Wednesday, May 1, 2024
HomeExclusiveHow Do You Calculate Kidney Function Percentage

How Do You Calculate Kidney Function Percentage

How Is A Creatinine Test Done

How Is Kidney Function Measured?

There are two main ways doctors use creatinine tests to measure kidney function:

  • Urine tests. Creatinine clearance can be pinpointed by measuring the amount of creatinine in a sample of pee collected over 24 hours. For this method, you store all your urine in a plastic jug for one day and then bring it in for testing. This method is inconvenient, but it may be necessary to diagnose some kidney conditions.

  • Blood tests.Doctors can estimate GFR using a single blood level of creatinine, which they enter into a formula. Different formulas take into account your age, sex, and sometimes weight and ethnicity. The higher the blood creatinine level, the lower the estimated GFR and creatinine clearance.

For practical reasons, the blood test method for GFR is used far more often than the 24-hour urine collection test for creatinine clearance. But urine collections may still be useful in people who have large muscle mass or a marked decrease in muscle mass.

Stage 5gfr Of 15 Ml/min Or Less

Patients at Stage 5 have chronic CKD. They have a GFR of 15 mL/min or less and have End Stage Renal Disease .The kidneys have lost almost all ability to function effectively at this stage. They will need dialysis or a kidney transplant to live.

Our kidney specialists can work with you to provide individualized evaluation and treatment, taking into consideration your GFR and other factors. To learn more or schedule an appointment at one of our clinics call 412-802-3043 or toll free 1-800-533-UPMC .

You should discuss this result with your kidney specialist.

What Is The Evidence Behind Reporting Of The Egfr

As a result of the automatic reporting of eGFR, the clinical detection of kidney disease has significantly increased in the community.

In 2004, a clinical study involving 324 outpatients was performed to evaluate the effect of automatic laboratory reporting of eGFR with each request for serum creatinine. The effects on detection of chronic kidney disease were assessed. This automatic reporting was combined with education aimed at doctors involved in the study. The presence of an eGFR value, in conjunction with education significantly increased the detection of chronic kidney disease from 22.4% to 85.1% of patients. However, further research needs to be conducted regarding the significance and longer term outcomes resulting from this improved detection of chronic kidney disease. Last but not least, if the eGFR is normal, but there are other abnormal investigation results , the GFR should be calculated.

Also Check: Are Laxatives Bad For Your Kidneys

Top 7 Kidney Tests To Measure Your Kidney Function


Time has flown by once again, and therefore it is well and truly time to write my next article to help those with kidney disease. Today I wanted to cover a very important topic: kidney tests.

Kidney tests are the first stage of any great treatment program. There is no point coming in with guns a blazing if you dont know exactly what has caused your condition, what degree of deterioration your condition is at, and a general reference point of where you are beginning with treatment this is particularly important, as you want to know if all the good work is paying off!

As you are probably aware kidney disease is known as a silent killer. Typically because of late diagnosis, coming well after the damage has already been caused giving little time to treat. So if you are reading this right now with only a suspicion that something is afoot with your kidney/urinary tract health, please take this friendly suggestion and go and have your kidneys tested this week. This is of great importance it may just save your life, or better yet, give you a disease free, vital life .

Albuminuria: The Urine Albumin: Creatinine Ratio

Kidney Disease GFR Calculator

A simple urine test called the urine Albumin:Creatinine ratio is also performed to look for signs that protein is leaking into the urine . This is an important sign of kidney damage. The ACR is used to calculate the A stage of CKD .

There are three recognised stages of albuminuria:

  • A1 normal to mildly increased urine protein levels
  • A2 moderately increased urine protein levels
  • A3 severely increased urine protein levels

Combining your ACR ratio with your eGFR can help doctors try to predict whether your kidney disease is likely to progress and whether you are more likely to develop complications such as heart and circulatory problems. Other factors are also taken into account, e.g. age. In general, the higher the A stage, the more likely it is that you will benefit from blood pressure-lowering treatment.

