HPA Axis: Clinical Aspects

Question 1

What types of hormones does the adrenal cortex produce?

Answer 1

• Glucocorticoids (e.g. cortisol)
• Mineralocorticoids (e.g. aldosterone)
• Sex steroids (androgens)

Question 2

What binding protein does the majority of cortisol bind to?

Answer 2

Cortisol binding globulin (90%)

Question 3

How do cortisol levels vary throughout the day?

Answer 3

Cortisol levels rise in the morning and peak just before waking up.

They then fall during the day and are low in the evenings.

This is known as circadian rhythm (levels oscillate over 24 hours)

Question 4

What do mineralocorticoid receptors have the same affinity for?

Answer 4

Aldosterone and Cortisol

Question 5

How do the kidneys ensure that the majority of mineralocorticoid receptors bind with aldosterone and not cortisol?

Answer 5

They contain 11-B-HSD-2 enzymes which inactivates cortisol into cortisone, meaning there is less cortisol available to compete with aldosterone.

Question 6

What is Cushing’s Syndrome?

Answer 6

A metabolic disorder caused by having too much cortisol

Question 7

What can Cushing’s syndrome lead to?

Answer 7

• Hypertension
• Weight gain (central obesity so not arms or legs)
• Insulin resistance
• Osteoporosis

Question 8

What can cause the excess cortisol levels that leads to Cushing’s syndrome?

Answer 8

• Pituitary adenoma (affecting corticotrophe cells)
• Adrenal tumour (adenoma)
• Steroid treatment

Question 9

What are some clinical features of Cushing’s syndrome?

Answer 9

• Central obesity
• Rounded face
• Thin skin (easily bruised)
• Hirsutism
• Diabetes
• Hypertension
• Osteoporosis
• Psychiatric problems

Question 10

What is Addison’s disease?

Answer 10

Having too little cortisol and it is usually autoimmune

Question 11

What are some clinical features of Addison’s disease?

Answer 11

• Malaise (general discomfort/pain)
• Weakness
• Weight loss
• Hypotension
• Hypoglycaemia

Question 12

Why should you never investigate for an endocrine condition in a patient unless their signs/symptoms suggest they have it?

Answer 12

Due to the risk of a false-positive

Question 13

When should you image an endocrine gland?

Answer 13

After a diagnosis has been made biochemically

Question 14

When is the only time you need to image patients with Addison’s disease?

Answer 14

When you are concerned that they may have TB or cancer

Question 15

How can Addison’s disease be managed?

Answer 15

Steroid hormone replacement therapy (glucocorticoid) and sometimes mineralocorticoids will be needed too.

Question 16

When would the doses in steroid hormone replacement therapy need to be increased?

Answer 16

In cases of stress (e.g. flu)