Diuretics

Question 1

Where do loop diuretics act?

Answer 1

The thick ascending limb of the loop of Henle

Question 2

Mechanism of action of loop diuretics?

Answer 2

Block the triple co-transporter

Question 3

What do loop diuretics do?

Answer 3

Prevent dilution of the filtrate in the TAL, increasing the load of Na+ reaching the late nephron

Question 4

How do loop diuretics enter the nephron?

Answer 4

OAT

Question 5

Example of a loop diuretic?

Answer 5

Furosemide

Question 6

Indications for loop diuretic use?

Answer 6

Nephrotic syndrome
Acute hypercalcaemia
Hypertension
Chronic heart/kidney failure

Question 7

Cons of loop diuretics?

Answer 7

Hypovolaemia
Hypotension
Calcium and magnesium depletion
Hypokaleamia

Question 8

Where do thiazide diuretics act?

Answer 8

Early distal tubule

Question 9

Mechanism of action of thiazide diuretics?

Answer 9

Block Na+/Cl- cotransporter

Question 10

What do thiazide diuretics do?

Answer 10

Increase Na+ load reaching the late nephron

Increase calcium reabsorption

Question 11

How do thiazide diuretics enter the nephron?

Answer 11

OAT

Question 12

Example of a thiazide diuretic?

Answer 12

Bendroflumethiazide

Question 13

Indications for thiazide diuretic use?

Answer 13

Mild heart failure
Hypertension
Renal stone disease
Nephrogenic diabetes insipidus

Question 14

Cons of thiazide diuretics?

Answer 14

Hypovolaemia
Hypotension
Hypokalaemia
Magnesium depletion

Question 15

Where do osmotic diuretics act?

Answer 15

Proximal tubule

Question 16

How do osmotic diuretics enter the nephron?

Answer 16

Filtration

Question 17

Mechanism of action of osmotic diuretics?

Answer 17

Increase the filtrate osmolarity, opposing the reabsorption of water

Question 18

Example of an osmotic diuretic?

Answer 18

Mannitol

Question 19

Indications for use of osmotic diuretics?

Answer 19

Acute raised ICP/IOP

To prevent hypovolaemic renal failure to maintain urine flow

Question 20

Cons of osmotic diuretics?

Answer 20

Secondary hyponatraemia - increased fluid volume decreases sodium concentration and the gradient for its reabsorption

Question 21

Examples of potassium sparing diuretics?

Answer 21

Spironolactone

Amiloride

Question 22

Mechanism of action of amiloride?

Answer 22

Blocks apical Na+ channels

Question 23

Mechanism of action of spironolactone?

Answer 23

Competes with aldosterone, reducing Na+ reabsorption

Question 24

What do potassium sparing diuretics do?

Answer 24

Increase Na+ excretion and decrease K+ excretion

Question 25

Indications for potassium sparing diuretic use?

Answer 25

Hypertension Heart failure Primary and secondary hyperaldosteronism

Question 26

Cons of spironolactone?

Answer 26

Gynaecomastia

Question 27

How do carbonic anhydrase inhibitors work?

Answer 27

Increase bicarbonate excretion along with Na+, K+ and H2O

Question 28

Cons of carbonic anhydrase inhibitors

Answer 28

Cause an alkaline urine and metabolic acidosis

Question 29

No longer used as diuretics but used instead for:

Answer 29

Glaucoma Altitude sickness prophylaxis Infantile epilepsy

Question 30

Where do carbonic anhydrase inhibitors act?

Answer 30

Proximal tubule

Question 31

Example of carbonic anhydrase inhibitor?

Answer 31

Acetazolamide