Pediatric GFR Calculator - Glomerular Filtration Rate

Glomerular filtration rate, or GFR for short, is a test for determining kidney disease risk. It can be calculated from your blood test results (from creatinine levels, to be precise).

The unit of GFR is mL/min/1.73m². The value 1.73m² is the standardized body area. Because the body area is different for kids at various ages, the equations listed below take into consideration the height factor.

Are you interested in counting the body surface area (BSA)? Try our tool, BSA calculator, for that!

According to the National Kidney Foundation, there are three main ways to estimate the GFR of children. Our pediatric GFR calculator uses all of them so that you can compare all results and see whether all of them are in the normal range.

1. Creatinine-based “Bedside Schwartz” equation (2009)

This is the standard - and the best method - for estimating GFR in children aged 1-18. Since it was updated in 2009, it no longer returns overestimated results.

GFR = 41.3 × (height / Scr)

where:

• height is expressed in meters; and
• SCr is the level of standardized serum creatinine in mg/dL.

2. Cystatin C-based equation (2012)

This formula uses the level of serum cystatin C instead of the creatinine indicator. It is an excellent confirmatory test and a recommended one if the levels of creatinine are fluctuating.

eGFR = 70.69 × Scys^-0.931

where:

• Scys is the level of standardized serum cystatin C in mg/L.

3. Creatinine-Cystatin C-based CKiD equation (2012)

This test uses both creatinine and cystatin C indicators. It is an excellent confirmatory test, too.

GFR = 39.8 × (height/Scr)^0.456 × (1.8/Scys)^0.418 × (30/BUN)^0.079 × a × (height/1.4)^0.179

where:

• height is expressed in meters;
• a is a coefficient dependent on sex: 1 for females, 1.076 for males;
• BUN is the level of blood urea nitrogen in mg/dL;
• Scys is the level of standardized serum cystatin C in mg/L;
• SCr is the level of standardized serum creatinine in mg/dL.

The table below shows the typical values of GFR on different stages of kidney malfunction.