ADRENAL DISORDERS Flashcards
Which 3 kinds of steroid hormones does the adrenal cortex produce, with examples?
- Sex steroids (e.g. androgens)
- Mineralocorticoids (e.g. aldosterone)
- Glucocorticoids (e.g. cortisol)
Name 2 functions of mineralocorticoids
- Mineral homeostasis (Increase Na+ and decrease K+)
- Maintain blood volume
What is the main function of glucocorticoids such as cortisol?
Helps body during exposure to stress
Name 3 catabolic effects of glucocorticoids such as cortisol
- Inhibits protein synthesis
- Lipolysis
- Promotes bone resorption
Name 3 anabolic effects of glucocorticoids (e.g. cortisol)
- Stimulates gluconeogenesis (conversion of proteins and fats into glucose)
- Promotes liver glycogen synthesis and storage
- Increases central fat deposition
Why are glucocorticoids used therapeutically as anti-inflammatory and immunosuppressive drugs?
- Decreases vascular permeability
- Decreases WBCs and WBC activity
- Inhibits cell mediated immunity
What are 3 adverse effects of glucocorticoids?
- Increases risk of infection
- Decreased wound healing
- Sodium + water retention
What type of hormones does the adrenal medulla secrete?
Catecholamines (e.g. epinephrine and norepinephrine)
Name 5 steps of adrenal gland regulation
- Stimulus (e.g. stress)
- Hypothalamus secretes CRH (corticotropin releasing hormone)
- CRH stimulates anterior pituitary to release ACTH (adrenocorticotropic hormone)
- ACTH stimulates adrenal cortex to secrete cortisol
- Cortisol inhibits hypothalamus and anterior pituitary
What are 2 terms for a condition of excess cortisol?
Hypercortisolism or Cushing syndrome
What is the most common cause of Cushing syndrome?
Adverse effect of therapeutic glucocorticoids
What is the cause behind primary hypercortisolism?
Adrenal hyperplasia or adrenal tumours that hypersecrete ACTH
What is the cause behind secondary hypercortisolism, also called Cushing disease?
Pituitary adenoma that hypersecretes ACTH
Besides adrenal hyperplasia, adrenal tumours, and a pituitary adenoma, what is another possible cause for excess ACTH leading to hypercortisolism?
Ectopic production of ACTH, e.g. small cell lung cancer
Why do symptoms of hypercortisolism include muscle weakness and osteoporosis?
Cortisol inhibits protein synthesis causing muscle atrophy
Cortisol promotes bone resorption
What are 2 metabolic effects of hypercortisolism?
- Central fat deposition with thin limbs, leading to “moon face” or “buffalo hump”
- Hyperglycemia & insulin resistance
Why do symptoms of hypercortisolism including hypertension and hypokalemia?
Cortisol has a mineralocorticoid effect:
Promotes sodium and water retention
Promotes excretion of potassium in urine
What symptoms may some women experience with hypercortisolism?
Androgen excess, leading to development of male secondary sex characteristics
Why are purple striae (stretch marks) a symptom of hypercortisolism?
Decreased collagen (protein) formation
What kind of lab test would help distinguish between a primary or secondary cause for hypercortisolism?
Plasma ACTH
(in primary hypercortisolism the ACTH level will be normal, while in secondary it will be high)
What kind of test may be done to distinguish between Cushing disease and ectopic ACTH production, and why?
Dexamethasone suppression test
Dexamethasone is a cortisol analog:
If cortisol suppressed, means ACTH is being secreted by pituitary adenoma (affected by negative feedback)
If cortisol not suppressed, means ACTH is being produced ectopically (not affected by negative feedback)
Name the 6 steps of the RAA pathway that results in aldosterone secretion by the adrenal cortex
- Drop in blood pressure/volume
- Kidneys release renin
- Renin converts angiotensinogen (made by liver) into angiotensin I
- Lungs release ACE independently
- ACE converts angiotensin I into angiotensin II
- Angiotensin II stimulates the adrenal cortex to release aldosterone
What are the target tissues of aldosterone?
Distal tubules and collecting ducts in nephrons of kidneys
What are 2 purposes of the sex steroids produced by the adrenal cortex?
- Growth in children
- Maintenance of pubic/axillary hair and libido in females
What is the name of the cells of the adrenal medulla that produce catecholamines in response to sympathetic stimuli?
Chromaffin cells (pheochromocytes)
What is the term for a chromaffin cell tumour?
Pheochromocytoma
Which 3 symptoms form the “classic triad” associated with pheochromocytoma?
- Headache
- Tachycardia
- Sweating
