were all within normal limits, and MRI of the pituitary gland showed no deviations at this time. Because of the clinical suspicion of cyclic hypercortisolemia, she was referred to our outpatient clinic for follow-up. After 6 months, the patient returned with rapid weight gain, accompanied by nocturnal anxiety, exacerbation of depressive behavior, insomnia and excessive sweating, and was readmitted to the ward for testing. Standard diagnostics confirmed CD and repeat MRI at 8.6 years old showed a microadenoma of 3 × 4 mm in the right side of the anterior pituitary gland. Histopathologic examination described an atypical, densely-granulated pituitary corticotroph adenoma with Ki-67 expression above 3%. Conclusion: Cyclic presentations of CD in the prepubescent age group could cause difficulties in diagnosis because of atypical signs and symptoms, which can be absent in the remission phase. Decreases in height percentiles and velocities obtained from the growth chart, as well as fluctuations in weight, and signs of androgenization can allow the clinician to suspect cycling CD in prepubertal patients. Confirmation of cyclic CD diagnosis is only possible during periods of relapse (hypercortisolemic state) and should be investigated according to the current diagnostic standard.

Two types of ectopic Cushing syndrome or a continuum? Review

BACKGROUND

Two types of ectopic Cushing syndrome (ECS) are described: ECS associated with aggressive neoplasms, and ECS with indolent and occult tumors, however, there is a lack of studies that thoroughly review their characteristics.

METHODS

A systematic review was carried out on PUBMED of all the papers about the ECS, in order to better define the types of this subcategory of Cushing's syndrome, highlighting the differential aspects between these subgroups.

RESULTS

It was found that in 50% of cases the prototypic "aggressive" ECS is caused by small cell lung carcinomas (SCLC). In these cases, the clinical presentation may be atypical, predominating the signs and symptoms derived from the protein catabolism. Cortisol and ACTH levels are extremely high, the clinical presentation is abrupt (< 3-6 months) and the tumor is usually advanced, being impossible a curative treatment. On the other hand, "indolent" ECS is mainly represented by carcinoid tumors (CT). In these cases the clinical presentation overlaps enormously with that of Cushing's disease (CD). Cortisol and ACTH levels are slightly elevated, the clinical presentation is progressive (> 6 months) and the prognosis is usually good, and a curative treatment is possible in about 75% of the cases.

CONCLUSION

Although there is no absolute differentiation between the two extremes of ECS, a classification could be established in two groups, guided by its clinical and biochemical characteristics, and mainly by the type and stage of the ACTH-secreting tumor. However, a small percentage of tumors do not fit in this simple grouping, and may present both phenotypes or an intermediate one.

Characterization of cyclic Cushing's disease using late night salivary cortisol testing

OBJECTIVE

To characterize a cohort of patients with cyclic Cushing's disease (CD) in comparison with noncyclic CD using late night salivary cortisol (LNSC) and examine the diagnostic sensitivity of LNSC in comparison with that of 24-hour urine-free cortisol (UFC) in this population.

DESIGN

Retrospective study of patients with CD seen in our institution between 2008 and 2017.

PATIENTS

A total of 205 patients, including 17 (8%) with cyclic CD (based on a minimum of 3 peaks and 2 troughs in cortisol levels). In a secondary analysis, 38 patients (19%) with cyclic CD were identified (based on a criterion of at least 2 peaks and 1 trough).

MEASUREMENTS

Data on presentation, laboratory tests and outcomes were extracted. The diagnostic sensitivity of LNSC vs UFC in establishing cyclic CD was calculated. Kaplan-Meier analyses of recurrence after transsphenoidal pituitary surgery (TSS) were performed.

RESULTS

The interval between presentation and TSS was significantly longer in patients with cyclic CD (P < .0001) in comparison with those with noncyclic CD. The sensitivity of LNSC in establishing cyclic CD was 88% and was higher than that of UFC (12%, P = .007). There were no differences in remission and recurrence rates between patients with cyclic CD and those with noncyclic CD.

CONCLUSIONS

Patients with cyclic CD account only for a minority of those with CD, but may require a lengthier diagnostic evaluation. The use of LNSC on multiple occasions provides a more sensitive method of detecting cyclic CD than UFC. Outcomes of TSS in cyclic CD are comparable to those with noncyclic disease.

