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Cushing's Syndrome: Screening and Diagnosis
No full textEndogenous 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 24 h 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 <50 nmol/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 24 h, 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
Pasireotide for the treatment of Cushing's disease.
No full textImportance of the field: It is important to treat patients with Cushing's disease as rapidly as possible to limit both the mortality and morbidity of the disease. Pituitary surgery remains the treatment of choice, but the rate of cure at long-term follow-up is suboptimal and recurrence rates are high. If surgery fails or relapse occurs, no treatment has proven to be fully satisfactory. Currently available medical therapies are considered a transient and palliative treatment. However, recently there has been renewed interest in medical therapy due to new insights in pathogenetic mechanisms of corticotroph pituitary tumors.
Areas covered in this review: We summarize the pharmacodynamics and possible mechanism of action of pasireotide (SOM230), a novel multireceptor-targeted somatostatin analogue. Pasireotide has a unique binding profile, with high affinity for four of the five somatostatin receptors, especially SSTR(5), the receptor most prevalent in corticotroph tumors.
What the reader will gain: The reader should gain an understanding of preclinical and clinical data supporting the potential use of pasireotide in patients with Cushing's disease.
Take home message: Preliminary data suggest that pasireotide shows promise as a tumor-targeted medical therapy in patients with Cushing's disease. If the efficacy of pasireotide is confirmed by larger studies, this compound may be a useful treatment option not only in patients with severe Cushing's disease, but also in patients with mild hypercortisolism where its efficacy might be more evident
New treatment guidelines on Cushing's disease.
No full textIt is important to treat patients with Cushing's disease as rapidly as possible to limit its long-term mortality and morbidity. Selective transphenoidal pituitary adenomectomy remains the treatment of choice but, unfortunately, the rate of cure at long-term follow-up is suboptimal and recurrences are high, even in the hands of expert neurosurgeons. Treatment options for persistent or relapsed disease include repeat trasphenoidal pituitary surgery, radiotherapy or bilateral adrenalectomy. Medical treatment, a second-line treatment option, may have either a primary or adjunctive role if the patient cannot safely undergo surgery, if surgery fails, or if the tumor recurs. Cabergoline and pasireotide (SOM230), two pituitary tumor-directed drugs, are the most exciting news in the human pharmacological approach. However, the use of these drugs in clinical practice and their real impact in the management of patients is yet to be determined. The treatment of patients with Cushing's disease is complex and requires a multidisciplinary and individualized approach to patient management using cost-benefit analyses
Approach to the patient with possible Cushing's syndrome
Full text linkClinical decision making for patients with suspect hypercortisolism involves a complex diagnostic assessment. Cushing's syndrome remains one of the most challenging endocrine pathologies. Most clinical features overlap with those of common diseases found in the general population, and some patients have an atypical clinical presentation with only isolated symptoms. Recently, several studies have suggested that the prevalence of Cushing's syndrome is higher than previously thought. Therefore, efficient screening tests are needed to identify the few uncovered patients also among unselected high-risk ambulatory patients with disorders potentially related to cortisol excess. The recommended diagnostic tests are 24-h urinary free cortisol, 1-mg overnight dexamethasone suppression test, and late-night salivary cortisol. Once the diagnosis of Cushing's syndrome is established, the next step is the measurement of plasma ACTH. Then, dynamic test and appropriate imaging procedures are the most useful noninvasive investigations for the differential diagnosis. Patients with Cushing's disease are generally responsive to the CRH test and to high-dose glucocorticoid feedback. Bilateral inferior petrosal sinus sampling is considered the gold standard for establishing the origin of ACTH secretion, and it is recommended in patients with ACTH-dependent Cushing's syndrome whose clinical, biochemical, or radiological studies are discordant or equivocal. The present clinical case shows that even if rare, the ectopic ACTH secretion should be considered also in those cases where the pretest probability is low. The management of Cushing's syndrome depends on the exact knowledge of its various causes, paying attention to the many potential diagnostic pitfalls. The choice of test, the modality of specimen collection (blood, urine, and saliva), the quality of measurement (assay methodology and standardization), and close dialogue among endocrinologists, chemical pathologists, and neuroradiologists are key factors for optimal care of patients
Clinical use of pasireotide for Cushing's disease in adults.
Full text linkAbstract
Cushing's disease: Excessive corticotroph hormone levels sustained by an adrenocorticotropic hormone-secreting pituitary adenoma lead to a severe clinical condition caused by excess cortisol secretion, called Cushing's disease (CD). Neurosurgery and radiotherapy are used to treat the pituitary adenoma directly, but new medical treatments targeting the corticotroph cells have recently become available.
Pasireotide: This is a novel multireceptor ligand somatostatin (SST) analog with a high binding affinity for SST receptor 5, the predominant receptor in human corticotroph adenomas that is not downregulated by high cortisol levels (as SST receptor 2 is). Pasireotide has been recently approved by the European Medical Agency and the US Food and Drug Administration for treating adults with CD with recurrent hypercortisolism after surgery, or for whom surgery is not an option. A dose of 600-1,200 mu g twice a day can normalize urinary free cortisol levels after 3 months of treatment in up to 28% of patients, reducing their blood pressure and improving their weight, lipid profile, and quality of life. Combining pasireotide with cabergoline to achieve a greater hormone response can normalize cortisol secretion in 50% of patients, and adding ketoconazole induces biochemical control in most patients with CD.
Safety and hyperglycemia: The adverse effects of pasireotide are similar to those of other SST analogs, including diarrhea, nausea, and biliary sludge or gallstones. Hyperglycemia is common during pasireotide treatment, which affects the secretion of pancreatic insulin and intestinal glucagon-like peptide 1. Self-monitoring is essential to achieve good metabolic control, and endocrinologists should first administer metformin if insulin resistance is evident and then add dipeptidyl peptidase 4 inhibitors/glucagon-like peptide 1 receptor agonists or insulin.
Conclusion: In recent years, medical treatment with pasireotide has been proposed as monotherapy for adults with CD characterized by mild to moderate hypercortisolemia, as well as in combination with other available therapies. It is generally well-tolerated, but endocrinologists need to monitor glucose levels to ensure prompt treatment
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