Adrenal Cortex

Question 1

What are the three main hormones secreted by the adrenal cortex?

Answer 1

1. Glucocorticoids → Cortisol (glucose metabolism, immune suppression, stress response).
2. Mineralocorticoids → Aldosterone (sodium and potassium balance, blood pressure).
3. Androgens → DHEA, DHEA-S, and testosterone (male secondary sexual characteristics).

Question 2

What is the role of glucocorticoids (Cortisol)?

Answer 2

• Increases blood glucose (stimulates gluconeogenesis).
• Breaks down proteins (catabolism).
• Redistributes fat (central obesity in Cushing’s syndrome).
• Suppresses immune system (anti-inflammatory effect).
• Decreases calcium absorption (leads to osteoporosis).
• Regulates circadian rhythm (peaks in the morning, lowest at midnight).

Question 3

What is the role of mineralocorticoids (Aldosterone)?

Answer 3

• Increases sodium retention → Raises blood pressure.
• Promotes potassium & hydrogen excretion → Prevents hyperkalemia.

Question 4

What is the role of adrenal androgens (DHEA & DHEA-S)?

Answer 4

• Contribute to male secondary sexual characteristics.
• Have weak androgenic effects but convert into testosterone in peripheral tissues.

Question 5

What blood tests assess glucocorticoid function?

Answer 5

• Morning Cortisol (8 AM sample): 250–600 nmol/L (higher in the morning).
• ACTH Levels (EDTA tube, stored on ice): 10–80 ng/L.
• Urinary Free Cortisol (24-hour collection): <100 µg/24h.

Question 6

What urine tests assess adrenal function?

Answer 6

• 17-Hydroxy Steroids (17-OH steroids): Reflects cortisol metabolism.
• 17-Ketosteroids (17-KS steroids): Reflects adrenal androgens & testosterone precursors.

Question 7

What tests assess mineralocorticoid function?

Answer 7

• Plasma Aldosterone: Normal range: 20-40 nmol/24h.
• Plasma Renin Activity (PRA): Essential for aldosterone interpretation.
• Electrolyte Panel:
  
  • Hyperaldosteronism: ↓ K+, ↑ Na+, metabolic alkalosis.
  • Hypoaldosteronism: ↑ K+, ↓ Na+, metabolic acidosis.

Question 8

What is the Synacthen (ACTH) Stimulation Test, and what does it diagnose?

Answer 8

• Used to diagnose adrenal insufficiency (Addison’s disease).
• Procedure: Inject synthetic ACTH → Measure cortisol before & after 30-60 min.
• Normal: Cortisol ↑ >500 nmol/L.
• Primary adrenal insufficiency: Low cortisol, high ACTH.
• Secondary adrenal insufficiency: Low cortisol, low ACTH.

Question 9

What is the Dexamethasone Suppression Test (DST), and what does it diagnose?

Answer 9

• Used to diagnose Cushing’s syndrome.
• Procedure: Give 1 mg dexamethasone at midnight → Measure cortisol at 8 AM.
• Normal: Cortisol suppression (<50 nmol/L).
• Cushing’s syndrome: No suppression (>138 nmol/L).

Question 10

What is the Saline Infusion Test, and what does it diagnose?

Answer 10

• Used to diagnose primary hyperaldosteronism (Conn’s syndrome).
• Procedure: Infuse 2L saline over 4 hours → Measure aldosterone.
• Normal: Aldosterone suppression.
• Conn’s syndrome: Aldosterone remains high.

Question 11

What is the Orthostatic Stimulation Test, and what does it differentiate?

Answer 11

• Used to differentiate adrenal hyperplasia from Conn’s adenoma.
• Procedure: Measure aldosterone & renin before & after standing.
  
  • Increase in aldosterone: Adrenal hyperplasia.
  • No increase in aldosterone: Conn’s adenoma.

Question 12

What are the causes of Cushing’s syndrome?

Answer 12

• ACTH-Dependent: Pituitary adenoma (Cushing’s disease).
• ACTH-Independent: Adrenal adenoma or carcinoma.

Question 13

What are the key clinical features of Cushing’s syndrome?

Answer 13

• Central obesity, moon face, buffalo hump.
• Hypertension & hyperglycemia.
• Osteoporosis, muscle weakness.
• Skin thinning, purple striae.

Question 14

How do you confirm Cushing’s syndrome?

Answer 14

• 1 mg overnight dexamethasone suppression test: No cortisol suppression.
• 24-hour urinary free cortisol: ↑ cortisol excretion.

Question 15

What are the causes of adrenal insufficiency?

Answer 15

• Primary (Addison’s disease): Autoimmune, infections (TB), adrenal hemorrhage.
• Secondary: ACTH deficiency (pituitary disorder) or prolonged corticosteroid use.

Question 16

What are the symptoms of Addison’s disease?

Answer 16

• Hyperpigmentation (only in primary adrenal insufficiency).
• Fatigue, hypotension, weight loss.
• Hyponatremia, hyperkalemia, metabolic acidosis.

Question 17

What test confirms Addison’s disease?

Answer 17

Synacthen (ACTH Stimulation) Test: No cortisol response.

Question 18

What are the causes of primary hyperaldosteronism?

Answer 18

• Aldosterone-producing adrenal adenoma (Conn’s syndrome).
• Bilateral adrenal hyperplasia.

Question 19

What are the symptoms of primary hyperaldosteronism?

Answer 19

Hypertension, hypokalemia, metabolic alkalosis, low renin.

Question 20

How do you diagnose Conn’s syndrome?

Answer 20

• Saline Infusion Test: No aldosterone suppression.
• Plasma Aldosterone/Renin Ratio (ARR): High aldosterone, low renin.

Question 21

What are the causes of adrenal hyperandrogenism?

Answer 21

• Congenital adrenal hyperplasia (21-hydroxylase deficiency).
• Adrenal tumors.

Question 22

What are the symptoms of adrenal hyperandrogenism?

Answer 22

• Virilization in females (hirsutism, deep voice).
• Ambiguous genitalia in newborns.

Question 23

What biochemical findings suggest congenital adrenal hyperplasia?

Answer 23

• ↑ 17-OH progesterone.
• ↓ Cortisol, ↑ ACTH.