# Clearance FEna Flashcards

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

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

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

There are two outputs. Renal vein and ureter.

- Renal vein concentration x Renal venous plasma flow
- Urine concentration of the substance x urine flow

Equation for clearance?

Urinary excretion rate/plasma contraction

So, what is an easy way to calculate GFR?

Clearance of insulin equals the GFR

How do you solve for renal plasma flow?

PAH clearance/PAH extraction ratio (usually .9)

How do we calculate the Extraction Ratio of PAH?

Arterial PAH-Venous PAH/Arterail PAH

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

RPF/1-HCT

What is the equation for filtered load?

GFR * Pc

What is excreted load?

Uc * Urine flow rate

Equation for filtration fraction?

GFR/RPF

What is the equation for FeNa?

Excretion/filtered

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

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

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

Fena goes up. Bun goes down.