GFR Calculator
Glomerular Filteration Rate (GFR)Glomerular filtration rate (GFR) is the best overall index of kidney function. Normal GFR varies according to age, sex, and body size, and declines with age. Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit time. Glomerular filtration rate (GFR) can be calculated by measuring any chemical that has a steady level in the blood, and is freely filtered but neither reabsorbed nor secreted by the kidneys. The rate therefore measured is the quantity of the substance in the urine that originated from a calculable volume of blood. The GFR is typically recorded in units of volume per time, e.g., milliliters per minute ml/min. Compare to filtration fraction. There are several different techniques used to calculate or estimate the glomerular filtration rate (GFR or eGFR). The Most recent techniques are CKD EPI and MDRD GFR Formula. The details of these GFR Calculation formulas can be see after the calculator. The following GFR Calculator is based on these new GFR Calculation techniques. 



Estimated GFR (eGFR) using Modification of Diet in Renal Disease (MDRD) formulaThe most recently advocated formula for calculating the GFR is the one that was developed by the Modification of Diet in Renal Disease Study Group. Most laboratories in Australia, and The United Kingdom now calculate and report the MDRD estimated GFR along with creatinine measurements and this forms the basis of Chronic kidney disease#Staging. The adoption of the automatic reporting of MDRDeGFR has been widely criticised. The most commonly used formula is the "4variable MDRD," which estimates GFR using four variables: serum creatinine, age, race, and gender. The original MDRD used six variables with the additional variables being the blood urea nitrogen and albumin levels. The equations have been validated in patients with chronic kidney disease; however both versions underestimate the GFR in healthy patients with GFRs over 60 mL/min. The equations have not been validated in acute renal failure. For creatinine in mg/dL: For creatinine in µmol/L:
A more elaborate version of the MDRD equation also includes serum albumin and blood urea nitrogen (BUN) levels:
These MDRD equations are to be used only if the laboratory has NOT calibrated its serum creatinine measurements to isotope dilution mass spectrometry (IDMS). When IDMScalibrated serum creatinine is used (which is about 6% lower), the above equations should be multiplied by 175/186 or by 0.94086. Since these formulae do not adjust for body mass, they (relative to the CockcroftGault formula) underestimate eGFR for heavy people and overestimate it for underweight people. (see CockcroftGault formula above). Estimated GFR (eGFR) using the CKDEPI formulaThe CKDEPI (Chronic Kidney Disease Epidemiology Collaboration) formula was published in May 2009. It was developed in an effort to create a formula more accurate than the MDRD formula, especially when actual GFR is greater than 60 mL/min per 1.73 m2. Researchers pooled data from multiple studies to develop and validate this new equation. They used 10 studies that included 8254 participants, randomly using 2/3 of the data sets for development and the other 1/3 for internal validation. Sixteen additional studies, which included 3896 participants, were used for external validation. The CKDEPI equation performed better than the MDRD (Modification of Diet in Renal Disease Study) equation, especially at higher GFR, with less bias and greater accuracy. When looking at NHANES (National Health and Nutrition Examination Survey) data, the median estimated GFR was 94.5 mL/min per 1.73 m2 vs. 85.0 mL/min per 1.73 m2, and the prevalence of chronic kidney disease was 11.5% versus 13.1%. The CKDEPI equation, expressed as a single equation, is: where SCr is serum creatinine (mg/dL), k is 0.7 for females and 0.9 for males, a is 0.329 for females and 0.411 for males, min indicates the minimum of SCr/k or 1, and max indicates the maximum of SCr/k or 1. A clearer version may be as follows: For creatinine (IDMS calibrated) in mg/dL: If serum creatinine (Scr) > 0.7 African American Male If serum creatinine (Scr) > 0.9 White or other race Female If serum creatinine (Scr) > 0.7 White or other race Male If serum creatinine (Scr) > 0.9 This formula was developed by Levey et al. The formula CKDEPI may provide improved cardiovascular risk prediction over the MDRD Study formula in a middleage population. You can either use these GFR calculation formula's or use our GFR Calculator above to automatically calculate your Glomerular Fileration Rate ior GFR.