Recommended Reading: Wine For Kidney Stones

Stages Of Kidney Disease In Children

Please note: The American Kidney Fund is committed to ensuring that every person receives health care that is fair, equitable and of the highest quality. The estimated glomerular filtration rate is an estimate of how well your kidneys are working. Currently the test considers your age, sex and race, among other things. A task force led by the National Kidney Foundation and the American Society of Nephrology has made recommendations to remove Black race as a factor in the eGFR calculation. The task force received input from patients, the community and kidney disease experts, including AKFs Medical Advisory Committee, to reduce bias in kidney function testing. AKF is reviewing the NKF-ASN recommendations and will update its outreach and educational programs ongoing as additional information and evidence evolves.

Kidney disease in children is diagnosed the same way it is in adults. A urine test, blood test, imaging test, or kidney biopsy can help determine if something is wrong with the kidneys.

The eGFR blood test shows how well the kidneys are working. The stages of kidney disease are decided by a persons eGFR. eGFR can be used to diagnose a childs stage of kidney disease once the child reaches age two.

How Does This Chronic Kidney Disease Calculator Work

This is a health tool that uses the CKD-EPI formula to estimate the glomerular filtration rate in a modern way.

The chronic kidney disease calculator requires you to input the serum creatinine level, either in mg/dL or umol/L, the age and select the gender and race in order to customize the formula and reveal the result.

Read Also: Is Celery Juice Good For Kidneys

Blood Urea Nitrogen Vs Creatinine

Blood urea nitrogen and creatinine are both metabolites, so they’re produced constantly by the body at a fairly steady pace. The difference lies in the way they behave in the nephron, the functional unit of the kidney. Creatinine is usually filtered, secreted directly into the lumen, and does not leave the lumen of the tubule. BUN is filtered and then reabsorbed back in the blood, so, naturally, we would have more BUN in the blood than creatinine.

If the BUN creatinine ratio is high, it’s usually connected to the low glomerular filtration rate. In this case, both metabolites get filtered poorly due to small flow, but urea ‘leaks out’ back to the blood which increases the ratio. If the ratio is low, it means that substances just passed the kidney, didn’t get filtered.

BUN creatinine ratio is just one of the parameters to assess kidneys. If we measure creatinine in urine, we are able to calculate fractional excretions – e.g., of sodium or urea. If the potassium is our concern, transtubular potassium gradient is more than useful. And if all we’ve got is the serum creatinine, we can estimate the GFR with creatinine clearance parameter.

What Should My Gfr Be For My Age

Kidney Function Test (creatinine, eGFR, creatinine clearance) Your Kidneys Your Health |@qasimbuttmd

If the glomerular filtration rate is low, it may indicate that the kidneys are not working as they should.

According to the National Kidney Foundation, a normal glomerular filtration rate in adults is above 90, though this ‘normal’ rate may differ based on age.

  • 20-29 years: 116
  • 60-69 years: 85
  • 70+ years: 75

It’s important to note that a low GFR may indicate kidney disease but early detection and treatment may help the kidney disease worsening.

Read Also: Is Cranberry Juice Good For Your Liver

Pcr Assay And Calibration

Pcr levels were measured in a single laboratory on a Hitachi 7600 analyzer using the Jaffeâs kinetic method, which was described elsewhere . To ensure that our Pcr values were calibrated equally to the MDRD study, we randomly selected 57 fresh-frozen plasma samples from our specimens and analyzed them in both our laboratory and the Cleveland Clinic Laboratory. The Pcr value that was measured by our laboratory can be calibrated to the Pcr value that was measured by the Cleveland Clinic Laboratory, which used a CX3 analyzer , using a linear regression equation: CX3 Pcr = â15.91 + 1.32 Ã Hitachi Pcr .

Estimate Glomerular Filtration Rate

Calculate estimated GFR from serum creatinine levels to assess kidney function.

Use of any serum creatinine-based estimate requires that kidney function be at a steady state. eGFR should be used with caution in acutely ill or hospitalized patients who may exhibit rapidly changing kidney function.

Adults: Use either the Modification of Diet in Renal Disease Study equation or the Chronic Kidney Disease Epidemiology Collaboration equation.

Patients under the age of 18: Calculate eGFR using the Schwartz equation for patients under age 18.

Caution: It is important to know the method used to measure creatinine in a blood, serum, or plasma sample, as it will affect the formula for estimating GFR in children.

