ADRENAL GLAND

Introduction to the adrenal gland:
The adrenal glands are triangular shaped orange colored endocrine glands which are located on the top of both kidneys.
Medulla (the center of the gland) - epinephrine and norepinephrine
Cortex which surrounds the medulla - (cortisone and aldosterone)
Zona glomerulosa produces aldosterone by the activation of rennin-angiotensin-aldosterone system.
Zona fasciculata & Zona reticularis synthesize: 
Glucocorticoids- deoxycortisol, cortisol
Sex hormones- estrogen, androgen
Weak mineralocorticoids- deoxycorticosterone, corticosterone

Cushing’s Syndrome or hypercortisolism 

It occurs when a person's tissues are exposed to an excess of the hormone cortisol.
Causes:
The most common cause of cushing syndrome is long term therapy with glucocorticoids.
Pituitary’s Cushing’s or Cushing’s disease - A noncancerous tumor of the pituitary gland that produces increased amounts of the hormone adrenocorticotropin (ACTH). This, in turn, prompts the adrenal glands to produce too much cortisol.
Adrenal Cushing’s - Certain types of cancerous tumors in other parts of the body can produce ACTH, causing the adrenal glands to produce extra cortisol. eg Small cell ca of lung.
Ectopic Cushing’s - Ectopic Cushing's syndrome is caused by tumors that secrete adrenocorticotropic hormone (ACTH).

Clinical features
Weight gain- moon face (round, red, and full)
buffalo hump" -- collection of fat between the shoulders
central obesity -- protruding abdomen and thin extremities
Glucose intolerance due to increased gluconeogenesis.
Hirsutism due to increased 17-KS.
Purple abdominal striae.
Increased Thirst and increased urination.
Acne or superficial skin infections.
Mental changes
Impotence or cessation of menses.
Osteoporosis
Diastolic hypertension due to increased synthesis of weak mineralocorticoids.

Lab
Best screening test is 24 hour urinary free cortisol.
A urine collection for17-hydroxycorticoids (contains cortisol & 11- deoxycortisol).
A urine collection for 17-ketosteroids (17-KS) (contains weak androgens like Dehydroandrosterone or DHEA or androstenedione)
Serial serum cortisol levels -- do not show diurnal variations
Low dose dexamethasone test-urine is collected at 24-hour intervals over 3 days for measurement of cortisol. On day 2, a low dose (0.5 mg) of dexamethasone is given by mouth every 6 hours for 48 hours. Cortisol is not suppressed. It is used only for screening and is not a confirmatory test.
High-dose dexamethasone test is a confirmatory test in which urine is collected at 24-hour intervals over 3 days for measurement of cortisol. On day 2, a high dose (2 mg) of dexamethasone is given by mouth every 6 hours for 48 hours. Cortisol is suppressed in Pituitary cushing’s or cushing’s disease but there is no change in other types of Cushing’s.