Renal Therapeutics 2: Kidney Disease

Question 1

What is acute kidney injury?

Answer 1

Rapid potential reversible decline in renal function occurring in hours

Question 2

What is chronic kidney disease?

Answer 2

Slowly worsening loss of the ability of the kidneys to remove waste, concentrate urine and converse electrolytes.

Solved by transplant or dialysis

Question 3

What is behind pre-renal cause and failure?

Answer 3

Decreased renal perfusion which leads to reduction in GFR

Question 4

What is behind intrinsic renal cause and failure? (before the initial filtration and blood flow into the bowmans capsule)

Answer 4

Damage to nephrons

Question 5

What is behind post-renal cause and failure?

Answer 5

Obstruction of urine flow

Question 6

What are the causes of glomerular dysfunction?

Answer 6

• Pre-renal perfusion (alteration to the blood flow to the glomerulus which reduces GFR)
• Intrinsic glomerular inflammation and post-renal obstruction
• Fall of GFR with retention of substances which are cleared by filtration- back into the blood stream to cause problems

Question 7

What are the consequences of glomerular dysfunction?

Answer 7

• Reduced volume, slower tubular flow, increased tubular reabsorption
• Less Na+ means less Na+ for distal exchange mechanism with K+ and acid- this leads to a knock on effect on the electrolytes that’ll effect the nephron
• May induce proteinuria which may induce protein loss in the urine

Question 8

What are the functions of tubules?

Answer 8

Selective reabsorption of water and electrolytes

Question 9

What are the consequences of tubular failure?

Answer 9

1. Polyuria (production of an abnormal large amount of volume of dilute urine)
2. Alterations in electrolytes

Question 10

What happens with a failure of the loop of henle?

Answer 10

1. Urine cannot be concentrated as there’s a missing medulla gradient
2. Has a knock on effect as a whole on the nephron

Question 11

What happens with a proximal tubular failure?

Answer 11

Leads to K+ loss

Question 12

What happens with distal tubular failure?

Answer 12

• Impaired Na+ K+ acid exchange pump, failed acid secretion leads to more H+ ions which leads to acidosis
• This can change the pH of the blood

Question 13

What are nephrotoxic drugs?

Answer 13

Drugs which affect the kidneys and its function negatively

Question 14

Describe the acute kidney disease time course?

Answer 14

1. Pre-renal cause (underlaying cause of the problem)
2. GFR decreases and oliguria occurs (decrease in the amount of urea)
3. Acute tubular necrosis
4. Oliguric phase (less urine) this is due to glomerular + tubular dysfunction
5. Polyuric Phase- glomeruli recovers- leads to persistent tubular dysfunction (filteration increases, but concentration mechanism doesn’t work)
6. Recovery period if the pre-renal cause is solved, kidneys repair its tubules

Question 15

What can the oliguric phase lead to?

Answer 15

1. Fluid and electrolyte overload
2. Accumulation of metabolites
3. Infections bleeding
   - All related to volume overload (hypertension, oedema)

Question 16

What can the polyuric phase lead to?

Answer 16

1. Dehydration (loss of too much water)
2. Electrolyte depletion (Less problematic as there’s modern treatment- supplements)
3. Volume depletion, nausea, vomiting, muscle cramps= loss of electrolytes

Question 17

How do you manage acute kidney injury?

Answer 17

1. Remove the cause

2. Keep the patient alive until kidney function has recovered through dialysis

Question 18

How do you restore the function in pre-renal failure?

Answer 18

1. Fluid or blood replenishment
2. Restoration of cardiovascular function
3. Prevent acute tubular necrosis
4. Aggressive diuretic therapy to flush out the problem

Question 19

How can you use Ca2+ channel blockers to restore function in kidneys?

Answer 19

1. Dilate the pre-glomerular arterioles which increase the blood flow to the glomerulus which increases filtration
2. Also induces natriuresis- excretion of sodium

Question 20

How can you use diuretics to restore function in kidneys?

Answer 20

Group of drugs that block the normal solute reabsorption

Question 21

What do the class of diuretics of thiazides do?

Answer 21

1. Block Na+ and Cl- reabsorption in the distal tubule
2. Leads to K+ excretion which leads to hypokalaemia
3. First use to lower blood pressure in hypertension
4. Used to reduce Ca2+ excretion and treatment of kidney stones
5. Example: Benzothiazide

Question 22

What do the class of diuretics of loop diuretics do?

Answer 22

1. Block Cl-, Na+, K+ reabsorption in the loop of henle which leads to the side effect of K+ loss can lead to hypokalaemia
2. Treatment of patient with volume overload
3. Actively secreted in proximal tubule
4. Side effects can also lead to increased Ca2+, Mg2+ excretion, hyperglycaemia and GI disturbances
5. Indication: Oedema of the lung, Anuria, Poisoning (flush it out of the body of the toxic dose)

Question 23

What do the class of diuretics called K+ sparing diuretics do?

Answer 23

1. Block the Na+ and K+ exchange pump which leads to natriuresis
2. Increases water excretion and decreased K+ excretion
3. Can lead to hyperkalaemia

Question 24

What do the class of diuretics called osmotic diuretic do?

Answer 24

1. It’s glomerular filtered and blocks the water reabsorption in the whole of the nephron
2. Leads to extracellular volume before producing diuresis

Question 25

What is Hyperkalaemia?

Answer 25

1. Increase in the concentration of potassium in the blood stream
2. Can have some severe consequences, altering electrophysiology leading to cardiac arrhythmias
3. Potassium levels can be managed through diet over the longer term
4. Acute treatment with insulin or salbutamol causes a shift of potassium from the blood stream into the cells