Adrenal Cortex Disorders

Question 1

Adrenal cortex steroid hormones

Answer 1

From cholesterol
- mineralocorticoids (Na2+ and water in, K+ out)
- glucocorticoids
- sex steroids
Act on intracellular receptors (different to peptide hormones)
Enter nucleus and alter DNA transcription

Question 2

Adrenal cortex layers

Answer 2

Outer layer is the capsule 
Cortex 
- glomerulosa - secretes aldosterone (salt) 
- fasciculata - secretes cortisol (sugar)
Reticularis 
- secretes androgens (sex) 
Medulla 
- secretes catecholamines

Question 3

Mineralocorticoids

Answer 3

Sodium and water in, potassium out
DEFICIENCY 
- low Na2+ 
- dehydration 
- high potassium 
EXCESS
- high sodium 
- hypertension 
- low potassium

Question 4

Glucocorticoids

Answer 4

Increases glucose production, the breakdown of protein and the redistribution of fat 
DEFICIENCY 
- low glucose
- weight loss, underweight 
- hypotension 
- nausea 
EXCESS 
- high glucose - diabetes 
- weight gain, increased appetite 
- hypertension 
- CUSHINGOID

Question 5

The HPA axis (hypothalamus, pituitary and adrenals)

Answer 5

ACTH is secreted as it precursor - POMC
POMC is broken down to ACTH and MSH (causes pigmentation and darkening of skin e.g. dark Palmer lines in Addison’s)
ACTH stimulates the adrenal glands to produce steroid hormones
- increases ACTH secretion can lead to increased cortisol secretion (ACTH dependent Cushing’s) - could be due to pituitary or ectopic (tumour) ACTH secretion
(ACTH independent Cushing’s) - cortisol secreting adrenal tumour

Question 6

Cortisol levels

Answer 6

Max in the morning (low then = Addison’s)
Min at midnight (high then = Cushing’s)
Timing of tests is important

Question 7

Addison’s Disease

Answer 7

RARE endocrine disorder - autoimmune destruction of adrenal cortex
Female predominance
- destruction of entire adrenal cortex
- deficiency of all hormones (mineralocorticoids, glucocorticoids and sex steroids)
Clinical features
- weight loss due to glucocorticoid deficiency, anorexia, weakness, fever, depression, low libido, impotence
- pigmentation due to ACTH (vitiligo)
- postural hypotension due to mineralocorticoids
Test for 9am cortisol levels
Treat with hydrocortisone (steroids) and fludrocortisone (synthetic aldosterone)

Question 8

Causes of primary adrenal failure

Answer 8

• TB
• surgical removal
• infarction
• infiltrative disease
• adrenal leucodystrophy

Question 9

Secondary adrenal failure

Answer 9

• inadequate ACTH production pituitary tumour

- suppression of HPA axis by long-term steroids

Question 10

Nelson’s syndrome

Answer 10

Lack of negative feedback - uncontrolled pituitary growth

Very high ATCH levels