Diuretics - Loop

Question 1

Where in the kidneys is blood filtered to form the filtrate?

1 - efferent arteriole
2 - afferent arteriole
3 - glomerulus
4 - juxtaglomerular

Answer 1

3 - glomerulus

Question 2

Once the filtrate is formed from the glomerulus, what happens to the fluid as it move through the tubules and out of the collecting duct as urine?

1 - only glucose is reabsorbed
2 - Na+ and K+ only are reabsorbed
3 - lots of ions and fluids are reabsorbed

Answer 2

3 - lots of ions and fluids are reabsorbed

• H2O, ions (K+, Na+, Cl-)
• what is left is urine

Question 3

Labels the parts of the renal tubules using the labels below:

1 - loop of henle
2 - distal convoluted tubule
3 - proximal tubule
4 - collecting duct

Answer 3

1 - proximal tubule
2 - loop of henle
3 - distal convoluted tubule
4 - collecting duct

Question 4

Where are ions mainly re-absorbed in the renal system?

1 - loop of henle
2 - distal convoluted tubule
3 - proximal tubule
4 - collecting duct

Answer 4

3 - proximal tubule

• glucose, amino acids, ions, uric acid
• excretion of phosphate and H+

Question 5

Water passively follows ion re-absorption in the distal tubules of the renal system, which ion specifically does it follow?

1 - Na+
2 - K+
3 -Cl-
4 - HCO3-

Answer 5

1 - Na+
- due to osmosis (H2O dilutes Na+ in blood)

Question 6

What are diuretics?

1 - drugs that increase water, Na+ and Cl- excretion
2 - drugs that decrease water, Na+ and Cl- excretion
3 - drugs that increase water, K+ excretion
4 -drugs that decrease water, K+ excretion

Answer 6

1 - drugs that increase water, Na+ and Cl- excretion

• reduce fluid retention

Question 7

Which of the following is not part of the loop of henle?

1 - thin descending loop of henle
2 - u-bend of henle
3 - thin ascending loop of henle
4 - thick ascending loop of henle

Answer 7

2 - u-bend of henle

• does not exist

Question 8

Loop diuretic have their action by affecting the loop of henle. Specifically which part of the loop of henle do they have have their greatest effect?

1 - thin descending loop of henle
2 - thin ascending loop of henle
3 - thick ascending loop of henle

Answer 8

3 - thick ascending loop of henle

Question 9

The thick ascending loop of henle is impermeable to what?

1 - Na+
2 - K+
3 - Cl-
4 - H2O

Answer 9

4 - H2O

Question 10

The thick ascending loop of henle is impermeable to H2O. What type of channel is on the apical surface (closer to the lumen)?

1 - Na+/K+ ATPase
2 - Na+/K+/2Cl-
3 - Na+
4 - K+/Cl-

Answer 10

2 - Na+/K+/2Cl-

• moves 1 Na+ and K+ and 2 Cl- into the cells down the concentration gradient

Question 11

The thick ascending loop of henle is impermeable to H2O. Na+/K+/2Cl- channels are present on the apical surface (closer to the lumen) that move 1 Na+ and K+ and 2 Cl-. On the basolateral side of the tubules there is a Na+/K+ ATPase. What does this do?

1 - exchanges 1 Na+ for 1K+
2 - exchanges 2 Na for K+ and 2Cl-
3 - exchanges 3 Na+ for 2 K+
4 - exchanges 2 Cl- for 1 Na+

Answer 11

3 - exchanges 3 Na+ for 2 K+

• requires ATP
• K+ and Cl- are able to leak back to into the lumen via leak channels

Question 12

Through the reabsorption of Na+, K+ and Cl- an electrical gradient is generated allowing paracellular reabsorption of which 2 ions?

1 - Ca2+
2 - Cl-
3 - Mg2+
4 - Zinc

Answer 12

1 - Ca2+

3 - Mg2+

Question 13

Which 2 of the following are the loop diuretics that we need to be aware of?

1 - Bumetanide
2 - Furosemide
3 - Indapamide
4 - Bendroflumethiazide

Answer 13

1 - Bumetanide
2 - Furosemide

Question 14

Bumetanide and Furosemide are the loop diuretics that we need to be aware of. What is the mechanism of action of these drugs?

1 - inhibit Na+/K+ ATPase
2 - inhibit leaky K+/Cl- channels
3 - inhibit Na+ channels on arteries
4 - inhibit Na+/K+/2Cl- channels

Answer 14

4 - inhibit Na+/K+/2Cl- channels

• Na+, K+ and Cl- are excreted
• Ca2+ and Mg2+ are also excreted
• H2O follows the Na+

Question 15

Which of the following is NOT increased in the excretion found in the urine?

