GFR Calculator

Determines the glomerular filtration rate based on serum creatinine, patient age, gender and race.

The GFR calculator estimates the glomerular filtration rate, which is an overall index of kidney function, both for adult and pediatric patients.

It offers results from three different equations and is based on serum creatinine levels in mg/dL, patient age, gender and race.

This calculator uses the following formulas (click on each of the links provided to jump to it):

■ The CKD-EPI formula;

Serum creatinine
Age
Gender
Race
Embed  Print  Share
Serum creatinine
Height
Print

Steps on how to print your input & results:

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.

Glomerular filtration rate explained

GFR is the most important of the parameters that evaluate kidney function. It is estimated through different methods based on serum creatinine.

Creatinine is the break down product of the creatinine phosphate, involved in muscular function. Serum creatinine levels determine the clearance that is used further on to establish GFR.

GFR offers information on the amount of liquid that gets filtered by the capillaries of the kidney glomerular into the Bowman's capsule during a specific time period.

Thus, its value shows how efficiently the kidneys perform their function, that of cleaning blood of different waste products and toxins and their excretion through urine.

Glomerular filtration rate can be physically determined by comparing concentrations of a marker substance in a sample of blood an in a sample of urine.

GFR formulas

The above calculator employs the following formulas to determine the glomerular filtration rate:

The IDMS-traceable MDRD equation:

GFR = 175 x (SCr)-1.154 x (Age)-0.203 x (0.742 only if female) x (1.212 only if black)

The CKD-EPI formula is composed based on patient gender and race, as presented in the following table:

 Race Gender Serum Creatinine (SCr) Formula (GFR = …) White/ Other race Female ≤0.7 144 x (SCr/0.7)-0.329 x 0.993Age >0.7 144 x (SCr/0.7)-1.209 x 0.993Age Male ≤0.9 141 x (SCr/0.9)-0.411 x 0.993Age >0.9 141 x (SCr/0.9)-1.209 x 0.993Age Black Female ≤0.7 166 x (SCr/0.7)-0.329 x 0.993Age >0.7 166 x (SCr/0.7)-1.209 x 0.993Age Male ≤0.9 163 x (SCr/0.9)-0.411 x 0.993Age >0.9 163 x (SCr/0.9)-1.209 x 0.993Age

GFR = e(1.911 + 5.249/SCr - 2.114/SCr2 - 0.00686 x Age - (0.205 only if Female))

Where:

e = 2.71828182845905

SCr = the serum creatinine, either expressed in mg/dL. When SCr is expressed in mol/L, the conversion rate that should be used is 88.4 mol/L = 1 mg/dL.

Note that in any case serum creatinine is less than 0.8 mg/dL, the Mayo Quadratic Formula uses 0.8 mg/dL default for SCr.

In the case of pediatric patients, the Schwartz formula is used:

GFR = 0.41 x Height (in cm) / SCr

The optimal GFR level is around 60 mL/min/1.73 m2 level. The table below summarises the chronic kidney disease stages and their associated glomerular filtration rates:

 CKD stage GFR level (mL/min/1.73 m2) Other observations 0 Stage - Normal kidney function ≥90 No proteinuria 1st Stage ≥90 Kidney damage signs 2nd Stage 60 – 89 Mild 3rd Stage 30 – 59 Moderate 4th Stage 15 – 29 Severe 5th Stage <15 Kidney Failure

References

1. Guyton, Arthur; Hall, John (2006) Chapter 26: Urine Formation by the Kidneys: I. Glomerular Filtration, Renal Blood Flow, and Their Control. In Gruliow, Rebecca. Textbook of Medical Physiology (Book) (11th ed.) Philadelphia, Pennsylvania: Elsevier Inc.

2. Mathew TH, Johnson DW, Jones GR. Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: revised recommendations. The Medical Journal of Australia. 2007; 187 (8): 459–63.

3. Jin R, Grunkemeier GL, Brown JR, Furnary AP. Estimated glomerular filtration rate and renal function. Ann Thorac Surg. 2008; 86(1):1-3.

4. Kampmann JP, Hansen JM. Glomerular filtration rate and creatinine clearance. Br J Clin Pharmacol. 1981; 12(1): 7–14.

Specialty: Nephrology

System: Urinary

Objective: Determination

Type: Calculator

No. Of Variables: 4

Article By: Denise Nedea

Published On: July 2, 2017 · 08:01 AM

Last Checked: July 2, 2017

Next Review: July 2, 2023