Diuretics

Question 1

What is an example of an osmotic diuretic?

Answer 1

Mannitol, possibly glucose

Question 2

What is acetazolamide?

Answer 2

A carbonic anhydrase inhibitor

Question 3

What are some examples of thiazide diuretics?

Answer 3

Hydrochlorothiazide, metolazone

Question 4

What are some examples of loop diuretics?

Answer 4

Furosemide, bumetanide, ethacrynic acid (non-sulfonamide)

Question 5

What are some examples of potassium sparing diuretics?

Answer 5

Spironolactone, eplerenone

Question 6

What is conivaptan?

Answer 6

An anti-diuretic hormone antagonist

Question 7

What is dapaglifozin?

Answer 7

A sodium glucose transport inhibitor

3rd line drug

Question 8

What is a diuretic?

Answer 8

An agent that increases urine flow to block sodium reabsorption/increase sodium excretion

Question 9

What is the typical GFR?

Answer 9

100-120 ml/min

Question 10

What occurs in the proximal tubule?

Answer 10

Glucose and HCO3 (bicarbonate) are reabsorbed

Question 11

What occurs in the ascending loop of henle?

Answer 11

Na, K and 2 Cl are pumped out and Ca and Mg follow

Water is not reabsorbed

Question 12

What occurs in the distal tubule?

Answer 12

NaCl is reabsorbed

Ca is excreted

Question 13

What occurs in the collecting ducts?

Answer 13

Water is reabsorbed in the presence of ADH (vasopressin) to concentrate urine
Na is reabsorbed while K is excreted when aldosterone is present

Question 14

What are osmotic diuretics?

Answer 14

Osmotically active (hold onto water) compounds in the plasma. Stops water reabsorption, giving a high urine volume with little sodium
Filtered, not reabsorbed, pharmacologically inert and resistant to alteration
Mannitol, glucose

Question 15

What can osmotic diuretics be used for?

Answer 15

Mannitol (IV), glycerol (oral) used for vascular surgery, renal transplant and opthalmological procedures

Question 16

How can glucose become an osmotic diuretic?

Answer 16

In diabetes mellitus, there is so much glucose in the blood that it is not all reabsorbed in the proximal tubule. The glucose goes to parts of the kidney that have never seen it and holds onto water.

Question 17

What are carbonic anhydrase inhibitors?

Answer 17

Very weak diuretics that inhibit carbonic anhydrase. Thus decreases HCO3 reabsorption and increases HCO3 excretion (with some Na) in proximal tubule
Acetazolamide

Question 18

What are the uses of carbonic anhydrase inhibitors?

Answer 18

Severe alkalosis
Alkalinization of filtrate ionizes acidic drugs (increases renal excretion of aspirin)
Glaucoma

Question 19

What is acute mountain sickness?

Answer 19

When someone goes to high altitudes and they hyperventilate due to the decreased oxygen. This causes decreased CO2 (increased bicarbonate)

Question 20

What do thiazide diuretics do?

Answer 20

Increase NaCl excretion and decrease Ca excretion in the distal tubule (opposite of loop diuretics)
Some proximal tubular effect, only important when combined with loop
Hydrochlorothiazide
Up to 5% off filtered load

Question 21

How does dose of thiazide diuretics affect its effect?

Answer 21

Lower dose is just as effective as higher dose, just takes longer to work. Will have fewer side effects.

Question 22

What can thiazide diuretics do to blood pressure?

Answer 22

May decrease blood pressure with decreased blood volume and cardiac output. An apparent tolerance occurs (no diuresis) as blood volume and Co return to normal. But blood pressure stays low or lowers due to the decreased peripheral resistance (vasodilation)

Question 23

What are the advantages of using a thiazide diuretic?

Answer 23

It is orally active with low toxicity. Gives no postural hypotension.
Can potentiate other antihypertensive drugs

Question 24

What problems could thiazide diuretics cause?

Answer 24

Hyperglycemia due to decreased insulin release and tissue utilization
Increased LDL levels
Erectile dysfunction
Hypovolemia

Question 25

What happens due to hypovolemia?

Answer 25

Increased proximal tubule reabsorption which could increase lithium and urea (bad for gout) absorption

Question 26

What are thiazide diuretics used for?

Answer 26

Edema and hypertension

Question 27

What do loop diuretics do?

Answer 27

Increase prostaglandin production (vasodilation) | Increases Na, Cl, K and Mg excretion

Question 28

Should loop diuretics be used for a long period of time? Why?

Answer 28

Not too long. They are very potent and efficacious high ceiling diuretics (up to 20% off filtered load) which could cause too much fluid loss.

