Session 7 - Diuretics Flashcards Preview

Semester 3 - Urinary > Session 7 - Diuretics > Flashcards

Flashcards in Session 7 - Diuretics Deck (36):
1

Define diuresis

• Increased formation of urine by the kidney

2

Define diuretics

• Block reabsorption of Na+ and therefore water by the kidney

3

Give three main types of diuretics

• Loop diuretics
• Thiazide diuretics
• K+ sparing diuretics and aldosterone antagonists

4

How do loop diuretics work?

• Acts on TAL of the loop of henle
• Block Na-K-2Cl
• Causes excretion of 10-25% of filtered Na+ ions (segments downstream also have limited capacity to reabsorb water, increasing diuresis)

5

Name two loop diuretics

• Furosemide
• Bumetanide

6

What do Thiazide diuretics do?

• Act on early DCT
• Block Na-Cl co-transporter
• Inhibits only 5% of Na+ reabsorption

7

Give a thiazide diuretic

• Bendroflumethiazide

8

Where do K+ sparing diuretics and aldosterone antagonists work?

• Late DCT and collecting duct
• Reduce ENaC reabsorption of sodium
• Inhibit 2% Na+ reabsorption

9

Why are K+ sparing diuretics named thus?

Reduce the loss of K+ and can produce life threatening hyperkalaemia

10

Give an example of a K+ sparing diuretic

• Amiloride

11

Give an example of an aldosterone antagonist

• Spironolactone

12

Give overall dangers of diuretics

• Hyper/hypokalaemia
• RAAS activation

13

Outline the negatives of using K+ sparing diuretics/Aldosterone Antagonists

• Reduce loss of K+ and may produce life threatening hyperkalaemia

14

Give a negative effect of loop diuretics

• Reduces calcium absorption, inducing urinary excretion

Patient may become hypocalcaemi

15

What do loop and thiazide diuretics do?

• Increase the loss of potassium in the urine

Hypokalaemia

16

Outline how loop and thiazide diuretics cause hypokalaemia

• Block Na+ and H20 reabsorption in LoH or early DCT
• Increase Na+ and H20 delivery to late DT + CD
• Increase Na+ absorption by principle cells/Faster flow rate of filtrate so K+ washed away faster
• Favourable electrical gradient for K+ excretion/Low K+ concentration in lumen

17

How do K+ sparing diuretics cause hyperkalaemia?

• Block epithelial Na+ channels
• Reduce Na+ reabsorption
• Reduce potassium loss in urine
• Hyperkalaemia

18

How do aldosterone antagonists cause hyperkalaemia?

• Block of action of aldosterone
• Reduce activity of Na/K+ ATPase & epithelial Na+ channels
• Reduce Na+ reabsorption
• Reduce potassium loss in urine
• Hyperkalaemia

19

What do all diuretics do?

• Reduce ECF volume so activate RAAS
• This increases aldosterone secretion, increase Na+ reabsorption and K+ secretion, contributing to hypokalaemia

20

List negative effects which come about as a result of diuretics use and abuse

• Hypokalaemia
• Hyperkalaemia
• RAAS activation
• Hypovolaemia
• Hyponatraemia
• Increased uric acid levels in blood
• Metabolic effects

21

What is hypovolaemia?

• Decreased ECF volume due to excessive loss of Na+ and water

22

What 3 things must be done to avoid hypovolaemia?

• Monitor weight
• Look for signs of dehydration
• Check BP

23

What is hyponatraemia?

• Decreased sodium in blood

Multiple symptoms, including nausea, vomiting, headache and confusion

24

What do increased uric acid levels in blood cause?

Gout

25

What are two negative metabolic effect of diuretic use?

• Glucose intolerance
• Increased LDL levels

26

What is a carbonic anhydrase inhibitor?

• Diuretic which acts in PCT by inhibitng enzyme carbonic anhydrase to interfere with Na+ and HCO3- reabsorption

27

Why is carbonic anhydrase no longer used a diuretic?

• HCO3- loss leads to metabolic acidosis

28

Give six conditions diuretics used to treat

• Conditions with ECF expansion and Oedema
• Acute pulmonary oedema
• Hypertension
• Hypercalcaemia
• Cerebral oedema (Osmotic diuretics)
• Glaucoma (carbonic anydrase)

29

Give four conditions which involve ECF expansion and oedema

• Congestive heart failure
• Nephrotic syndrome
• Kidney failure
• Ascites and oedema due to liver cirrhosis

30

What is acute pulmonary oedema usually due to?

• Left heart failure

31

What is pulmonary oedema treated with?

• Loop diuretics

32

What is hypertension treated with?

• Thiazide diuretics
• Spironolactone in primary hyperaldosteronism (Conn's syndrome)

33

How is hypercalcaemia treated?

• Loop diuretics promote Ca2+ excretion in loop of henle

34

Give three substances with diuretic actions

• Alcohol - Inhibits ADH release
• Coffee - Increased GFR, decreased Na+ reabsorption
• Lithium - Inhibits ADH action on collection ducts

35

What is diuresis expressed as in the form of a symptom?

• Polyuria

36

Give four causes of polyuria that are non drink related

• Diabetes mellitus
○ Glucose in filtrate -> Osmotic diuresis
• Central diabetes insipidus
○ Decreased ADH release from posterior pituitary -> Diuresis
• Nephrogenic diabetes insipidus
○ Poor response of collecting ducts to ADH -> Diuresis
• Psychogenic polydypsia
○ Increased intake of fluid