4. Introduction
Constellation of clinical features that result from
chronic exposure to excess glucocorticoids
(cortisol) of any etiology
Cushing's disease---->Cushing's syndrome
caused by a pituitary corticotrope adenoma
5. Etiology
ACTH-dependent Cushing syndrome
Hypothalamic lesions--- increased CRH
Pituitary lesions (75%)– Microadenoma,
macroadenoma
Ectopic production of ACTH(10%)---islet cell
carcinoma of the pancreas, neuroblastoma or
ganglioneuroblastoma, hemangiopericytoma,
Wilms tumor, and thymic carcinoid
8. Bruising & Abdominal striae
Loss of subcutaneous
connective tissue due to
catabolic effects of
glucocorticoids exposes
underlying vessels prone
to rupture
Catabolic effect on
Fibroblasts
Mechanism is similar with
abdominal striae
9. Cushingoid Habitus:
Glucocorticoids
decrease AMP kinase
enzyme in Visceral
adipose tissues
(increased lipogenesis,
lipid stores & lipolysis)
In hypothalamus,
glucocorticoids increase
AMPK which stimulates
appetite
The cause for characteristic
preferential deposition in
face (moon facies and
10. Hirsutism:
No clear
mechanism
Excess ACTH
stimulates zona
glomerulosa, zona
fasciculata, zona
reticularis
producing cortisol,
androgens and
probably hirsutism
12. Polyuria:
Excess glucocorticoids block osmosis
dependent ADH secretion from hypothalamus
Directly also enhances free water clearence
13. Proximal myopathy:
Glucocorticoids cause breakdown of muscle
proteins (decreased sarcolemmal activity and
increased myosin degeneration)
Hypokalemia associated causes
hyperpolarization causing it more difficult for
the cells to fire
ACTH directly blocks muscle transmission by
decreasing endplate potential
Patient tend to have low levels of physical
acticity
14. System Signs and symptoms
Body fat Weight gain, central obesity, rounded face,
fat pad on back of neck ("buffalo hump")
Skin Facial plethora, thin and brittle skin, easy
bruising, broad and purple stretch marks,
acne, hirsutism
Bone Osteopenia, osteoporosis (vertebral
fractures), decreased linear growth in children
Muscle Weakness, proximal myopathy (prominent
atrophy of gluteal and upper leg muscles)
Cardiovascular
system
Hypertension, hypokalemia, edema,
atherosclerosis
15. System Signs and symptoms
Metabolism Glucose intolerance/diabetes, dyslipidemia
Reproductive
system
Decreased libido, in women amenorrhea (due
to cortisol-mediated inhibition of gonadotropin
release)
CNS Irritability, emotional lability, depression,
sometimes cognitive defects, in severe cases,
paranoid psychosis
Blood and
immune
system
Increased susceptibility to infections, increased
white blood cell count, eosinopenia,
hypercoagulation with increased risk of deep
vein thrombosis and pulmonary embolism
16. Laboratory diagnosis
Circadian rhythm is lost; midnight cortisol
levels >4.4 mcg/dL--- strongly suggest the
diagnosis
Elevated nighttime salivary cortisol levels
raise suspicion for Cushing syndrome.
A single-dose dexamethasone suppression
test
A dose of 25-30 mcg/kg (maximum of 2 mg) given
at 11 pm ------> results in a plasma cortisol level
17. Level of ACTH
CRH and High dose dexamethasone
suppression test
Inferior petrosal sinus sampling---for ACTH
level
CT/MRI
18.
19.
20. Management
Transsphenoidal pituitary microsurgery
Treatment of choice in pituitary Cushing disease in
children
Cyproheptadine, a centrally acting serotonin
antagonist that blocks ACTHrelease, has been
used to treat Cushing disease in adults
If a pituitary adenoma does not respond to
treatment or if ACTH is secreted by an ectopic
metastatic tumor, the adrenal glands may need to
be removed
21. Pituitary irradiation
Considered as primary therapy for children under age 18.
Pituitary irradiation is one of the next treatment options in
Whom fertility is an important concern
Whom a tumor is not found
Who are not cured by transsphenoidal resection of a tumor
22. Management of patients undergoing
adrenalectomy
Adequate preoperative and postoperative
replacement therapy with a corticosteroid
Tumors that produce corticosteroids----> atrophy
of the normal adrenal tissue, and replacement with
cortisol (10 mg/m2/24 hr in 3 divided doses after
the immediate postoperative period) is required
until there is recovery of the hypothalamic-pituitary-
adrenal axis
Postoperative complicatios---sepsis, pancreatitis,
23. After adrenalectomy
May lead to increased ACTH secretion by an unresected
pituitary adenoma, evidenced mainly by marked
hyperpigmentation: Nelson Syndrome.
24. Reference
Kliegman et al, Nelson Textbook of Pediatrics,
19th
edition
Ghai, Essential Pediatrics, 8th
edition
Harrison’s principle of Internal Medicine 20th
edition
Davidson’s Principles & Practices of Medicine
Circulating cortisol concentrations drop under the rhythm-adjusted mean (MESOR) in the early evening hours, with nadir levels around midnight and a rise in the early morning hours; peak levels are observed 8:30 A.M. (acrophase)