9. Oedema

Question 1

Diuretics counselling

Answer 1

Diuretics should be taken in the morning, to prevent it from disturbing sleep at night

Question 2

Diuretics list

Answer 2

Loop
Bumetanide
Furosemide
Torasemide

Thiazides diuretics
* Bendroflumethiazide
* Hydrochlorothiazide

Thiazide- related diuretics
* Chlortalidone
* Indapimide

Typically used in place of or adjunct to loop and thiazide diuretics:

Aldosterone antagonist
* Spiranolactone
* Eplerenone

Potassium-sparing
* Amiloride
* Triamtrene (blue urine)

Typically used in glaucoma, cerebral oedema:
* Osmotic
mannitol
* Carbonic anyhydrase inhibitors
Brinzolamide
Dorzolamide

Question 3

Diuretics mechanism of action

Answer 3

Causes the kidneys to make more urine, by preventing sodium from being reabsopred into the blood

More sodium is excreted and therefore more water is excreted.

Different diuretics target different parts of the nephron

Question 4

Risk with diuretics

Answer 4

Excess doses may cause excessive water to be lost = plasma volume depletes = low blood pressure

Question 5

Kidney sick day rules

Answer 5

Kidney sick day rules
Diuretics reduce blood flow to the kidneys, as fluid is lost, therefore GFR is reduced. You are more likely to be dehydrated when you are ill, therefore increasing the risk for an AKI.

Some drugs need to be stopped during an intercurrent illness such as diarrhoea, vomiting, fever as there is a higher risk of acute kidney injury

Therefore diuretics will have to be stopped when you are ill

Question 6

Loop diuretics caution

Answer 6

Loop diuretics cause high glucose levels and high uric acid levels. This may exacerbate diabetes and gout

Question 7

Loop diuretics side effect

Answer 7

• Ototoxicity –> tinnitus –> deafness
• Acute urinary retention
  Caution in patents with an enlarged prostate as this condition is already characterised with urinary retention
• Electrolyte imbalances
  e.g hyponatraemia,
  e.g hypokalaemia –> arrhythmias, severe in patients who have severe cardiovascular disease, Also in patients who are taking digoxin, as hypokalaemia predisposes to digoxin toxicity

hyperkalaemia can precipitate hepatic encephalopathy in patients with renal impairement

Question 8

Loop diuretics interaction

Answer 8

• Interacts with drugs that ALSO cause ototoxicity:
  Aminoglycosides e.g gentamicin, therefore seperate doses by long periods
• Interacts with drugs that ALSO cause nephrotoxicty
  Aminoglycosides e.g gentamicin, take caution

Question 9

Thiazide & related diuretics

Answer 9

Block Na/Cl transporter on proximal distal convoluted tubule

They take 1-2 hours to work and their effects last 12-24 hours

Question 10

Thiazide & related diuretics caution

Answer 10

Also causes an increase in uric acid and glucose levels, therefore used with caution in diabetes and gout
(Indapimide is least likely to cause an increase in glucose, out of all thiazide diuretics).

Question 11

Thiazide & related diuretics and renal impairment
(including the exceptions)

Answer 11

Thiazide & related diuretics are ineffective in severe renal impairement.
Except: metolazone

Question 12

Thiazide & related diuretics side effects

Answer 12

• Electrolyte imbalances
  Can cause also hypercalcaemia
• Gastro-intestinal disturbance
• Impotence
• Skin-reactions: hydochlorothiazide may cause non-melanoma skin cancer via long term use
  Patients must report new or changed skin lesions. They must limit sun and UV exposure and use adequate sun protection.
• Can cause high LDL cholesterol and triglycerides

Question 13

Thiazide & related diuretics interactions

Answer 13

• Interacts with drugs that ALSO cause hypotension
  ACE inhibitors/ARB’s, alpha-blockers, beta-blockers, calcium-channnel blockers, antidepressant, Anti-parkinsonian drug, Antipsychotic, nitrates, phosphodiesterase-type 5 inhibitor e.g sildenafil, SGLT2 inhibitore.g canaglifozin
• Interacts with drugs that also cause hypOkalaemia - this predisposes to digoxin toxicty
  Beta2 agonists, corticosteroids, theophylline
• Hypokalaemia and drugs that prolong the QT interval have an increased combined risk for torsade de pointes
  Drugs which prolong QT interval: anti-arrhythmic drugs, anti-psychotics, clomipramine, clarithromycin, erythromycin, citalopram, escitalopram
• Interacts with drugs that cause also hypONatraemia
  Antidepressants, carbamazepine, desmopressin, concomitat diuretic, NSAID (which also may precipitate AKI if taken with thiazide & related diuretics)

HypoNatraemia also predisposes to lithium toxicity

Question 14

Potassium-sparing diuretics

Answer 14

Block Na+ channels in the late distal convoluted tubule

Question 15

Aldosterone antagonists mechanism of action

Answer 15

A type of potassium sparing diuretic. Block aldosterone, which acts on Na+ channels on the late distal convoluted tubule

Question 16

Potassium-sparing diuretics side effects

Answer 16

• HypERkalaemia
• HypONatraemia

Urine may look slightly blue in patients taking triamterene

HypONatraemia is a typical side effect of diuretics, as when Na transporter is mostly blocked

Question 17

Potassium-sparing diuretics interactions

Answer 17

• Interacts with drugs that cause also hypONatraemia
  Antidepressants, carbamazepine, desmopressin, concomitat diuretic, NSAID (which also may precipitate AKI if taken with thiazide & related diuretics)

HypoNatraemia also predisposes to lithium toxicity

• Interacts with drugs that cause HypERkalaemia
  Ace inhibitors/ARB, aldosterone antagonist, heparin, NSAID, Potassium supplement, trimethoprim

Question 18

Aldosterone antagonists side effects

Answer 18

• HypERkalaemia
• HypONatraemia
• Gynaecomastia, libido changes, menstrual disturbances (specific to spiranolactone)
  Benign breast tumours, hypertrichosis

Hyperkalaemia in liver impairement can lead to encephalopathy

Question 19

Aldosterone antagonists interactions

Answer 19

• Interacts with drugs that cause HypERkalaemia
  Ace inhibitors/ARB, aldosterone antagonist, heparin, NSAID, Potassium supplement, trimethoprim