Filtration Fraction

\[FF=\frac{GFR}{RPF}\]

Variables

FFfiltration fraction

GFRglomerular filtration rate (mL/min)

RPFrenal plasma flow (mL/min)

Description

What is this formula?

The Filtration Fraction (FF) represents the proportion of renal plasma flow that is filtered through the glomeruli to form the initial filtrate.

When to use it

Use this formula when evaluating renal hemodynamics, glomerular function, renal perfusion, or physiological kidney function.

Example

Data:

GFR = 120 mL/min

RPF = 600 mL/min

Formula:

FF = GFR / RPF

Substitution:

FF = 120 / 600

Result:

FF = 0.20

FF = 20%

Approximately 20% of the plasma entering the kidneys is filtered by the glomeruli.

Applications

- Renal physiology

- Nephrology

- Kidney hemodynamic studies

- Renal perfusion assessment

- Research and education

Note

Filtration fraction is a physiological ratio and may vary according to changes in glomerular pressure, renal blood flow, and vascular resistance. Normal values are typically around 20%. Abnormal values may be observed in conditions affecting renal hemodynamics, including dehydration, heart failure, and certain renal diseases.