Routine Screening for Cushing's Syndrome Is Not Required in Patients Presenting with Obesity

Background. Cushing's syndrome (CS) is a relatively unusual condition that resembles many of the phenotypic features of obesity. Our aim was to evaluate the frequency of CS in obese patients. Materials and Methods. This study included 354 consecutive patients (87.9% female, age 37.8 ± 13.4 years) who presented with simple obesity. All the patients were evaluated for the clinical signs of CS. Lipid parameters, fasting glucose (FPG) and insulin, 75 gr oral glucose tolerance test, basal cortisol and ACTH were measured. 1 mg overnight DST was performed. Results. The mean weight of the patients was 102.4 ± 20.1 kg and BMI 40 ± 7.35 kg/m². 34.5% of the patients were hypertensive. 36.2% of the patients had central obesity, 72% dorsocervical fat accumulation, 28.8% abdominal striae and 23.2% acne. 49.4% of the women had hirsutism. 46.5% had prediabetes and 12.0% had type 2 diabetes, 72.6% had dyslipidemia. The mean cortisol and ACTH levels were as follows: 9.28 ± 3.53 μg/dL and 17.02 ± 10.43 pg/mL. Seven patients failed to suppress plasma cortisol to less than 1.8 μg/dL. Biochemical confirmation tests were performed in these patients and 2 of them were diagnosed glucocorticoid-secreting adrenal adenoma. Conclusions. Routine screening for CS in obese patients is not required.

What is the best approach to suspected cyclical Cushing syndrome? Strategies for managing Cushing's syndrome with variable laboratory data

Cyclical Cushing's syndrome is a pattern of hypercortisolism in which the biochemistry of cortisol production fluctuates rhythmically. This syndrome is often associated with fluctuating symptoms and signs. It is now being increasingly recognized. The phenomenon is important because it can, if not recognized, lead to errors in diagnosis and differential diagnosis of the syndrome and in assessment of therapeutic outcomes. The techniques and criteria, protocols and dynamic biochemical tools to detect cycling in patients with hypercortisolism are discussed as are the strategies for diagnosing and managing this important subgroup of patients with hypercortisolism.

Delayed remission after transsphenoidal surgery in patients with Cushing's disease

BACKGROUND

Transsphenoidal surgery (TSS) is the treatment of choice for Cushing's disease (CD). Postoperative hypercortisolemia mandates further therapy.

OBJECTIVE

The aim of the study was to characterize patients without immediate postoperative remission who have a delayed decrease to normal or low cortisol levels without further therapy.

DESIGN AND SETTING

A retrospective case series was conducted at three tertiary care centers.

PATIENTS AND INTERVENTION

We reviewed the records of 620 patients (512 females, 108 males; mean age, 38 +/- 13 yr) who underwent transsphenoidal pituitary surgery for CD between 1982 and 2007.

RESULTS

Outcomes were classified into the following three groups based upon the postoperative pattern of cortisol testing: group IC (immediate control) included 437 of the 620 patients (70.5%) with hypocortisolism and/or cortisol normalization throughout the postoperative follow-up; group NC (no control) included 148 of 620 patients (23.9%) with persistent hypercortisolism; and group DC (delayed control) included 35 of 620 patients (5.6%) who had early elevated or normal UFC levels and developed a delayed and persistent cortisol decrease after an average of 38 +/- 50 postoperative days. The total rate of recurrence was 13% at a median follow-up time of 66 months after TSS; the cumulative rate of recurrence at 4.5 yr was significantly higher in group DC vs. group IC (43 vs. 14%; P = 0.02).

CONCLUSIONS

Hormonal assessment in the immediate postoperative period after TSS for CD may be misleading because delayed remission can occur in a subset of patients. Expectant management and retesting may spare some patients from unnecessary further treatment. Optimal timing to determine the need for further therapy after TSS remains to be determined.

Contemporary issues in pituitary disease: case-based management update

Since 2005, the Cleveland Clinic Foundation has held an annual symposium addressing contemporary issues in pituitary disease. The faculty includes Cleveland Clinic Foundation staff, physicians and invited specialists, and the presentations are case-based with frequent audience response in order to be of real value in terms of the issues that may occur in day-to-day clinical practice relating to pituitary disease. This brief meeting report summarizes the key points arising from this interactive format. We feel it is worth pointing out that re-emphasizing 'old truths' is always an essential and valid aspect of any symposium addressing contemporary issues.

