GFR and CLEARANCE

Question 1

GFR is the clinical index

Answer 1

• of renal function

Question 2

clearance

Answer 2

• urine concentration x urine flow rate/ plasma concentration

Question 3

GOLD STANDARD FOR MEASURING GFR

Answer 3

• INULIN CLEARANCE
• FOR CLINICAL USE CREATININE concentration
• sucrose and mannitol

Question 4

CREATININE

Answer 4

• is released from the skeletal muscle at a constant rate proportional to muscle mass
• muscle mass decrease with age but GFR also normally decreases with age
• freely filtered but not reabsorbed by the kidney

Question 5

skeletal muscle injury

Answer 5

• increase release of CREATININE into the circulation

- is freely filter and NON IS REABSORBED

Question 6

INCREASE GFR

Answer 6

• filter more creatinine, more creatinine is excreted

- causing decrease in plasma level

Question 7

creatinine is INVERSE to

Answer 7

• GFR

Question 8

24 HOUR URINE SAMPLE

Answer 8

• clearance = urine conc of pH x urine flow/ plasma

Question 9

case of nephrotic syndrome:(non-inflammatory injury of the capillary membrane) normal surface area
ssx: pitting edema on LE
BP normal
creatinine = 0.89 mg/dl N
BUN = 13 mg/dl N
albumin = 1.6 g/dl LOW
calculated urine excretion of protein = 7.4 g/day INCREASEd
urine sediment occasional hyaline cast, red cells rare, oval fat bodies

Answer 9

BUN normal meaning normal GFR

albumin LOW source of pitting edema

Question 10

case of a nephritic syndrome: (has inflammatory injury to the glomerular membrane) lose surface area decreasing GFR
ssx: dark maroon urine
BP 148/107 due Na and water retention
creatinine = 2.6 mg/dl increase
BUN = 36 mg/dl increase
albumin = 4.1 g/dl
urinalysis small amount of protein, but many RBC

Answer 10

increase creatinine, will decrease GFR

BUN increase