Filtration fraction

Parameter	Value
renal blood flow	RBF = 1000 mL/min
hematocrit	HCT = 40%
glomerular filtration rate	GFR = 120 mL/min
renal plasma flow	RPF = 600 mL/min
filtration fraction	FF = 20%
urine flow rate	V = 1 mL/min

Sodium	Inulin	Creatinine	PAH
SNa= 150 mEq/L	SIn= 1 mg/mL	SCr= 0.01 mg/mL	SPAH=
UNa= 710 mEq/L	UIn= 150 mg/mL	UCr= 1.25 mg/mL	UPAH=
CNa= 5 mL/min	CIn= 150 mL/min	CCr= 125 mL/min	CPAH= 420 mL/min
			ER= 90%
			ERPF= 540 mL/min

In renal physiology, thefiltration fractionis the ratio of theglomerular filtration rate(GFR) over therenal plasma flow(RPF).

Filtration Fraction, FF = GFR/RPF, or$FF={\frac {GFR}{RPF}}$.

The filtration fraction, therefore, represents the proportion of the fluid reaching thekidneysthat passes into therenal tubules.It is normally about 20%.

GFR on its own is the most common and important measure ofrenal function.However, in conditions such asrenal artery stenosis,blood flowto the kidneys is reduced. Filtration fraction must therefore be increased in order to perform the normal functions of the kidney.Loop diureticsandthiazide diureticsdecrease filtration fraction.

Catecholamines(norepinephrineandepinephrine) increase filtration fraction byvasoconstrictionofafferentandefferent arterioles,possibly through activation ofAlpha -1 adrenergic receptors.

Severehemorrhagewill also result in an increased filtration fraction.