(07-02) - Clearance

Question 1

clearance - how much of a substance is eliminated from blood by secretion from kidneys

first thing - trying to measure how much filtrate is being produced

should be able to measure GFR - they actually do that in practice

clearnace can be of anything that’s in the blood

collect urine sample and blood sample and determine clearance

Question 2

define clearance

Answer 2

Question 3

(clinical importance)

1. key clinical measures of kindey function are measured using what?
2. What is the most common means of identifying kidney disease?
3. Chronic kidney disease is staged on the basis of GFR - as estimated by what?
4. Renal clearance is used as a guide to dosing drugs excreted by the kidneys.
5. the only way the kidneys get rid of creatinine is by filtratition (i think so anyway…)

Answer 3

1. clearance techniques
2. reduction of renal clearance
3. creatinine (GFR proportional to 1/SCr)

Question 4

measure this by measuring serum creatinine

dogs and cats vary too much structurally to do these types of measurements

there will be more creatinine for more muscle mass

Answer 4

these things disrupt measurements

Question 5

creatinine being used to stage kidney disease

breeds change a lot

so the most we can get out of it is whether or not it is stable or whether it is changing relative tot he same dog

Question 6

(Key points)

1. what is clearance?
2. what is renal clearance?

Answer 6

1. the rate at which a substance is removed from the body (any route)
2. reflects the ability of the kidneys to remove a substance from blood and excrete it in the final urine

Question 7

Answer 7

C

Question 8

(VAriation in renal clearance)

1. can renal clearance be calculated fro any substance?
2. May vary from what to what depending on how the substance is handled by the kidneys?
3. Under what circumstances would renal clearance occur?

Answer 8

1. yes
2. 0 to over 600 mL/min
3. have to secrete it out (filtration will only get rid of a subset)

Question 9

(Renal Clearance)

(Clearance units: volume per time)

1. not amount per time
2. typically expressed as mL/min or mL/min/kg or m^2

(Concepts)

1. the amount excreted must be contained in what?
2. the amount excreted must have been contained in what?
3. that volume of plasma has been what?

Answer 9

1. some volume of urine
2. some volume of plasma
3. “cleared”

Question 10

(GFR measured as clearance)

1. glomerular has same or different composition as plasma?
2. filtrate is concentrated or diluted as it is converted to urine?
3. Amount of filtrate produced (volume in ml/min) can be calculated by doing what?

Answer 10

1. same
2. concentrated
3. converting final urine into the volume of filtrate it generated from

Question 11

Answer 11

Question 12

(Clearance)

1. the kidney eliminates unwanted substances from what?
2. Think of clerance as the amount of blood or plasma that has been what?

Answer 12

1. the blood (and broadly, the ECF)
2. been completely cleared of a substance

Question 13

(Contrast with “filtered load”)

1. what is the “filtered load”?
2. GFR X Plasma concentration of substance

varies with what 2 things?

3. The filtered load represents what?

Answer 13

1. The amount of substance filtered into Bowman’s space per unit time (an amount, not a volume)
2. GFR an plasma concentration
3. the amount presented to the remainder of the nephron to process

Question 14

Answer 14

A

Question 15

Answer 15

B

Question 16