Concept and Etiology:
Cushing syndrome is an endocrine disorder in which the pituitary gland
produces too much adrenocorticotropic hormone (ACTH). This over
production is due to a benign tumor called an adenoma which is
located on the pituitary gland that causes the pituitary gland to
malfunction and create the excess ACTH. ACTH stimulates the
production of cortisol in the adrenal glands, so when there are excess
levels of ACTH, there is excess levels of cortisol. Having Cushing
syndrome deviates from the definition of health, because your body is
no longer maintaining homeostasis and keeping hormones regulated.
Classification: a
Cushing syndrome is classified by being either ACTH dependent or
ACTH independent, and then sub categorized under one of the two
major categories:
ACTH dependent:
• Cushing's disease
• Ectopic ACTH syndrome
• Ectopic corticotropin-releasing hormone syndrome
ACTH independent:
• Iatrogenic
• Adrenal adenoma
• Micronodular hyperplasia
• Macronodular hyperplasia
(Kirk, Hash, Katner, Jones, 2000)
Clinical Manifestations:
SIGNS:
• Weight gain and fatty tissue deposits, particularly around the
midsection and upper back, in the face (moon face), and between
the shoulders (buffalo hump)
• Pink or purple stretch marks (striae) on the skin of the abdomen,
thighs, breasts, and arms
• Thinning, fragile skin that bruises easily
• Slow healing of cuts, insect bites and infections
• Acne
• Thicker or more visible body and facial hair (women)
• Skin darkening
• Bone loss, leading to fractures over time
• In children, impaired growth
SYMPTOMS:
• Severe fatigue
• Muscle weakness
• Depression, anxiety, and irritability
• Loss of emotional control
• Cognitive difficulties
• New or worsened high blood pressure
• Headache
• Loss of sexual interests
•
Diagnostic Tests:
• Physical exam looking for stretch marks, bruises, or hump
• 24-hour urinary free cortisol test: For this test, you’ll be asked to
collect your urine over a 24-hour period. The levels of cortisol will
then be tested.
• Salivary cortisol measurement: In people without Cushing’s
syndrome, cortisol levels drop in the evening. This test measures
the level of cortisol in a saliva sample that’s been collected late at
night to see if cortisol levels are too high.
• Low-dose dexamethasone suppression test: For this test, you’ll
be given a dose of dexamethasone late in the evening. Your
blood will be tested for cortisol levels in the morning. Normally,
dexamethasone causes cortisol levels to drop. If you have
Cushing’s syndrome, this won’t occur.
After you receive the diagnosis of Cushing’s syndrome, your healthcare
provider must still determine the cause of the excess cortisol
production. Tests to help determine the cause may include:
• Blood adrenocorticotropin hormone (ACTH) test: Levels of ACTH
in the blood are measured. Low levels of ADTH and high levels of
cortisol could indicate the presence of a tumor on the adrenal
glands.
• Corticotropin-releasing hormone (CRH) stimulation test: In this
test, a shot of CRH is given. This will raise levels of ACTH and
cortisol in people with pituitary tumors.
• High-dose dexamethasone suppression test: This is the same as
the low-dose test, except that a higher dose of dexamethasone is
used. If cortisol levels drop, you may have a pituitary tumor. If
they, don’t you may have an ectopic tumor.
• Petrosal sinus sampling: Blood is drawn from a vein near the
pituitary and from a vein far away from the pituitary. A shot of
CRH is given. High levels of ACTH in the blood near the pituitary
can indicate a pituitary tumor. Similar levels from both samples
indicate an ectopic tumor.
• Imaging studies: These can include things like CT and MRI
scans. They’re used to visualize the adrenal and pituitary glands
to look for tumors.
(Kahn & Biggers, 2020).
References:
Kahn, A., & Biggers, A. (2020, August 28). Everything you need to
know about Cushing's syndrome. Healthline. Retrieved November 14,
2021, from https://www.healthline.com/health/cushings-syndrome.
Kirk, L., Hash, R., Katner, H., & Jones, T. (2000). Cushing's
Disease: Clinical Manifestations and Diagnostic Evaluation. American
Family Physician, 1119–1127. Retrieved November 14, 2021, from
https://www.aafp.org/afp/2000/0901/p1119.html.