1 - Na+
2 - K+
3 - Ca2+ and Mg2+
4 - glucose
5 - Cl-

Answer 15

4 - glucose

• remember ‘Loops Loose Calcium’

Question 16

In addition to inhibiting the Na+/K+/2Cl- channels in the thick ascending loop of henle, loop diuretics Bumetanide and Furosemide have a second mechanism, what is this?

1 - vasoconstrict the efferent arteriole via prostaglandin release
2 - vasoconstrict the afferent arteriole via prostaglandin release
3 - vasoconstrict the efferent arteriole via prostaglandin release
4 - vasodilate the efferent arteriole via prostaglandin release

Answer 16

4 - vasodilate the efferent arteriole via prostaglandin release

• increases renal plasma flow
• increases eGFR
• this increases further loss of - Na+, K+, Cl-, Ca2+, Mg2+ and H2O

Question 17

Loop diuretics, Bumetanide and Furosemide, have 2 mechanisms:

• inhibiting the Na+/K+/2Cl-
• vasodilate the efferent arteriole via prostaglandin release

Which drug class can cause a dampening of this prostaglandin release, and this attenuate the effect of loop diuretcis?

1 - Antiarrhythmics
2 - NSAIDs
3 - anti-hypertensives
4 - Anticoagulants

Answer 17

2 - NSAIDs

Question 18

Which of the following is indicated alongside oxygen and nitrates in the treatment breathlessness in acute pulmonary oedema?

1 - Bumetanide or Furosemide
2 - Doxazosin
3 - Amlodipine
4 - Ramipril

Answer 18

1 - Bumetanide or Furosemide

• also though to dilate capacitance veins, reducing preload and improving cardiac function

Question 19

Loop diuretics, Bumetanide and Furosemide are indicated in 2 of the following, which 2?

1 - chronic heart failure
2 - 1st line anti-hypertension
3 - adrenal insufficiency
4 - renal and/or liver failure

Answer 19

1 - chronic heart failure
4 - renal and/or liver failure

• BOTH can cause fluid overload

Question 20

Which of the following is NOT an adverse effect of loop diuretics?

1 - hypotension
2 - low electrolyte state
3 - hyponatraemia
4 - hearing loss/tinnitus
5 - cardiac arrhythmias

Answer 20

5 - cardiac arrhythmias

• hypotension and low electrolyte state due to excretion
• hyponatraemia is most common, but if too much water is lost it can lead to hypernatraemia

Question 21

Loop diuretics, Bumetanide and Furosemide are contradicted in which 2 of the following:

1 - severe hypovolemia
2 - severe dehydration
3 - peripheral oedema
4 - nephrotic syndrome

Answer 21

1 - severe hypovolemia
2 - severe dehydration

Question 22

Loop diuretics, Bumetanide and Furosemide should be used with caution with all of the following except?

1 - hypokalaemia
2 - hyponatraemia
3 - glaucoma
4 - hepatic encephalopathy

Answer 22

3 - glaucoma

• low K+ can worsen hepatic encephalopathy and induce a coma

Question 23

Patients with gout should avoid the chronic use of loop diuretics, Bumetanide and Furosemide, why?

1 - K+ inhibits uric acid formation
2 - K+ inhibits crystal formation
3 - low H2O increases concentration of uric acid
4 - increased uric acid reabsorption

Answer 23

4 - increased uric acid reabsorption
- low circulating fluids can increase uric acid re-absorption in proximal tubules
- hypovolaemic patients can therefore have gout attacks due to increased uric acid re- absorption

Question 24

Can loop diuretics, Bumetanide and Furosemide, increase or decrease lithium levels?

Answer 24

• increases
• due to reduced excretion

Question 25

Can loop diuretics, Bumetanide and Furosemide, increase or decrease the risk of toxicity of digoxin?

Answer 25

- increase risk of toxicity - less is filtered out of the kidneys

Question 26

Loop diuretics, Bumetanide and Furosemide, can increase ototoxicity and nephrotoxitiy of which drug due to lower excretion levels? 1 - Gentamicin 2 - Co-Amoxiclav 3 - Amlodipine 4 - Spironolactone

Answer 26

1 - Gentamicin - common side effect of this drug, so if it is not being excreted then more will increase the risk of side effects

Question 27

What is the most important to monitor in patients who are prescribed loop diuretics, Bumetanide and Furosemide? 1 - U&Es 2 - FBC 3 - eGFR 4 - LFTs

Answer 27

1 - U&Es - important to monitor Na+, K+, Cl-, Ca2+ and Mg2+ levels