Renal Therapeutics 2: Kidney Disease Flashcards
What is acute kidney injury?
Rapid potential reversible decline in renal function occurring in hours
What is chronic kidney disease?
Slowly worsening loss of the ability of the kidneys to remove waste, concentrate urine and converse electrolytes.
Solved by transplant or dialysis
What is behind pre-renal cause and failure?
Decreased renal perfusion which leads to reduction in GFR
What is behind intrinsic renal cause and failure? (before the initial filtration and blood flow into the bowmans capsule)
Damage to nephrons
What is behind post-renal cause and failure?
Obstruction of urine flow
What are the causes of glomerular dysfunction?
- 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
What are the consequences of glomerular dysfunction?
- 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
What are the functions of tubules?
Selective reabsorption of water and electrolytes
What are the consequences of tubular failure?
- Polyuria (production of an abnormal large amount of volume of dilute urine)
- Alterations in electrolytes
What happens with a failure of the loop of henle?
- Urine cannot be concentrated as there’s a missing medulla gradient
- Has a knock on effect as a whole on the nephron
What happens with a proximal tubular failure?
Leads to K+ loss
What happens with distal tubular failure?
- 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
What are nephrotoxic drugs?
Drugs which affect the kidneys and its function negatively
Describe the acute kidney disease time course?
- Pre-renal cause (underlaying cause of the problem)
- GFR decreases and oliguria occurs (decrease in the amount of urea)
- Acute tubular necrosis
- Oliguric phase (less urine) this is due to glomerular + tubular dysfunction
- Polyuric Phase- glomeruli recovers- leads to persistent tubular dysfunction (filteration increases, but concentration mechanism doesn’t work)
- Recovery period if the pre-renal cause is solved, kidneys repair its tubules
What can the oliguric phase lead to?
- Fluid and electrolyte overload
- Accumulation of metabolites
- Infections bleeding
- All related to volume overload (hypertension, oedema)
What can the polyuric phase lead to?
- Dehydration (loss of too much water)
- Electrolyte depletion (Less problematic as there’s modern treatment- supplements)
- Volume depletion, nausea, vomiting, muscle cramps= loss of electrolytes
How do you manage acute kidney injury?
- Remove the cause
2. Keep the patient alive until kidney function has recovered through dialysis
How do you restore the function in pre-renal failure?
- Fluid or blood replenishment
- Restoration of cardiovascular function
- Prevent acute tubular necrosis
- Aggressive diuretic therapy to flush out the problem
How can you use Ca2+ channel blockers to restore function in kidneys?
- Dilate the pre-glomerular arterioles which increase the blood flow to the glomerulus which increases filtration
- Also induces natriuresis- excretion of sodium
How can you use diuretics to restore function in kidneys?
Group of drugs that block the normal solute reabsorption
What do the class of diuretics of thiazides do?
- Block Na+ and Cl- reabsorption in the distal tubule
- Leads to K+ excretion which leads to hypokalaemia
- First use to lower blood pressure in hypertension
- Used to reduce Ca2+ excretion and treatment of kidney stones
- Example: Benzothiazide
What do the class of diuretics of loop diuretics do?
- Block Cl-, Na+, K+ reabsorption in the loop of henle which leads to the side effect of K+ loss can lead to hypokalaemia
- Treatment of patient with volume overload
- Actively secreted in proximal tubule
- Side effects can also lead to increased Ca2+, Mg2+ excretion, hyperglycaemia and GI disturbances
- Indication: Oedema of the lung, Anuria, Poisoning (flush it out of the body of the toxic dose)
What do the class of diuretics called K+ sparing diuretics do?
- Block the Na+ and K+ exchange pump which leads to natriuresis
- Increases water excretion and decreased K+ excretion
- Can lead to hyperkalaemia
What do the class of diuretics called osmotic diuretic do?
- It’s glomerular filtered and blocks the water reabsorption in the whole of the nephron
- Leads to extracellular volume before producing diuresis
What is Hyperkalaemia?
- Increase in the concentration of potassium in the blood stream
- Can have some severe consequences, altering electrophysiology leading to cardiac arrhythmias
- Potassium levels can be managed through diet over the longer term
- Acute treatment with insulin or salbutamol causes a shift of potassium from the blood stream into the cells
