3.A-Diuretics

Question 1

True or false: hypertension is usually a multifactorial problem

Answer 1

true

Question 2

How can the kidney play a role in hypertension?

Answer 2

fail to eliminate enough fluid–>fluid builds up in vessels–>blood pressure increase

Question 3

If you were to explain to someone with zero knowledge about diuretics, how would you explain diuretics to them?

Answer 3

diuretics increase urine production to help reduce blood pressure
they block the reabsorption of sodium
more Na in the urine=more fluid excreted

Question 4

Which parts of the nephron are responsible for Na+ reabsorption? (state the % of Na+ reabsorbed in each part)

Answer 4

proximal tubule (65%)
ascending loop of Henle (25%)
distal tubule (very little)

Question 5

What is the major driver of fluid retention?

Answer 5

sodium reabsorption

Question 6

True or false: the kidney filters 120ml/min, makes urine at 1ml/min, thus 99% of filtered fluid is reabsorbed

Answer 6

true

Question 7

What structure connects the afferent arteriole and ascending loop of Henle? What does this structure do?

Answer 7

macula densa
it senses Na+ concentrations in the nephron

Question 8

Describe tubuloglomerular feedback.

Answer 8

occurs at the macula densa cells
an increased concentration of Na at the macula densa cell causes vasoconstriction at the afferent arteriole
(high Na will decrease renal blood flow)

Question 9

True or false: all diuretics have impact on blood pressure

Answer 9

false

Question 10

List the classes of diuretics.

Answer 10

loop diuretics
thiazide diuretics
potassium-sparing diuretics
carbonic anhydrase diuretics
osmotic diuretics

Question 11

Where do loop diuretics act?

Answer 11

ascending loop of Henle (Na-K-2Cl symport inhibitors)

Question 12

True or false: loop diuretics block the reabsorption of Na only

Answer 12

false
they block the reabsorption of Na and Cl

Question 13

What is the significance of blocking the reabsorption of Cl with loop diuretics?

Answer 13

less Cl in the interstitial space means less force to draw in Ca and Mg

Question 14

What are some undesirable actions of loop diuretics?

Answer 14

Ca and Mg loss due to loss of electrical gradient that is normally causing by the reabsorption of Cl
K loss in urine due to RAAS
uric acid retention in blood

Question 15

What are the loop diuretics listed in the Sask Formulary?

Answer 15

furosemide
bumetanide
ethacrynic acid

Question 16

Why are loop diuretics not ideal for bp control?

Answer 16

short half life
potent stimulator of kidney activation
-RAAS activation
-single dose can result in over correction

Question 17

Normally loop diuretics are not ideal for bp control, what is the exception?

Answer 17

patients with poor kidney function
-half life is prolonged
-blood pressure effect is more stable

Question 18

Where do thiazide diuretics act?

Answer 18

distal tubule (Na-Cl symport inhibitors)

Question 19

True or false: thiazide diuretics are weaker than loop diuretics because there is less Na reabsorbed in the distal tubule

Answer 19

true
location of action matters!!!

Question 20

What are some differences that thiazides have compared to loops in regards to how they effect ions and blood pressure?

Answer 20

thiazides:
-Ca can increase with long term use
-Mg loss occurs but less likely than loops
-better for bp control

Question 21

What are the thiazide diuretics listed in the Sask Formulary?

Answer 21

chlorthalidone
hydrochlorothiazide
indapamide
metolazone

Question 22

At what GFR should thiazide diuretics not be used?

Answer 22

<30-40ml/min

Question 23

List off the common uses of TZD and loop diuretics.

Answer 23

high blood pressure: thiazides
high blood pressure in ppl with kidney disease: loops
heart failure: loop and thiazides

Question 24

What are the electrolyte problems with Na blocking diuretics?

Answer 24

hypokalemia (low K)
hyponatremia (low Na)
hypochloremia (low Cl)
hypomagnesemia (low Mg)
calcium (increases with TZDs, decreases with loops)

Question 25

What are the impacts on plasma metabolites and hemodynamics with Na blocking diuretics?

Answer 25

plasma metabolites:
-hyperuricemia (increased risk for gout)
-decreased glucose tolerance=increased blood glucose

hemodynamic effects:
-hypotension (cause of dizziness)
-reduced renal perfusion
-increased activity of RAAS

Question 26

Hypokalemia is known to be the most common electrolyte imbalance with Na blocking diuretics, what else can increase the risk for hypokalemia?

Answer 26

low K intake
receiving other K depleting drugs
accelerated loss (vomiting/diarrhea)

Question 27

Where do K-sparing diuretics act?

Answer 27

late distal tubule and collecting duct (inhibit ENaCs)
-decreased Na absorption exaggerates the polarization of the
epithelial membrane
-discourages K excretion

Question 28

How are K sparing diuretics mainly used in practice?

Answer 28

to prevent K decreased during diuretic therapy
commonly combined with a loop or TZD

Question 29

What are the K sparing diuretics listed in the Sask Formulary?

Answer 29

triamterine
amiloride

Question 30

Describe carbonic anhydrase inhibitors.

Answer 30

not effective diuretics
typically used for glaucoma
prevent the reabsorption of NaHCO3

Question 31

Describe osmotic diuretics.

Answer 31

freely filtered with little reabsorption
create an osmotic effect to keep water in urine
typically only used in hospital

Question 32

What are the agents used as osmotic diuretics?

Answer 32

glycerin
mannitol
urea

Question 33

What rate (ml/min) does the kidney filter at?

Answer 33

filters 120ml/min
makes urine at 1ml/min

Question 34

Which diuretic acts at the proximal tubule?

Answer 34

there are none that act at the proximal tubule

Question 35

Why are certain diuretics used to lower blood pressure?

Answer 35

high blood pressure often involves increased blood volume

Question 36

What is the most common electrolyte deficiency with Na blocking diuretics?

Answer 36

hypokalemia

Question 37

How strong is the diuretic effect of K sparing diuretics?

Answer 37

very weak (little Na is reabsorbed by the distal tubule)

Question 38

What is the main benefit of the carbonic anhydrase pathway?

Answer 38

enables re-absorption of HCO3- (critical buffer)