Cushing's syndrome

Cushing's syndrome
Name	Cushing's syndrome
Synonyms	Hypercortisolism
Field	Endocrinology

Cushing's syndrome is an endocrine disorder resulting from chronic exposure to elevated glucocorticoid levels. It presents with characteristic metabolic, dermatologic, musculoskeletal, and neuropsychiatric manifestations and requires integration of clinical findings with biochemical testing and imaging for diagnosis. Management often involves surgery, medical therapies, and multidisciplinary care from specialists across endocrinology, neurosurgery, and oncology.

Signs and symptoms

Patients commonly develop central adiposity, moon facies, and dorsocervical fat pad, with progressive weight gain and truncal obesity observed in many reports involving cohorts from Mayo Clinic, Johns Hopkins Hospital, Massachusetts General Hospital, Cleveland Clinic, and Karolinska Institutet. Cutaneous features include purple striae, easy bruising, acne, and hirsutism noted in case series from Royal Free Hospital, Guy's and St Thomas' NHS Foundation Trust, and Addenbrooke's Hospital. Musculoskeletal complaints such as proximal muscle weakness, osteoporosis, and vertebral fractures are described in registries at Hospital Clínic de Barcelona, Charité – Universitätsmedizin Berlin, and Hospital for Sick Children. Neuropsychiatric manifestations—depression, cognitive impairment, anxiety, and sleep disturbance—appear in cohorts from University of Oxford, King's College London, and University of California, San Francisco. Metabolic derangements like hyperglycemia, dyslipidemia, and hypertension are frequently documented in studies from Stanford University Medical Center, University of Pennsylvania Health System, and Imperial College London. Reproductive effects such as amenorrhea and decreased libido have been reported by groups at Mount Sinai Hospital (New York), Royal Melbourne Hospital, and Toronto General Hospital.

Pathophysiology

Excess circulating cortisol alters carbohydrate, fat, and protein metabolism through actions on glucocorticoid receptors, with downstream genomic and non-genomic effects characterized in research from National Institutes of Health, European Molecular Biology Laboratory, and Wellcome Trust Sanger Institute. Chronic cortisol exposure promotes insulin resistance—documented in studies at Harvard Medical School and Yale School of Medicine—and redistributes adipose tissue by modulating adipokines in experiments from Institut Pasteur and Max Planck Society. Bone resorption and muscle catabolism involve signaling pathways investigated at Fred Hutchinson Cancer Center and Dana-Farber Cancer Institute. Hypothalamic–pituitary–adrenal (HPA) axis dysregulation with loss of negative feedback is central in pituitary-driven cases studied at University of Cambridge and Uppsala University, while ectopic ACTH production and adrenal autonomy are mechanisms elucidated by teams at Shanghai Jiao Tong University School of Medicine and Seoul National University Hospital.

Causes and classification

Etiologies are classified by source: ACTH-dependent and ACTH-independent disease. ACTH-secreting pituitary adenomas (often termed by clinicians but not linked here) account for a substantial portion and are resected by surgeons from Johns Hopkins Hospital and University of California, Los Angeles. Ectopic ACTH secretion from neuroendocrine tumors has been reported at Moffitt Cancer Center, Memorial Sloan Kettering Cancer Center, and MD Anderson Cancer Center. Adrenal adenomas, carcinomas, and bilateral adrenal hyperplasia produce ACTH-independent hypercortisolism; pathology series from Mayo Clinic and UCSF Medical Center describe these subtypes. Exogenous corticosteroid exposure—prescribed for autoimmune disease, transplantation, or inflammatory disorders—is a major iatrogenic cause documented in prescribing audits from NHS England, Veterans Health Administration, and World Health Organization surveillance reports.

Diagnosis

Diagnosis integrates screening tests (overnight dexamethasone suppression, 24-hour urinary free cortisol, late-night salivary cortisol) and confirmatory assays validated in laboratories at Centers for Disease Control and Prevention, Quest Diagnostics, and Laboratory Corporation of America. Plasma ACTH measurement distinguishes ACTH-dependent from ACTH-independent disease in protocols adopted by European Society of Endocrinology and Endocrine Society. Localization employs pituitary MRI interpreted at Mayo Clinic and nuclear medicine studies such as octreotide scintigraphy and PET performed at Johns Hopkins Hospital and Royal Marsden Hospital. Inferior petrosal sinus sampling is a specialized procedure executed at tertiary centers including UCL Hospitals and Hospital de la Santa Creu i Sant Pau when noninvasive tests are inconclusive. Differential diagnosis involves conditions reported by clinics at Cleveland Clinic and John Radcliffe Hospital.

Treatment

First-line therapy depends on etiology: transsphenoidal surgery by neurosurgeons at University of Pittsburgh Medical Center and Cleveland Clinic is common for pituitary sources, while adrenalectomy is performed by endocrine surgeons from Massachusetts General Hospital and Guy's and St Thomas' NHS Foundation Trust for adrenal tumors. Medical therapies (steroidogenesis inhibitors, glucocorticoid receptor antagonists) developed in trials at Novartis, Pfizer, and AstraZeneca are used when surgery is contraindicated or as bridging therapy; medications include agents evaluated in studies at European Medicines Agency and U.S. Food and Drug Administration trials. Radiation therapy and stereotactic radiosurgery at centers such as Karolinska University Hospital and The Royal Marsden NHS Foundation Trust are options for residual or recurrent pituitary disease. Long-term management addresses comorbid diabetes, hypertension, and osteoporosis with guidance from American Diabetes Association, American Heart Association, and National Osteoporosis Foundation.

Epidemiology

Population-based estimates from registries in Scotland, Sweden, Denmark, United States, and Japan show an incidence of several cases per million per year and a higher prevalence among females, particularly in reproductive age groups, with variable reporting across datasets from European Union and United Nations health statistics. Iatrogenic hypercortisolism from prescribed corticosteroids substantially increases the population-level burden documented in pharmacoepidemiology surveys from World Health Organization and national health services.

History and society

Descriptions of hypercortisolism trace to clinical observations in hospitals such as Guy's Hospital and academic centers including University of Edinburgh and Columbia University; the eponym commemorates work by clinicians and anatomists associated with institutions like Peter Bent Brigham Hospital and Boston City Hospital who characterized the syndrome in the early 20th century. Advances in biochemical assays and imaging from National Institutes of Health and Imperial College London transformed diagnosis and management, while patient advocacy organizations including groups affiliated with European Society of Endocrinology and national endocrine societies have influenced awareness, guideline development, and research funding. High-profile clinical cases reported in media outlets tied to BBC News, The New York Times, and The Guardian have raised public attention to the condition.

Category:Endocrinology