Lust 4

Question 1

Clearance

Answer 1

• Flow of plasma to remove a substance
• C_x=U_xV/P_x
  
  • _​= Volume/Time
  • ml/min or L/day
• V=Urine flow
• Ux=urine concentration of X
• Px=Plasma concentration of X
• Cx=Clearance of X

Question 2

Renal Blood Flow (RBF)

Answer 2

• 1200-1300ml/min
  
  • both kidneys
  • =20-25% of CO

Question 3

Renal Plasma Flow (RPF)

Answer 3

• PAH Clearance
• =RBF (1-hematocrit)
• 600-700 ml/min
  
  • both kidneys

Question 4

Glomerular Filtration Rate (GFR)

Answer 4

• Inulin Clearance
• 120-140 ml/min
• both kidneys

Question 5

Urine Production Rate

Answer 5

• 1ml/min
  
  • both kidneys
• range 0.4 to 20 ml/min

Question 6

Filtration Fraction (FF)

Answer 6

• GFR/RPF=125/660=20%

Question 7

PAH clearance

Answer 7

• para-amino hippuric acid(PAH)=Renal Plasma Flow
  
  • filtered and secreted by kidney

Question 8

Inulin Clearance

Answer 8

• Inulin Clearance=GFR
• Inulin
  
  • Only filtered
  • not
    
    • reabsorbed
    • broken down
    • secreted

Question 9

Creatinine Clearance

Answer 9

• used to assess GFR
  
  • plasma creatinine is inversely proptional to GFR
    
    • Doubling Plasma C= 50% GFR
    • 2mg Creatinine= 50% GFR
    • 4mg Creatinine=25% GFR
• endogenous product=naturally found in our body
• test requires measurement of:
  
  • blood creatinine
  • urine creatinine
  • 24 hr urine volume
• Amout of filtered creatinine at glomerulus= total amount in urine

Question 10

Decreased creatinine clearance indicates:

Answer 10

• decreased GFR
• impaired renal fxn

Question 11

Renal Handling of solutes

Answer 11

• Clearance=excretion rate
• Inulin=filtration rate

Question 13

Free Water Clearance

Answer 13

• amount of water added to or removed from an isotonic solution
  
  • result in urine osmolarity
• • Free water clearance=Dilute urine
    
    • Overhydrated
    • Diuretic
    • Alcohol
    • Caffeine
• • Free Water Clearance=Concentrated urine
    
    • Dehydrated
• Estimated from comparing urine osmolarity to plasma osmolarity
  
  • Urine/Plasma
  • U/P ratio