Mineralocorticoids

Question 1

Mineralocorticoids
synthesized in zona ???

Answer 1

glomerulosa

Question 2

regulate the electrolyte concentration of extracellular fluids

Answer 2

Mineralocorticoids

Question 3

• most important mineralocorticoid

Answer 3

Aldosterone

Question 4

Maintains Na+ balance by reducing excretion of sodium from the body

Stimulates reabsorption of Na by the kidneys and K+ excretion

Answer 4

Aldosterone

Question 5

Expands ECF volume

Answer 5

Aldosterone

Question 6

Aldosterone secretion is stimulated by:

Answer 6

Decreasing blood volume or pressure (renin-angiotensin system) is the major stimulant

Low blood Na+

Rising blood levels of K+

ACTH

Question 7

The Four Mechanisms of Aldosterone Secretion

RPAA

Answer 7

Renin-angiotensin mechanism

Plasma concentration of sodium and potassium

ACTH

Atrial natriuretic peptide (ANP)

Question 8

Renin-angiotensin mechanism
- kidneys release_____, which is converted into ______that in turn stimulates aldosterone release

Answer 8

renin

angiotensin II

Question 9

• directly influences the zona glomerulosa cells

Answer 9

Plasma concentration of sodium and potassium

Question 10

• causes small increases of aldosterone during stress

Answer 10

ACTH

Question 11

• inhibits activity of the zona glomerulosa

Answer 11

Atrial natriuretic peptide (ANP)

Question 12

Actions of Aldosterone

Stimulates sodium reabsorption by ______ and ______of the nephron and promotes potassium and hydrogen ion excretion

Increases transcription of Na/K pump
Increases the expression of apical Na channels and an Na/K/Cl cotransporter

Answer 12

distal tubule and collecting duct

Question 13

Ag-Il will act on….

Answer 13

ADH - water reabsorption
Thirst - increased
Arteriolar vasoconstriction- increased
Aldosterone - increased sodium reabsorption and potassium excretion

Question 14

Aldosterone: Role in Diseases
Complete failure to secrete aldosterone leads to ______ why??

Answer 14

DEATH

dehydration, low blood volume

Question 15

Hyperaldosterone states
• Contribute to_____ associated with increased blood volume.

Answer 15

hypertension

Question 16

Role in Diseases
Overproduction of Aldosterone

(i.e., Conn’s syndrome) adenoma, nodular hyperplasia of zona glomerulosa

Answer 16

Primary causes

Question 17

Role in Diseases
Overproduction of Aldosterone

cirrhosis, ascites, nephrotic syndrome

Answer 17

Secondary causes

Question 18

there is a unilateral adenoma (benign tumor) of the adrenal gland, causing a condition known as hyperaldosteronism

Answer 18

Conn’s syndrome

Question 19

Conn’s syndrome
there is a unilateral adenoma (benign tumor) of the adrenal gland, causing a condition known as______

Answer 19

hyperaldosteronism

Question 20

when both adrenal glands are making too much aldosterone, the condition is called________

Answer 20

bilateral adrenal hyperplasia

Question 21

bilateral adrenal hyperplasia vs conn’s syndrome

Answer 21

Conn’s - one adrenal gland is affected

Bilateral adrenal hyperplasia - both adrenal glands

Question 22

Overproduction of Aldosterone
• Treatment

Answer 22

• surgical for adenoma
• medical for hyperplasia (Spironolactone)

Question 23

an enlargement of an adrenocorticotropic hormone-producing tumor in the pituitary gland, following surgical removal of both adrenal glands

Answer 23

Nelson’s Syndrome

Question 24

PA/PRA Ratio:
• PA =
• PRA =
• A PA/PRA ratio_____is suggestive of primary aldosteronism (PA).

Answer 24

Plasma Aldosterone

Plasma Renin Activity

> 25

Question 25

Low Renin: • In primary aldosteronism, renin levels remain_____ and fail to rise even when the body experiences volume depletion (e.g., dehydration). High Aldosterone: • Aldosterone levels remain____ and are not suppressed by: • Saline infusion (which normally lowers aldosterone). • Angiotensin inhibition.

Answer 25

low high

Question 26

Upright PA/PRA Ratio Test • Why it’s done: To measure the PA/PRA ratio under two conditions. • Steps: 1. Fluid deprivation: Overnight dehydration _______in normal individuals, but PRA stays low in primary aldosteronism. 2. Volume expansion: After ***2 liters of saline over 4 hours,*** aldosterone secretion is______ in normal individuals. In PA, it remains high.

Answer 26

increases PRA (renin levels) suppressed

Question 27

• Purpose: Screens for excessive aldosterone activity based on how much potassium is excreted in urine.

Answer 27

Urinary Potassium Excretion Test

Question 28

Urinary Potassium Excretion Test • Results: •_________ : Suggests primary aldosteronism (excess aldosterone causes K⁺ loss in urine). • _________: Indicates other causes, such as diuretic use or gastrointestinal potassium loss.

Answer 28

>30 mEq/day <30 mEq/day

Question 29

Confirms aldosteronism by testing if aldosterone levels can be suppressed.

Answer 29

Captopril Suppression Test

Question 30

Captopril Suppression Test • Steps: 1. Take_____ of____ orally. 2. Measure aldosterone levels at baseline, 1 hour, and 2 hours post-captopril. Results: • High aldosterone levels: Confirms______. • Suppressed aldosterone: Points to other causes of high blood pressure.

Answer 30

50 mg; captopril aldosteronism

Question 31

Additional Confirmatory Tests : Tests if a high sodium diet suppresses aldosterone. : Administers saline to suppress aldosterone. : Uses a synthetic mineralocorticoid to evaluate aldosterone secretion.

Answer 31

Oral Sodium Loading Test Saline Infusion Test Fludrocortisone Suppression Test

Question 32

Results: •______: Suggests either: • Aldosterone-producing adenoma (APA). • Idiopathic hyperaldosteronism (IHA).

Answer 32

18-Hydroxycorticosterone Measurement >100 ng/dL

Question 33

to detect tumors or hyperplasia

Answer 33

CT scan or MRI

Question 34

to detect tumors or hyperplasia

Answer 34

CT scan or MRI

Question 35

ACTH • Pulsatile fashion Diurnal variation • Highest - • Lowest - • Protein-rich meals

Answer 35

2:00 am - 4:00 am 8:00 am 10:00 pm - 12 mn