The prevalence and characteristic features of cyclicity and variability in Cushing's disease

OBJECTIVE

Cyclical Cushing's syndrome may render the diagnosis and management of Cushing's disease difficult. The aim of the present study was to investigate the prevalence of cyclicity and variability in patients with Cushing's disease, and to identify putative distinctive features.

DESIGN

Retrospective case-note study.

METHODS

We analysed the case records of 201 patients with Cushing's disease in a retrospective case-note study. Cyclicity was considered as the presence of at least one cycle, defined as a clinical and/or biochemical hypercortisolaemic peak followed by clinical and biochemical remission, followed by a new clinical and/or biochemical hypercortisolaemic peak. The fluctuations of mean serum cortisol levels, as assessed by a 5-point cortisol day curve, defined the variability.

RESULTS

Thirty (14.9%; 26 females) patients had evidence of cyclicity/variability. 'Cycling' patients were older but no difference in sex or paediatric distribution was revealed between 'cycling' and 'non-cycling' patients. The median number of cycles was two for each patient, and 4 years was the median intercyclic period. A trend to lower cure rate post-neurosurgery and lower adenoma identification was observed in 'cycling' compared with 'non-cycling' patients. In multivariate analysis, older patients, longer follow-up, female sex and no histological identification of the adenoma were associated with an increased risk of cyclic disease.

CONCLUSIONS

This large population study reveals that cyclicity/variability is not an infrequent phenomenon in patients with Cushing's disease, with a minimum prevalence of 15%. Physicians should be alert since it can lead to frequent problems in diagnosis and management, and no specific features can be used as markers.

Role for postoperative cortisol response to desmopressin in predicting the risk for recurrent Cushing's disease

In the early postoperative period of Cushing's disease patients, desmopressin may stimulate ACTH secretion in the remnant corticotrophic tumour, but not in nontumour suppressed cells.

OBJECTIVE

The aim of this study is to evaluate the serum cortisol responses to desmopressin after pituitary surgery, establishing an optimal cut-off for absolute increment (Delta) of serum cortisol (F) suitable to predict recurrence risk.

DESIGN

Retrospective case record study.

PATIENTS

Fifty-seven Cushing's disease patients submitted to pituitary surgery and desmopressin stimulation in the early postoperative with a long-term follow-up (20-161 months) were studied.

METHODS AND MEASUREMENTS

Serum cortisol levels after desmopressin test (10 microg i.v.) 15-30 days after adenomectomy were used to determine DeltaF (absolute increment of F: F peak - F baseline). Sensitivity and specificity of DeltaF were calculated and a ROC curve was performed to establish an optimal cut-off for DeltaF to predict recurrence risk.

RESULTS

Fifteen patients had immediate postoperative failure (basal F > 165 nmol/l; 6 microg/dl) and one patient was lost during the follow-up. Forty-one patients achieved initial remission and were followed-up. Five of 11 patients who recurred had DeltaF > 193 nmol/l (7 microg/dl), but none of 30 patients who remained in prolonged remission showed DeltaF > 193 nmol/l after postoperative desmopressin stimulation.

CONCLUSIONS

Persistence of cortisol response (DeltaF > 193 nmol/l) to desmopressin in the early postoperative period can help to identify Cushing's disease patients with initial remission who present risk for later recurrence.

Screening and diagnosis of Cushing's syndrome

Cushing's syndrome (CS) results from sustained pathologic hypercortisolism. The clinical features are variable and the most specific features for CS include abnormal fat distribution, particularly in the supraclavicular and temporal fossae, proximal muscle weakness, wide purple striae, and decreased linear growth with continued weight gain in a child. Clinical presentation of CS can be florid and in this case the diagnosis is usually straightforward. However, the diagnosis can be difficult particularly in states of mild or cyclical or periodical hypercortisolism. Several tests based on the understanding of the physiologic characteristics of the hypothalamic-pituitary-adrenal axis have been used extensively to confirm the diagnosis of Cushing's syndrome, but none has proven fully capable of distinguishing all cases of CS from normal and/or pseudo-Cushing individuals. Three first-line diagnostic tests are currently used to screen for CS: measurement of free cortisol in 24-hour urine (UFC), cortisol suppressibility by low doses of dexamethasone (DST), and assessment of cortisol circadian rhythm using late-night serum and/or salivary cortisol. This paper discusses the effectiveness regarding best cut-off values, the sensitivity and the specificity of these tests to screen for CS. Late-night salivary cortisol appears to be the most useful screening test. UFC and DST should be performed to provide further confirmation of the diagnosis.

