Clearance FEna

Question 1

How do we calculate input of a substance entering the kidney?

Answer 1

Concentration of that substance multiplied by the renal arterial plasma flow.

Question 2

How do you calculate output of a substance from the kidney? Remember two parts here.

Answer 2

There are two outputs. Renal vein and ureter.

1. Renal vein concentration x Renal venous plasma flow
2. Urine concentration of the substance x urine flow

Question 3

Equation for clearance?

Answer 3

Urinary excretion rate/plasma contraction

Question 4

So, what is an easy way to calculate GFR?

Answer 4

Clearance of insulin equals the GFR

Question 5

How do you solve for renal plasma flow?

Answer 5

PAH clearance/PAH extraction ratio (usually .9)

Question 6

How do we calculate the Extraction Ratio of PAH?

Answer 6

Arterial PAH-Venous PAH/Arterail PAH

Question 7

How do you calculate Renal Blood Flow from the Renal Plasma Flow?

Answer 7

RPF/1-HCT

Question 8

What is the equation for filtered load?

Answer 8

GFR * Pc

Question 9

What is excreted load?

Answer 9

Uc * Urine flow rate

Question 10

Equation for filtration fraction?

Answer 10

GFR/RPF

Question 11

What is the equation for FeNa?

Answer 11

Excretion/filtered

Question 12

What happens with pre renal acute kidney injury to Fena and BUN Cr ratio?

Answer 12

Fena goes down to less than 1 and BUN/Cr goes up.

Question 13

What happens to Fena and Bun/Cr during intrarenal injury?

Answer 13

Fena goes up. Bun goes down.