Lecture 22: Steroid abnormalities

Question 1

Glucocorticoid deficiency?

Answer 1

Eg. CORTISOL - WATER RETENTION w NO SALT LOSS

Hyponatremia

• Decreased Na⁺ conc from inability to excrete water overload. Reduced GFR and loss of cortisol inhibition of ADH

Hypoglycaemia

• Decreased glucose due to decreased liver function (hepatic gluconeogenesis)

Hypotension

• Loss of cortisol effects on vascular tone
• leads to decreased perfusion leading to decreased GFR resulting in decreased excretion = decreased [Na⁺] = AKI

Question 2

Mineralocorticoid deficiency?

Answer 2

Eg. Aldosterone (normally regulates extrvascular fluid volume) = SALT LOSS, THEN WATER RETENTION

Hyponatremia

• urine Na⁺ loss with intravascular volume contraction and secondary ADH secretion (turns on when 8% lost because you would rather have a low conc of water than no blood volume)

Hypotension

• Na lost in urine lowers BV = lowers BP = increased ADH = retention of water = hyponatremia

Metabolic acidosis

• Increased H⁺ levels due to reduced renal excretion

Hyperkalaemia

• ​Due to reduced renal excretion

Question 3

Adrenal gland failure causes?

Answer 3

primary (adrenal gland) and secondary (pituitary/hypothalamus)

Question 4

Primary adrenal problems lead too?

Answer 4

• Decreased cortisol (normally inhibits Hypothalamus and pituitary)
• leads to increased CRF and subsequentially ACTH
• ACTH is a product of POMC which also makes MSH (melanocyte stimulating hormone) = TAN

Increased pigmentation:

• Skin flexures
• Buccal mucosa
• Old scars
• Freckles
• nails

Question 5

When is obesity simple or not?

Answer 5

• Change in appearance over time
• Growth pattern (fat kids will likely also grow taller than they should and enter puberty earlier finishing up where they should)
• Glucocorticoid excess causes profound growth failure
• other features of pathalogical causes

A short fat kid has an underlying cause until proven otherwise

Question 6

Glucocorticoid excess features?

Answer 6

Moon Face

Thinning skin - facial plethora, bruising

Androgen excess - Hirsutism, amenorrhoea

Myopathy - proximal weakness (hips, shoulders)

glucose intolerance - Diabetes mellitus

Question 7

Cause of low Renin in excess cortisol?

Answer 7

You would think that low renin would be from aldosterone incresing ECV, you will see that K is also low (you would expect it to be low with Aldosterone)

BUT

When cortisol levels get so high they overload their receptors and have a mineralocorticoid effect leading to hypertension and hypokalaemia

Classical of CUSHINGS caused by:

• Primar functional adrenal tumour
• ATCH secreting tumour
• exogenous glucocorticoid (steriod cream)

Question 8

What would partial loss of function of the glucocorticoid receptor cause?

Answer 8

• The brain is going to release ACTH and CRF causing more cortisol
• Will bind to mineralocorticoid receptors (hypertension, low K)
• Will get really sick - fatigue
• Hyperandrogenism (amenorrhoea, hirsutism)

Question 9

Loss of mineralocorticoid receptor?

Answer 9

will look like aldosterone deficiency

BUT - measured levels would be HIGH (as well as renin)

leads to depleted extracellular fluid space, high K and low Na conc

Question 10

Loss of ACTH receptor function?

Answer 10

Can’t make cortisol - looks like no adrenal function

• Hypotension
• Low Na
• Hypoglycaemia