Cyclical Cushing's syndrome: an update

PURPOSE OF REVIEW

This article reviews the features of cyclical hypercortisolism. This syndrome was once considered to be very rare but is now being increasingly recognized.

RECENT FINDINGS

Either true cycles or the variant of episodic and fluctuating levels of hypercortisolism can lead to considerable clinical dilemmas, which are discussed. The review details possible pathophysiological mechanisms and the effects of centrally acting drugs.

SUMMARY

Cyclical Cushing's syndrome is a pattern of hypercortisolism in which the biochemistry of cortisol production fluctuates rhythmically. This syndrome is often associated with fluctuating symptoms and signs. This type of case was initially thought to be rare. It has, however, recently been recognized as occurring much more frequently. The phenomenon is important because it can, if not recognized, lead to errors in diagnosis and differential diagnosis of the syndrome and in assessment of therapeutic outcomes. All of these can have very serious clinical consequences. Clinical researchers, including ourselves, have developed criteria, protocols and dynamic biochemical tools to detect cycling in patients with hypercortisolism. Unfortunately, the mechanisms causing the abnormal pathophysiology have not been well elucidated but some recent insights have been gained. The review discusses strategies for diagnosing and managing this important subgroup of patients with hypercortisolism.

An instructive case suggesting cyclical primary hyperparathyroidism

We report an instructive case of primary hyperparathyroidism in which cyclical secretion of PTH may have caused repeated hypercalcemic crises followed by temporary remission with a spontaneous drop in PTH. A 64-year-old man was admitted to our hospital twice with severe hypercalcemic crisis (corrected calcium (cCa) 15.0 mg/dl and 16.7 mg/dl) accompanied by an increase in intact PTH (220 pg/ml and 470 pg/ml). During both events, the serum PTH values spontaneously dropped followed by remission of the hypercalcemia. The tumor, detected at the left-upper side, showed neither vascularity on ultrasound examination nor washout delay on MIBI scintigraphy, suggesting that two parathyroid adenoma infarctions had occurred. Cervical exploration was undertaken. The histopathological examinations confirmed that the tumor was parathyroid adenoma. Contrary to our expectation, however, it did not reveal necrotic tissue that would indicate recent infarction. The findings in this case may be explained by cyclical secretion of PTH from a parathyroid adenoma. Although cyclical Cushing's syndrome is well known, to our knowledge this is the first documented case suggesting cyclical primary hyperparathyroidism.

Long-term remission rates after pituitary surgery for Cushing's disease: the need for long-term surveillance

OBJECTIVE

There have been a few reports on long-term remission rates after apparent early remission following pituitary surgery in the management of Cushing's disease. An undetectable postoperative serum cortisol has been regarded as the result most likely to predict long-term remission. Our objective was to assess the relapse rates in patients who underwent transsphenoidal surgery in order to determine whether undetectable cortisol following surgery was predictive of long-term remission and whether it was possible to have long-term remission when early morning cortisol was measurable but not grossly elevated. Endocrinological factors associated with late relapse were also studied.

PATIENTS

We reviewed the long-term outcome in 63 patients who had pituitary surgery for the treatment of Cushing's disease between 1979 and 2000.

MEASUREMENTS

Case notes were reviewed and the current clinical and biochemical status assessed. Our usual practice was that early after the operation, an 08:00 h serum cortisol was measured 24 h after the last dose of hydrocortisone. This was followed by a formal low-dose dexamethasone suppression test. Current clinical status and recent 24-h urinary free cortisol values were used as an index of activity of the Cushing's disease. If there was evidence suggesting relapse, a low-dose dexamethasone suppression test was performed. In many patients, sequential collections of early morning urine specimens for urinary cortisol to creatinine ratio were also performed in an attempt to diagnose cyclical and intermittent forms of recurrent hypercortisolism. We did this if there was conflicting endocrine data, or if patients were slow to lose abnormal clinical features.

