Abstract and Introduction
Background: Cushing syndrome (CS) is the result of extended exposure to excessive glucocorticoids from endogenous or exogenous sources. Traditionally, the most common cause of endogenous CS is a pituitary adenoma (Cushing disease). Less common causes are adrenocortical tumors and extrapituitary adrenocorticotropin-producing neoplasias.
Objectives: This review provides updated information regarding the potential for increased prevalence of CS in specific patient populations. Here the authors provide to family physicians clinical guidance for recognition of CS by presenting a case, discussing the advantages/disadvantages of the diagnostic tests, and discussing information about the treatment options.
Results: CS is expected to have an incidence of 10 to 15 people per million; however, studies of patients with diabetes, obesity, hypertension, and osteoporosis found a high prevalence of CS among these populations. The clinical manifestations of CS range from the distinctive clinical features (purple striae, facial plethora, proximal myopathy) to common conditions such as hypertension, obesity, and diabetes. Clinical practice guidelines recommend biochemical tests to screen patients for CS; however, the sensitivity and specificity of these tests vary, so a careful analysis must be performed to avoid misdiagnosis.
Conclusion: CS is challenging to diagnose. Nevertheless, with a systematic approach to testing patients and an increased awareness of the high-risk patient populations, the disease can be identified in a timely manner.
A 52-year-old, postmenopausal woman had a history of obesity (body mass index [BMI] = 32), a 4-year history of type 2 diabetes mellitus, and a 3-year history of hypertension, which were being managed with oral medications. The patient was being treated with metformin and sitagliptin for diabetes (glycosylated hemoglobin [HbA1c] = 7.8%), and her hypertension was being controlled with an angiotensin-converting enzyme inhibitor and a calcium channel blocker. In addition, she was being treated with sertraline for depression. The patient referred herself to an urgent care center for persistent foot pain without recollection of trauma. A radiograph revealed a fracture of the third metatarsal bone, which was treated by immobilization. The injury prompted her primary care physician to measure her bone mineral density. The T-score of both the lumbar spine (−2.4) and femoral neck (−2.3) indicated osteopenia. Nevertheless, testing for secondary causes of bone loss were normal (serum calcium, parathyroid hormone, and vitamin D) and the patient was treated with a bisphosphonate to prevent further bone loss.
Four months later, the patient was taken to an emergency department for an episode of acute abdominal pain, diagnosed as diverticulitis. While admitted, a computed tomography (CT) scan of the abdomen detected a low-density adrenal mass measuring 2 cm on the left side. Follow-up testing determined that urine metanephrines were normal, urinary free cortisol (UFC) was just below the upper limit of normal (47 μg/24 hours; upper limit of normal <50 μg/24 hours), and plasma adrenocorticotropic hormone (ACTH) was low (<5 pg/mL). The diagnosis of Cushing syndrome (CS) was considered and a failure to suppress cortisol (5.2 μg/dL; normal <1.8 μg/dL) following a 1-mg dose of dexamethasone (dexamethasone suppression test [DST]), and 2 mildly elevated, late-night salivary cortisol levels confirmed the diagnosis. She underwent a left laparoscopic adrenalectomy. After a 9-month period of adrenal insufficiency, her cortisol secretion normalized. The patient lost weight (BMI = 27 1 year after surgery), her hypertension improved, control of her diabetes was restored (HbA1C = 6.3%) while taking metformin only, and she did not experience any new fractures. As the initial contact for patients who demonstrate the signs of cortisol excess, family physician practitioners face the initial challenge of recognizing the signs of hypercortisolism followed by the responsibility of initiating referrals and ensuring the best possible treatment for their patients all while avoiding overtesting their patient.
J Am Board Fam Med. 2012;25(2):199-208. © 2012 American Board of Family Medicine