Question 29

What diuretic can be used in acute pulmonary edema?

Answer 29

Loop diuretics due to venous vasodilation

Question 30

What drug can decrease the function of loop and thiazide diuretics?

Answer 30

NSAIDS

Question 31

What might loop diuretics do to the urine? How?

Answer 31

The kidney may lose the ability to dilute or concentrate the urine, making it isotonic. If you drink a lot water, it will excrete electrolytes to make it isotonic

Question 32

What problems can loop diuretics cause?

Answer 32

Deafness when combined with aminoglycoside antibiotics | Chronic dilutional hyponatremia due to isotonic urine

Question 33

What are loop diuretics used for?

Answer 33

For renal insufficiency (GFR

Question 34

What do you do if a patient is not responding to a loop diuretic?

Answer 34

If refractory, add a thiazide diuretic because their blocking in the proximal tubule increases the delivery to the loop, giving the loop diuretic something to block

Question 35

What are the 2 major causes of potassium depletion?

Answer 35

Secondary hyperaldosteronism and increased distal delivery

Question 36

How can secondary hyperaldosteronism cause potassium depletion?

Answer 36

Plasma volume depletion causes an increase in renin which thus causes the activation of angiotensin II and increases aldosterone. This causes pumps to work to reabsorb Na at the expense of K

Question 37

How can increased distal delivery cause a postassium depletion?

Answer 37

The increased distal delivery is due to inhibition of Na reabsorption in the loop and distal tubule Collecting tubules will then increase Na reabsorption to conserve sodium

Question 38

How can potassium depletion be treated?

Answer 38

``` Dietary intake (apricots, bananas)-not helpful KCl tablets Slow K tablets IV 40 meq KCl in emergencies K sparing diuretics ```

Question 39

What are potassium sparing diuretics?

Answer 39

Weak diuretics given with other diuretics to decrease K loss but may cause hyperkalemia Never combine with K supplements Work is collecting tubule

Question 40

What do spironolactone and eplerenone do?

Answer 40

Blocks aldosterone receptor which causes reabsorption of Na at expense of K.

Question 41

What does triamterene do?

Answer 41

Decrease sodium permeability so K is not excreted.

Question 42

What else can increase plasma K levels?

Answer 42

beta-adrenoceptor antagonists, ACE inhibitors and ARBs

Question 43

What do ADH antagonists do?

Answer 43

Blocks the ADH receptor in the collecting tubules so vasopressin is unable to increase water reabsorption. Thus increases water excretion without the electrolytes

Question 44

What happens to vasopressin in heart failure and syndrome of inappropriate ADH secretion (SIADH)?

Answer 44

Vasopressin is increased, so there is chronic increased water reabsorption which can produce hyponatremia

Question 45

What are ADH antagonists used for?

Answer 45

Syndrome of inappropriate ADH secretion (SIADH) when water restriction alone is not effective

Question 46

What is nephrogenic diabetes insipidus?

Answer 46

Increased urine flow due to the lack of a renal effect of ADH Bitter urine

Question 47

What do sodium glucose co-transport 2 (SGLT2) inhibitors do?

Answer 47

Blocks the sodium glucose cotransporter in the proximal tubule to increase glucose excretion. Causes small decrease in blood glucose

Question 48

What causes sodium and extracellular volume depletion?

Answer 48

Inability of kidney to concentrate or dilute urine (isotonic urine) due to furosemide Inability to concentrate urine (save water) -Drink more wayer to excrete solutes Inability to dilute urine (excrete excess water)-Ingest hypotonic solution

Question 49

What should be done in the case of hypocalciuria?

Answer 49

Use thiazide diuretics to decrease Ca excretion | Use in the case of stones in the ureter

Question 50

What should be done in the case of hypercalcemia?

Answer 50

Use furosemide to increase Ca excretion

Question 51

What happens during volume depletion and increased proximal tubule reabsorption?

Answer 51

Uric acid excretion is initially increased but then decreased The proximal reabsorption of lithium is increased (toxic)

Question 52

What does it mean if edema is present?

Answer 52

Fluid shift into the extra cellular space has exceeded 3-4L Salt and water retention Congestive heart failure, hepatic cirrhosis, renal failure

Question 53

What is the first line therapy for hypertension?

Answer 53

Thiazide diuretic or good as a second medication

Question 54

What occurs during cardiac failure?

Answer 54

Decreased blood pressure (kidney retains Na and H2O) causing increased intravascular volume and increased left ventricular filling pressure (but decreased contractility) and increased pulmonary and venous pressure (loop diuretic useful)