RESULTS

Mean age at diagnosis was 40.3 years (range 14-70 years). Mean follow-up up time was 9.6 years (range 1-21 years). Forty-five patients (9 males/36 females) achieved apparent remission immediately after surgery and were subsequently studied long term. Of these 45 patients, four have subsequently died while in remission from hypercortisolism. Ten of the remaining 41 patients have relapsed. Of those 10, six demonstrated definite cyclical cortisol secretion. Two of the 10 had undetectable basal serum cortisol levels in the immediate postoperative period. Thirty-one patients are still alive and in remission. Fourteen (45%) of the 31 who remained in remission had detectable serum cortisol levels (> 50 nmol/l) immediately postoperatively, and remain in remission after a mean of 8.8 years. Our relapse rate was therefore 10/45 (22%), after a mean follow-up time of 9.6 years, with mean time to relapse 5.3 years.

CONCLUSIONS

The overall remission rate of 56% (35/63) at 9.6 years follow-up is disappointing and merits some re-appraisal of the widely accepted principle that pituitary surgery must be the initial treatment of choice in pituitary-dependent Cushing's syndrome. Following pituitary surgery, careful ongoing expert endocrine assessment is mandatory as the incidence of relapse increases with time and also with increasing rigour of the endocrine evaluation. A significant number of our patients were shown to have relapsed with a cyclical form of hypercortisolism.

Cyclic Cushing's disease with paradoxical response to dexamethasone

Cyclic Cushing's disease is an unusual disorder characterised by ACTH-dependent periodical increase of serum cortisol levels, clinically accompanied by peripheral edema, abnormalities of cardiac rhythm and hypokalemia. The condition may be unrecognised for years, since the typical features of Cushing's disease are usually absent due to the intermittent and brief duration of cortisol hypersecretion. We describe the case of a 42-yr-old man with Cyclic Cushing's disease due to an ACTH-producing pituitary macroadenoma, who presented two episodes of hypercortisolism in a 3-yr-period, clinically characterised by peripheral edema, hypokalemia and arrhythmia. The diagnosis was suspected because of a paradoxical increase of plasma ACTH and cortisol after dexamethasone administration during an asymptomatic period and was confirmed by pituitary imaging and by final histology after transphenoidal resection of the pituitary adenoma. After surgery, the patient resumed a normal pituitary-adrenal function with restoration of the normal ACTH and cortisol suppression after dexamethasone. Cyclic Cushing's disease should be considered in the differential diagnosis of several conditions characterised by recurrent episodes of idiopathic edema, hypokalemia or unexplained cardiac arrhythmia. In such patients, the pituitary-adrenal axis should be tested possibly during the acute phase of their disease or using the dexamethasone suppression test during asymptomatic intervals.

Periodic secretion of adrenocorticotropin in a patient with Cushing's disease manifested during pregnancy

We report the case of 19-year-old woman with cyclical Cushing's disease, in whom plasma adrenocorticotropin (ACTH) was secreted periodically after her first pregnancy. Since the 33rd week of pregnancy, hypertension and proteinuria became clinically remarkable. She gave normal birth at 36th week of pregnancy; however she continued to gain body weight even after delivery and developed typical Cushingoid features. Her ACTH secretion lacked normal daily fluctuation but exhibited periodic change during 1-year observation, showing 119 pg/ml, 34.6 pg/ml and 115 pg/ml at the 4th, 7th and 13th months after delivery. Plasma ACTH levels were increased by corticotropin releasing hormone and metyrapone, while low-dose dexamethasone suppressed cortisol secretion. Gel filtration analysis of the patient's plasma detected big ACTH molecules being eluted with a peak of authentic 1-39 ACTH. Cranial magnetic resonance imaging revealed a 1-cm pituitary mass in right cavernous sinus. The pituitary tumor was removed by transsphenoidal surgery at 13th month after delivery and was pathologically compatible with ACTH-producing pituitary adenoma by immunohistochemistry. This case includes clinically rare subsets of Cushing's syndrome showing periodic ACTH secretion and aberrant ACTH molecules.

