Endocrinology :Adrenal Gland Flashcards
Regulatory control of adrenal cortical hormones
HAP AXIS
glucocorticoids , adrenal androgens
RENIN ANGIOTNSIN ALDOSTERONE SYSTEM
Mineralocorticoids
Low dose decamethasone suppresses
Normal person only
High dose dexamethasone suppresses
Pituitary ACTH secreting tumor not ectopic ACTH production
Glucococorticoids act at nuclear= cytoplasmic receptor
Nuclear
Cause of anti inflammatory action of glucocorticoids
Repression of proimflammatory genes
Cortisol is inactivated to cortisone by
An enzyme that is found predominantly in kidney
Significance:
Cortisol and aldosterone bind the mineralocorticoid receptor (MR) with equal affinity; however, cortisol circulates in the bloodstream at about a thousandfold higher concentration. Thus, only rapid inactivation of cortisol to cortisone by 11β-HSD2 prevents MR activation by excess cortisol, thereby acting as a tissue-specific modulator of the MR pathway.
Defect in this enzyme can be a cause apparent mineralocorticoid excess
Cortisol is inactivated to cortisone by
An enzyme that is found predominantly in kidney
Significance:
Cortisol and aldosterone bind the mineralocorticoid receptor (MR) with equal affinity; however, cortisol circulates in the bloodstream at about a thousandfold higher concentration. Thus, only rapid inactivation of cortisol to cortisone by 11β-HSD2 prevents MR activation by excess cortisol, thereby acting as a tissue-specific modulator of the MR pathway.
Defect in this enzyme can be a cause apparent mineralocorticoid excess
Cushings ds
Pituitary corticotrope adenoma
MCC of cushing syndrome
Exogenous glucocorticoids
Causes of cushing syndrome
ACTH DEPENDANT
Cushing’s disease / ACTH-producing pituitary adenoma)
Ectopic ACTH syndrome (due to ACTH secretion by bronchial or pancreatic carcinoid tumors, small-cell lung cancer, medullary thyroid carcinoma, pheochromocytoma and others
ACTH INDEPENDANT
Adrenocortical adenoma
Adrenocortical carcinoma
Signs and symptoms of cushings ds
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 with difficulty climbing stairs or getting up from a chair)
CVS Hypertension hypokalemia edema Atherosclerosis
METABOLIC
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 SYATEM
Increased susceptibility to infections increased white blood cell count eosinopenia
hypercoagulation with increased risk of deep vein thrombosis and pulmonary embolism
Effect of glucocorticoids on carbohydrates, fat,protein
Gluconeogenesis
Lipolysis
Protein catabolism
Why does glucocoticoods lead to htn?
excess glucocorticoid secretion overcomes the ability of 11β-HSD2 to rapidly inactivate cortisol to cortisone in the kidney, thereby exerting mineralocorticoid actions, manifest as diastolic hypertension, hypokalemia, and edema.
Hyperpigmentation is seen in which type of cushings ds
Ectopic ACTH syndrome
Occures over knuckles, scar,skin area exposed to friction
Effect of OCP on cortisol level
Increase cortisol binding protein CBP
So inc in total cortisol but not free
Can give false positive result during cushing syn screening(failure of dexamethasone suppression , but 24 hr urinary cortisol tell about FREE cortisol so no effect on this test)
