Diuretics And UTIs

Question 1

What is a diuretic?

Answer 1

A substance that acts upon the kidney to increase the production of urine and eliminate water from the body.

Question 2

What are diuretics commonly used for?

Answer 2

Reducing plasma volume and blood pressure,
Reducing oedema/ascites,
Treatment of congestive heart failure.

Question 3

What are the 5 main classes of diuretic?

Answer 3

Carbonic anhydrase diuretics,
Osmotic diuretics,
Loop diuretics,
Potassium sparing diuretics,
Thiazide and thiazide like diuretics.

Question 4

How do carbonic anhydrase inhibitors work?

Answer 4

Inhibit carbonic anhydrase, reducing the sodium reabsorption that would occur alongside bicarbonate. As such, water remains within the nephron.

Question 5

What are flozins?

Answer 5

SGLT-2 inhibitors acting on the PCT to reduce sodium absorption. Used in treating diabetic nephropathy.

Question 6

How do osmotic diuretics work?

What is the downside of this?

Answer 6

Increase water excretion idependant to sodium by exhibiting an osmotic effect on the nephron lumen.
Expand the extracellular fluid volume before acting as a diuretic.

Question 7

Give an example of an osmotic diuretic.

When is it used?

Answer 7

Mannitol - given via IV.

Acute drug poisoning or to lower intraocular pressure before surgery.

Question 8

What are the side effects of osmotic diuretics?

Answer 8

Headache, nausea, volume expansion, complications of heart failure and pulmonary oedema, hypernatraemia.

Question 9

How do loop diuretics work?

Answer 9

Inhibit the NKCC2 symporter in the ascending limb of loop of henle, reducing ion intake. Also reduce absorption of magnesium and calcium as the nephron is not made as positive as it would be normally.

Question 10

Give two examples of loop diuretics.

When are these used?

Answer 10

Bumetanide, Furosemide.
Used first line for congestive heart failure and nephrotic syndrome. Also indicated in hypercalcaemia, acute hyperkalaemia and pulmonary oedema.

Question 11

What side effects (other than electrolyte imbalance and hypovolaemia) are common in loop diuretics?

Answer 11

Metabolic alkalosis, postural hypotension.

Question 12

How do thiazide diuretics work?

Answer 12

Block the sodium chloride cotransporter in the DCT. Sodium calcium antiporter therefore becomes favoured and causes reabsorption of more calcium.

Question 13

When are thiazides used?

Give an example of a thiazide.

Answer 13

First line antihypertensives.

Indapamide, bendroflumethiazide.

Question 14

What electrolyte imbalance can thiazides be used to treat?

Answer 14

Hypocalcaemia used in osteoporosis

Question 15

How do aldosterone antagonists work?

Name an aldosterone antagonist.

Answer 15

Inhibit aldosterone and as such the expression of ENAC and ROMK in the collecting duct.
Spironolactone.

Question 16

How do potassium sparing diuretics work?

Name a potassium sparing diuretic.

Answer 16

Block ENAC channels, causing slowing of the sodium potassium ATPase.
Amiloride.

Question 17

What may potassium sparing and aldosterone antagonist diuretics be used for?

Answer 17

Secondary hyperaldosteronism,
Nephrotic syndrome,
Cirrhosis.

Question 18

When are potassium sparing or aldosterone antagonists contraindicated?

Answer 18

Hyperkalaemia,

Liver disease.

Question 19

What is a lower UTI called?

What is an upper UTI called?

Answer 19

Acute cystitis,

Acute pyelonephritis.

Question 20

What barriers to UTI are there?

Answer 20

Emptying of the bladder,
Acidity of urine,
Mucosal barriers and IgA.

Question 21

Why are UTI more common in women?

Answer 21

Shorter urethra that is close to both vagina and anus, which house bacteria.

Question 22

What is the most common causative agent of UTI?

Why?

Answer 22

Ecoli,
Flagella allow movement through the urinary tract,
Pilli allow it to attach to the mucosal surfaces,
Haemolysin toxins damage host membranes and cause renal damage.

Question 23

What are common symptoms of acute cystitis?

Answer 23

Dysuria,
Cloudy urine,
Urgency and nocturia,
suprapubic tenderness.

Question 24

What symptoms are common in pyelonephritis?

Answer 24

High fever and rigors,
Loin pain and tenderness.
Nausea and vomiting,
Cystitis symptoms.

Question 25

How is an uncomplicated UTI determined?

Answer 25

Usual causative organism, normal urinary tract, normal urinary function.

Question 26

When might a UTI be complicated?

Answer 26

Virulent organism eg staph aureus,
Immune suppression,
Impaired renal function,
Pyelonephritis,
often in men.

Question 27

How should a urine sample be taken?

Answer 27

Mid stream, clean catch. Women should hold labia apart.

Question 28

What positive dipstick tests indicate infection?

Which causative organism may be an exception to this?

Answer 28

Nitrites and leucocytes.

Staphylococcus saprophyticus is negative for nitrites.

Question 29

When is imaging used in UTI?

Answer 29

Always in children,
Sepsis,
Pyelonephritis and renal involvement.

Question 30

How are UTIs treated?

Answer 30

Increased fluid intake,
Regular analgesia,
Trimethoprim 3 day course if uncomplicated. 5-7 if complicated.

Question 31

Which antibiotics may be used for cystitis?

Answer 31

Nitrofuantoin, trimethoprim, pivmecillinam, fosfomycin.

Question 32

How does pyelonephritis treatment differ to that of acute cystitis?

Answer 32

7-10 day course of coamoxiclav, ciprofloxacin or gentamicin (IV only, nephrotoxic).