Renal

Question 1

What does vasopressin do?

Answer 1

Vasopressin (ADH) is released from the poster pituitary gland. It increases number of water channels in collecting ducts, allowing the positive reabsorbtion of water.

In cranial diabetes insipidus, absence of ADH causes excretion of large volumes of hypotonic urine

Question 2

What are diuretics?

Answer 2

Increase the production of urine by the kidneys. The decrease the reabsorption of water + electrolytes in the renal tubules = increased flow of urine + increased sodium loss.

Question 3

What are the causes of sodium + water retention?

Answer 3

-low cardiac output e.g. in heart failure results in under filling of
arterial System = kidneys to excrete less sodium + water
-raised pressure in veins + capillaries = fluid movement from blood to
tissue spaces
-low protein in plasma e.g. due to liver cirrhosis
-increased secretion of aldosterone by adrenal glands
-excessive activity of SNS + RAAS

Question 4

What are osmotic diuretics?

Answer 4

E.g.mannitol
-substances pass through the glomeruli + are NOT reabsorbed by
the renal tubules = increases osmotic pressure of filtrate
-not used in heart failure because they increase blood volume
-used in cerebral oedema + reduce ICP

Question 5

What are thiazide diuretics?

Answer 5

E.g. metolazone, bendroflumethiazide
-decrease sodium reabsorption by inhibiting action of Na+/Cl-
pump In the distal convoluted tubule (DCT).
-increases potassium excretion -potassium supplements may be required to prevent hypokalaemia
-uses;
-cardiac failure
-hypertension

Side effects;
-weakness, impotence, skin rashes, allergic reactions
-hypokalaemia - can precipitate cardiac arrhythmias
-hyperuricaemia - uric acid levels in blood are increased
-impaired glucose intolerance (contraindicated in pts with non-insulin
dependent diabetes)
-increased plasma cholesterol levels

Question 6

What are loop diuretics?

Answer 6

E.g. furosemide, bumetanide
-inhibit the Na+/K+/2Cl- cotransporter in the ascending loop of
Henle
-venodilatiom reduces preload in acute LVF

Question 7

What are the different stages of heart failure?

Answer 7

NYHA classification

Class I - NO symptoms or limitation in ordinary physical exercise

Class II- MILD symptoms (slight SOB) + slight limitation during ordinary
activity

Class III- MARKED limitation in activities. Comfortable only at rest

Class IV- SEVERE limitations. Experience symptoms even at rest. Mostly
bedbound pts.

Question 8

What are potassium sparing diuretics?

Answer 8

E.g. amiloride, triamterene, spironolactone (aldosterone antagonist)
-work in distal tubule + collecting ducts + inhibit sodium
reabsorbtion + potassium excretion

ACEi + ARBs also inhibit aldosterone + so are weak potassium sparing diuretics

Question 9

How is the extent of renal failure calculated?

Answer 9

Ratio between pts creatine clearance + ideal creatine clearance

Question 10

What phase of pharmacokinetics of a drug can be altered by renal failure?

Answer 10

All; absorption, metabolism, distribution + excretion

Question 11

What drugs can cause acute kidney injury?

Answer 11

Statins, antihypertensives, diagnostic agents + antibiotics

Question 12

Can diuretics be prescribed to treat AKI?

Answer 12

No they are contraindicated, they can cause AKI

Question 13

How is the glomerular filtration rate established?

Answer 13

Measuring blood creatine levels

Question 14

What describes stage 1 of acute kidney injury?

Answer 14

Stage 1

• urine output <0.5 mL/kg/h for 6-12h
• serum creatine 1.5-1.9 x baseline

Stage 2

• urine output <0.5 mL/kg/h for >12h
• serum creatine 2.0-2.9 x baseline

Stage 3

• urine output <0.3 mL/kg/h for 24h
• serum creatine >3 x baseline