Dexamethasone infusion testing in the diagnosis of Cushing's syndrome

Cushing's syndrome and its various aetiologies is a markedly difficult diagnosis to make given its subtle signs, sometime cyclical nature, and the lack of a single definitive diagnostic test. Although a great variety of diagnostic tests have been developed to assist in the diagnosis, even with the best clinical acumen, biochemistry and medical imaging the diagnosis can remain elusive. The long low and high dose oral dexamethasone suppression test is cumbersome, costly and often requiring an extended inpatient stay. The utility of the dexamethasone suppression test would be greatly enhanced if it could be performed as a short outpatient procedure. In this study we sought to confirm and refine the clinical utility of the high dose 4 mg intravenous dexamethasone suppression test as an alternative diagnostic test for Cushing's syndrome. There were a total of 31 subjects: 8 patients with proven pituitary Cushing's disease, 3 with primary adrenal tumors, 10 with pseudo-Cushing's syndrome and 10 healthy controls. All subjects with pseudo-Cushing's syndrome suppress serum cortisol at +5 and at +24 hours. In subjects with pituitary Cushing's disease, 7 out of 8 (88%) had serum cortisol suppressed at +5 hours but rebounded at +24 hours to at least 70% of the original serum level. Primary adrenal tumors showed a pattern of non-suppression throughout. The 4 mg intravenous dexamethasone suppression test is excellent in ruling out pseudo-Cushing's syndrome. This test is much simpler and more convenient than the oral dexamethasone suppression test in confirming clinical suspicion of pituitary Cushing's disease.

Cyclical Cushing's syndrome in a patient with a bronchial neuroendocrine tumor (typical carcinoid) expressing ghrelin and growth hormone secretagogue receptors

A 56-yr-old woman was referred with a diagnosis of Cushing's disease. Hypertension and severe hypokalemia were present and high urinary free cortisol/cortisone ratio was detected, raising a suspicion of an ectopic ACTH syndrome. Inferior petrosal sinus sampling, thoracic computed tomography, and octreotide scans were negative. Remission and relapse periods lasting 3-4 months were observed during the 3.5 yr of follow-up. Finally a thoracic computed tomography scan showed a basal paracardic nodule in the left lung. After surgery, a well-differentiated neuroendocrine tumor (typical bronchial carcinoid) was diagnosed, staining positively for ACTH. RT-PCR revealed expression of proopiomelanocortin, CRH receptor, and V3 vasopressin receptor. Somatostatin receptor type 1, 2, 3, and 5 mRNA was detected only in tumoral tissue. Interestingly, we observed the simultaneous presence of ghrelin and both GH secretagogue (GHS) receptors (1a and 1b) mRNA in tumoral tissue but not in the normal lung. This finding correlates with the in vivo ACTH hyperresponsiveness to hexarelin (a GHS). This is the first report of a cyclical ectopic ACTH-secreting tumor with an in vivo ACTH response to hexarelin coupled with the tumoral expression of ghrelin and GHS receptors. This finding might imply an autocrine/paracrine modulatory effect of ghrelin in bronchial ACTH-secreting tumors.

Clinical and biochemical evaluation of Cushing's syndrome

Over the past decade, several advances have been made in our understanding of the molecular pathogenesis of pituitary adenomas, and novel diagnostic tests for the diagnosis and differential diagnosis of Cushing's syndrome have been developed. Although established in the late 1970s, measurement of UFC has emerged as the most sensitive and specific test to screen for and confirm the presence of Cushing's syndrome. The combined CRH/DST is potentially a useful adjunct in patients with probable pseudo-Cushing's syndrome and borderline elevated urinary cortisol levels. Improved assays for circulating ACTH levels are now used as the first test in differentiating ACTH-dependent from ACTH-independent sources. HDDST with the revised reference ranges for UFC currently remains the primary test for differentiating pituitary from ectopic ACTH secretion. However, the CRH test may replace the HDDST in the foreseeable future because of its lower rate of false-positive and false-negative results. IPSS has been established as an integral part of the evaluation of patients with suspected Cushing's disease and no conclusive (> 0.8 to 1 cm) pituitary adenoma. Advances in the radiolabeling of small peptides, such as somatostatin analogs, may facilitate the search for occult ectopic sources.

