Pseudo-Cushing's syndrome
Encyclopedia
Pseudo-Cushing's syndrome is a medical condition in which patients display the signs
, symptom
s, and abnormal hormone
levels seen in Cushing's syndrome
. However, pseudo-Cushing's syndrome is not caused by a problem with the hypothalamic-pituitary-adrenal axis
as Cushing's is; it is an idiopathic
condition.
Medical sign
A medical sign is an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination of a patient....
, symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s, and abnormal hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
levels seen in Cushing's syndrome
Cushing's syndrome
Cushing's syndrome is a hormone disorder caused by high levels of cortisol in the blood. This can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone or CRH...
. However, pseudo-Cushing's syndrome is not caused by a problem with the hypothalamic-pituitary-adrenal axis
Hypothalamic-pituitary-adrenal axis
The hypothalamic-pituitary-adrenal axis , also known as thelimbic-hypothalamic-pituitary-adrenal axis and, occasionally, as the hypothalamic-pituitary-adrenal-gonadotropic axis, is a complex set of direct influences and feedback interactions among the hypothalamus, the pituitary gland ,...
as Cushing's is; it is an idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
condition.
Investigations
- Levels of cortisolCortisolCortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...
and ACTH both elevated - 24-hour urinary cortisol levels elevated
- Dexamethasone suppression testDexamethasone suppression testThe dexamethasone suppression test is designed to diagnose and differentiate among the various types of Cushing's syndrome and other hypercortisol states.It has also been used in the research of depression.-Physiology:...
fails to suppress serum cortisol - Loss of diurnal variation in cortisol levels (seen only in true Cushing's Syndrome)
- High mean corpuscular volumeMean corpuscular volumeThe mean corpuscular volume, or "mean cell volume" , is a measure of the average red blood cell size that is reported as part of a standard complete blood count....
and gamma-glutamyl transferase may be clues to alcoholismAlcoholismAlcoholism is a broad term for problems with alcohol, and is generally used to mean compulsive and uncontrolled consumption of alcoholic beverages, usually to the detriment of the drinker's health, personal relationships, and social standing... - Polycystic Ovarian Syndrome should be ruled out; PCOS has similar symptoms
Differential diagnosis
- Differentiation from Cushing's is difficult, but several tools exist to aid in the diagnosis
- Alternative causes of Cushing's should be excluded with imaging of lungLungThe lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s, adrenal glandAdrenal glandIn mammals, the adrenal glands are endocrine glands that sit atop the kidneys; in humans, the right suprarenal gland is triangular shaped, while the left suprarenal gland is semilunar shaped...
s, and pituitary glandPituitary glandIn vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...
; these often appear normal in Cushing's - In the alcoholic patient with pseudo-Cushing's, admission to hospital (and avoidance of alcohol) will result in normal midnight cortisol levels within five days, excluding Cushing's
- Another cause for Cushing's syndrome is the extemely rare form of cancer (Adrenal Cortisol Carcinoma), when a benign lesion on the adrenal gland (which would cause Cushing's) becomes malignant and starts producing its own cortisol. This produces Cushing's-like symptoms and is fatal. Life expectancy depends on early detection. Ruling out ACC is done with a CT scan of the abdomen, identifying the size and location of adrenal tumors and lesions.
Prognosis
- Blood results and symptoms normalise rapidly on cessation of drinking or remission of depression