endocrinology 2

Question 1

Adrenal Gland - Overview

Answer 1

triangular-shaped glands located on top of both

kidneys

Question 2

adrenal cortex produces three types of steroid hormones

Answer 2

1) Mineralocorticoids
2) Glucocorticoids
3) Androgens

Question 3

Mineralocorticoids

Answer 3

• Bind to the mineralocorticoid receptor (MR) in the distal convoluted
tubule and collecting ducts of the nephron, the colon, and the salivary
glands
• Regulate salt and water balance
• Promote Na+ reabsorption and K+ and H+ excretion

EX) Aldosterone

Question 4

Glucocorticoids

Answer 4

• Bind to the glucocorticoid receptor (GR) expressed in different tissues such as
lymphocytes, hepatocytes, and bone.
• Regulate metabolism of fat, proteins, and carbohydrates

EX) Cortisol

Question 5

Androgens

Answer 5

• Regulate sexual development
• Dehydroepiandrosterone (DHEA)* and Androstenedione*

• The adrenal medulla produces hormones called catecholamines.

• Produced as a reaction to stress.
• Main catecholamines: epinephrine* (adrenaline), norepinephrine, and dopamine

Question 6

Adrenal Cortex Disorders - Addison Disease (Primary Adrenal Insufficiency)

Answer 6

• Deficiency of mineralocorticoid aldosterone* (hypoaldosteronism) and glucocorticoid cortisol*

• Signs/Symptoms:
  
  • Weakness
  • Hypotension
  • Hyperpigmentation of skin
  • Weight loss

• Lab Findings:
    ↓ Aldosterone
    ↓ Na+ and Cl-
    ↓ Cortisol
    ↓ Hgb (anemia)
    ↑ ACTH

• ACTH = adrenocorticotropic hormone
• Corticotropin-releasing hormone (CRH) released from the hypothalamus stimulates secretion of ACTH from the anterior pituitary gland.
• Regulates cortisol hormone levels

Question 7

Adrenal Cortex Disorders - Conn Syndrome (Hyperaldosteronism)

Answer 7

• Excess secretion of mineralocorticoid aldosterone from adrenal glands.

• Signs/Symptoms:
- Hypertension

• Lab Findings:
↑ Na+
↓ K+
↓ Plasma renin

Question 8

Adrenal Cortex Disorders - Cushing Syndrome

Answer 8

Excessive production of the glucocorticoid cortisol*

 Signs/Symptoms:
• Hypertension
• Moon face
• Abdominal obesity
• Weakness
• Osteoporosis

 Lab Findings:
• ↑ Cortisol
• ↑ Aldosterone
• ↑ Na+
• Diabetes mellitus

Question 9

Adrenal Cortex Disorders - Cushing Syndrome screening tests

Answer 9

• 24-hour urinary free cortisol (UFC)

• <2% of secreted cortisol appears in urine as free cortisol
• Excretion of < 1380 nmol/d excludes diagnosis of Cushing syndrome

• Dexamethasone suppression test

• Measures the response of the adrenal glands to ACTH
• Patient is given dexamethasone to suppress cortisol production and cortisol is measured

• Interpretation:

• Increased cortisol (no suppression) = Cushing Syndrome
• Decreased cortisol (suppression) = Normal response

• Salivary cortisol

Question 10

Adrenal Medulla Disorders - Overview

Answer 10

• The adrenal medulla is the thin inner layer of the adrenal glands
- Contain chromaffin cells

• Hormones are produced in the chromaffin cells.( response to stress)

• Epinephrine, norepinephrine, and dopamine
• Homovanillic acid (HVA) - a metabolite of dopamine
• Metanephrines and vanillylmandelic acid (VMA) - metabolites of epinephrine