Diagnostic difficulties in periodic Cushing's syndrome

A 22-year-old black woman presented with symptoms suggestive of Cushing's syndrome three years after chemotherapy for a presumed teratoma with cervical lymphadenopathy. Initially, the absence of clinical signs and the demonstration of two normal 24 h urinary free cortisols appeared to exclude the diagnosis, but an ectopic adrenocorticotropin-producing thymic carcinoid was subsequently removed surgically. Cushing's syndrome due to ectopic adrenocorticotropin production can be difficult to diagnose, particularly if there is periodic hormonogenesis.

Intermittent Hypercortisolism: A Disorder Strikingly Prevalent After Hypophysial Surgical Procedures

OBJECTIVE

To determine the frequency of intermittent hypercortisolism in a consecutive series of patients with Cushing's disease who underwent hypophysial surgical treatment.

METHODS

Thirty-three patients with hypercortisolism of central origin underwent follow-up at approximately annual intervals for prolonged periods after a transsphenoidal pituitary surgical procedure. Clinical evaluation was done, and urinary steroid measurements, as well as dexamethasone suppression tests in some patients, were performed.

RESULTS

Frequently normal but intermittently increased urinary 17-hydroxycorticosteroid or cortisol excretion (or both) was found in six patients postoperatively, associated with intermittently severe hypertension, headaches, and weakness in only one patient. In a seventh patient, intermittently excessive cortisol excretion was clearly evident preoperatively.

CONCLUSION

Because corticoid excretion was variable preoperatively in three of the seven study patients, we conclude that intermittent hypercortisolism is commoner than previous evidence has shown, constitutes an extremely difficult diagnostic problem, and did not result from but failed to be cured by pituitary surgical treatment in 6 of 33 patients (18%). The findings emphasize the need for regular follow-up for several years in all patients with Cushing's syndrome who have undergone a hypophysial surgical procedure. Variable consistency of follow-up might partly explain the wide discrepancies between reports of 80 to 90% and 40 to 60% cure rates after a single hypophysial adenomectomy.

Assessment of endocrine function after transsphenoidal surgery for Cushing's disease

OBJECTIVE

We assessed the endocrine outcome after transsphenoidal surgery for Cushing's disease.

DESIGN

Five-year (mean) follow-up (range 1 month-12 years) of patients undergoing transsphenoidal surgery for Cushing's disease between 1977 and 1990; review of case notes, current clinical and biochemical assessment including 24-hour urinary free cortisol.

SETTING

Northern Ireland.

SUBJECTS

Forty-one patients (33F: 8M); mean age at diagnosis 39.1 years (9-72 years).

MAIN OUTCOME MEASURES

Measurements of early post-operative 0800 h serum cortisol and 24-hour urinary free cortisol at least 24 hours after withdrawal of oral hydrocortisone therapy. This was followed by low dose dexamethasone testing. Current 24-hour urinary free cortisol measurements. Retrospective definition of cure.

RESULTS

Twenty-seven patients were either cured or improved by surgery, 14 were considered definite failures. Of 19 patients cured, eight had unmeasurable early post-operative 0800 h serum cortisol levels while of 15 tested, 13 had complete suppression with dexamethasone and two suppressed normally but to still measurable levels (39 and 60 nmol/l respectively). Seventeen patients in total have subsequently had bilateral adrenalectomy of whom two have developed Nelson's syndrome. Seven of the 41 patients were shown to have definite cyclical cortisol secretion first diagnosed post-operatively in three patients. Hormone deficiency included TSH (5), LH/FSH (1), cortisol (1) and ADH (temporary in 7, permanent in 1). In all, seven patients had some type of permanent hormonal deficiency post-operatively.

CONCLUSIONS

Transsphenoidal surgery offers a worthwhile cure rate without the necessity of life-long endocrine therapy. Post-operative endocrine assessment must be rigorous so that early further management can be planned in the significant percentage of patients in whom cure is not achieved. Early complete suppression on low dose dexamethasone testing is very suggestive of cure but repeated and long-term monitoring of 24-hour urinary free cortisol is advisable.