Diuretics and Renal Replacement Therapy Flashcards Preview

Urinary System > Diuretics and Renal Replacement Therapy > Flashcards

Flashcards in Diuretics and Renal Replacement Therapy Deck (65)
Loading flashcards...
1

What is a diuretic?

A substance/drug that promotes diuresis
(Increased renal excretion)

2

What percentage is the normal fractional excretion of Na+?

Less than or equal to 1%

3

Aldosterone increases the expression of which channels/transporters?

Na/K/ATPase
ENaC
K+ channels

4

How do loop diuretics work and give an example?

Act on the loop of Henle
Block NKCC2 cotransporter
Eg. Furosemide

5

How do thiazides work and give an example?

Act on early DCT
Block NaCl cotransporter
Eg. Metolazone

6

How do K+ sparing diuretics work and give an example?

Act on late DCT and CD
Block ENaC channels
Eg. Amiloride

7

How do aldosterone antagonists work and give an example?

Eg. Spironolactone
Competitive inhibition of aldosterone on principle cells in late DT and CD

8

How does mannitol work?

Use small molecules to increase osmolarity of filtrate
Increased water excretion (decreased water reabsorption)

9

How are carbonic anhydrase inhibitors used as a diuretic?

Prevents uptake of bicarbonate as it cannot from water and CO2 to enter the cells
However can lead to metabolic acidosis due to all the bicarbonate in the urine

10

How do loop diuretics affect magnesium and calcium?

Magnesium and calcium reabsorption rely on the gradient of the thick ascending limb LOH
Therefore loop diuretics inhibit their reabsorption
Increased loss of calcium and magnesium
Can cause hypocalcaemia and hypomagnesiumia

11

Why are loop diuretics chosen to help heart failure failure and acute pulmonary oedema?

They are very potent diuretics

12

What can we use loop diuretics to treat?

Heart failure
Pulmonary oedema
Nephrotic syndrome
Renal failure
Liver cirrhosis
Hypercalcaemia

13

Why are thiazides good diuretics for the elderly?

Blocking Na+ reabsorption increases the Ca2+ reabsorption
Good for the elderly who are prone to osteoporosis

14

Why are thiazides ineffective in renal failure?

Less potent as only 5% sodium reabsorption inhibited

15

What are thiazides widely used for and why?

Hypertension
Decreased effective circulating volume and cause vasodilation

16

What is the potential problem when using thiazides?

Hypokalaemia

17

Why are K+ sparing diuretics often a bad choice?

Mild diuretics therefore cannot cope with large volume increases
Can produce severe hyperkalaemia esp if used in conjunction with ACEi, K+ supplements or in pts with renal failure

18

What is the preferred drug to treat ascites and oedema in cirrhosis?

Spironolactone

19

Which diuretics are often used in conjunction for heart failure?

Spironolactone
Loop diuretics

20

Why do we have to be careful when using diuretics?

Decreased circulatory volume and reduce perfusion pressure to the kidneys
This can activate RAAS
Causes water retention (counter productive)

21

Describe nephrotic syndrome

Increase in glomerular BM permeability to proteins
Proteinuria
Low plasma albumin - decreased oncotic pressure - oedema

22

What is ascites?

Free fluid in the peritoneal cavity

23

Describe hepatic encephalopathy

Reversible syndrome of impaired brain function
Occurs in cirrhosis with advanced liver failure
Causes confusion and comas
Signs - constructional apraxia (cannot draw a 5 pointed star) and flapping tremors
Includes elevated ammonia levels in blood
Hypokalaemia can cause this

24

Name some adverse effects of diuretics

Potassium abnormalities
Decreased blood volume - postural hypotension, dehydration
Increased uric acid levels - gout
Glucose intolerance
Raised LDLs
Erectile dysfunction (thiazides)
Gynaecomastia (spironolactone)

25

How can alcohol affect blood volume levels?

Inhibits ADH release

26

How does coffee affect the kidney?

Increases GFR
Decreased Na+ reabsorption
Increased loss of Na+ and water
Diuresis

27

Define end stage renal failure (ESRF)

When death is likely without renal replacement therapy
eGFR < 15 ml/min

28

Give some symptoms/signs of ESRF

Tiredness - overwhelming fatigue physically and mentally
Difficulty sleeping
Difficulty concentrating
Volume overload - oedema, SoB
Nausea/vomiting/reduced appetite
Restless legs/cramps
Pruritus (itchy)
Sexual dysfunction/reduced fertility
Increased infections

29

What percentage of patients with CKD are hypertensive?

80-85%

30

If you have no ADH, how much urine could be produced a day?

30 L/day