| Cushing's Disease
and Cushing's Syndrome by Ray Sahelian, M.D.
Cushing's syndrome is characterized by a series of systemic complications
that increase cardiovascular risk and cause severe atherosclerotic damage
that develops in parallel with an acquired metabolic syndrome. Short-term
remission from hypercortisolism improves metabolic and vascular damages,
but long-term remission from Cushing's syndrome seems to be associated
with similar or worse metabolic and vascular damage, probably because of
persistent abdominal obesity or insulin resistance years after
normalization of cortisol secretion. Study results suggest that an
increased cardiovascular risk also may persist in patients who undergo
treatment with exogenous glucocorticoids after therapy withdrawal.
Screening studies in high-risk populations have
suggested that Cushing's syndrome is more common than previously appreciated.
Patients who have specific signs and symptoms or clinical diagnoses known to be
associated with high cortisol should be considered for screening.
Cushing disease is the most common form of Cushing
syndrome.
Cushing's Disease Diagnosis
The
measurement of late-night salivary cortisol provides the most sensitive method
for screening, and urine-free cortisol and low-dose dexamethasone suppression
testing may be used for confirmation of the diagnosis of endogenous
hypercortisolism.
Another opinion - Diagnostic tests used to screen for
Cushing's syndrome include 24-hour urine cortisol, the 1 mg dexamethasone
suppresion test, and late night salivary cortisol. A normal screening test
excludes the diagnosis of Cushing's. Patients with an abnormal screening test
should be referred to an endocrinologist for complete evaluation of the
pituitary-adrenal axis.
Cushing's Syndrome Treatment
The successful treatment of Cushing syndrome depends
on specific therapy directed against the cause of hypercortisolism. In
addition to surgical procedures, various drugs have been employed in the
management of this difficult disease. Compounds with neuromodulatory properties
have been effective in only a limited number of cases. These agents include
serotonin antagonists (cyproheptadine,
ketanserin, ritanserin), dopamine agonists (bromocriptine, cabergoline),
GABA
agonists (valproic acid [sodium valproate]), and somatostatin analogs (octreotide).
Complications of Cushing's
Disease and Cushing's Syndrome
Cushing's syndrome results from prolonged exposure to excess
glucocorticoids. Patients with Cushing's syndrome may develop multiple metabolic
problems including obesity, hyperglycemia, hypertension, depression, low bone
mass, muscle atrophy, and hypogonadism. Cutaneous manifestations of
hypercortisolism include skin atrophy, excessive bruising, purple striations,
poor wound healing, facial plethora, vellous hypertrichosis and hirsutism.
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