|
·
Free circulating glucocorticoids.
Causes
Bilateral
hyperplasia as 2º effect.
Pituitary-dependent (Cushing’s
disease):
65%
From ACTH-secreting tumor in pituitary.
Ectopic ACTH-secreting tumors:
10%
Paramalignant, from ACTH-secreting SCC lung.
Non-ACTH-dependent causes:
|
Adrenocortical
adenoma / carcinoma.
Iatrogenic (Glucocorticoid
administration)
|
 |
Cushingoid appearance |
Adrenal cortex atrophy.
Clinical Features:
Symptoms
|
Cause
|
|
Hirsutism
|
Adrenal androgen secretion.
|
|
Muscle
weakness
|
Proximal
myopathy (protein breakdown) & Hypokalemia
|
|
Back
pain
|
Osteoporosis
& proximal myopathy
|
|
Oligomenorrhea,
amenorrhea, ¯libido,
impotence.
|
Gonadal
Dysfunction.
|
|
Depression
|
|
|
Signs
|
Cause
|
|
Central
obesity “lemon on match-stick”
|
|
|
Moon
face
|
Round
plethoric appearance
|
|
Plethoric
appearance
|
Thinning
of skin.
|
|
Thin
skin, bruising, Purplish striae
|
Collagen
breakdown.
|
|
Hypertension
|
Plasma volume & Na+
retention
|
|
Skin
infections
|
¯ Immunity
|
|
Buffalo
hump
|
Fat
accumulation at lower part of neck.
|
*
Plethora = generalized edema.
N.B.
Patient is not overweight; rather, fat is redistributed so
that it looks like central obesity.
v
Features of
Cushing’s syndrome of ectopic ACTH secretion:
q
Pigmentation.
q
Hypokalemic
alkalosis
(due to mineralocorticoid activity of cortisol).
q
Impaired
glucose tolerance
(IGT).
N.B. Old photographs may be
useful to see development of Cushing’s syndrome
Diagnosis:
·
Confirmed
when cortisol is always ,
not suppressed by exogenous glucocorticoid.
1. P-cortisol
levels:
Change in circadian rhythm:
midnight cortisol levels.
2. 24h
U-free cortisol measurements .
3. 48h
low-dose dexamethasone test:
Fail to show suppression of P- & U-cortisol levels.
Treatment
:
1. Radiotherapy.
2. Trans-sphenoidal
selective adenomectomy (for Cushing’s disease).
3. Long-term
medical treatment.
4. Bilateral
adrenalectomy
(last resort).
N.B.
§
Cushing’s
disease
P-ACTH à in ACTH-dependent disease.
§
Ectopic
ACTH syndrome à
P-ACTH.
§
Nelson’s
syndrome:
q
P-ACTH à severe pigmentation.
q
With
enlarging pituitary tumor.
q
Develops
in patients with Cushing’s disease (bilateral pituitary-dependent
adrenal hyperplasia) treated by bilateral adrenalectomy.
q
Rare
now!
§
Incidentalomas: incidental adrenal tumors on imaging.
written
by:
Khalid Bin Yaroof. FMHS, UAE University.
| 