Determine which calculator to use.

Recommended Reading: Celery Juice For Kidneys

Guideline : Estimation Of Gfr

The GFR is the best overall indicator of the level of kidney function. .1 The GFR should be estimated using a prediction equation that takes into account the serum creatinine level and some or all of these variables: age, sex, race, and body size. The Modification of Diet in Renal Disease study equation and the Cockcroft-Gault equation provide useful estimates of the GFR in adult patients .46 The NKF guideline1,2 notes that the serum creatinine concentration alone is not optimal for assessing the level of kidney function.

Equations for Predicting GFR in Adults Based on Serum Creatinine Concentration*

Abbreviated MDRD study equation:

Cockcroft-Gault equation:

GFR = glomerular filtration rate MDRD = Modification of Diet in Renal Disease SCr = serum creatinine concentration CCr = creatinine clearance.

*For each equation, SCr is in milligrams per deciliter, age is in years, and weight is in kilograms.

Information from references 4, 5, and 6.

Equations for Predicting GFR in Adults Based on Serum Creatinine Concentration*

Abbreviated MDRD study equation:

Cockcroft-Gault equation:

GFR = glomerular filtration rate MDRD = Modification of Diet in Renal Disease SCr = serum creatinine concentration CCr = creatinine clearance.

*For each equation, SCr is in milligrams per deciliter, age is in years, and weight is in kilograms.

Information from references 4, 5, and 6.


GFR = glomerular filtration rate MDRD = Modification of Diet in Renal Disease.

Egfr Is An Estimate Of Kidney Filtration

What Does It Mean When You Have 38 Percent Kidney Function

eGFR is an estimate of how well your kidneys are filtering. It is calculated from the result of a blood test along with your age and sex. As normal eGFR is round about 100, the eGFR gives you an approximate ‘percentage function’. So if your eGFR is 50, your kidneys are probably filtering at about 50% of normal. It’s very approximate though, and there are times when it can’t be very reliable at all. It is not accurate at near-normal levels, so many labs report eGFR over 60 as just “> 60” .

You May Like: Osteocleanse

What Is Renal Function What Does Gfr Mean

Your health care team may talk about the work your kidneys do in terms of “kidney function”. If you have two healthy kidneys, you have 100 percent of your kidney function. This is more than you really need. Some people are born with only one kidney and are still able to live a normal and healthy life. Many people donate a kidney for transplantation to a family member or friend and continue to have a relatively normal kidney function. Small declines in renal function do not necessarily cause a problem.1

However, many people with reduced kidney function have a kidney disease that will worsen over time. Serious health problems occur when kidney function declines to less than 25 percent. If it drops below 10 to 15 percent, a person cannot live long without some form of renal replacement therapy – either dialysis or transplantation.1

If you know your current blood creatinine level, you can use our GFR Calculator to estimate your kidney function.

The GFR is used for defining the stages of chronic kidney disease.

Modification Of Original Mdrd Equations

A total of 720 participants were included, and 36 outliers were deleted. The remaining 684 patients were used for further analysis. From these patients, 454 were randomly selected and used for the training model, and the remaining 230 patients were used to test the performance of the modified equations.

We assumed that the performances of MDRD equations could be improved in Chinese patients with CKD by adding a racial factor, so 7GFR and aGFR were calculated on the basis of data from the 454 training samples using 7GFR and aGFR as dependent variables, respectively, two linear regression models were established to predict rGFR from 7GFR or aGFR. It was decided that if the intercepts of the two models were not significantly different from zero, then the models should be simplified by forcing the intercepts to be zero.

You May Like: Can Kidney Stones Make You Constipated

Gfr Levels And Ckd Stages

Normal filtration rate should be of 100 but GFR levels are considered normal when they go above 90mls/min/1.73m2. This is valid as long as there arent any other signs of chronic disease, in such case being considered stage 1. A GFR level between 60-90 is to be considered of stage 2 if there are symptoms present.

CKD means that kidneys are not functioning properly and the severity of it can vary from mild to moderate, especially in older people to progressing to kidney failure.

What it is very serious is stat people with any stage of CKD are at risk of heart disease or stroke. Diagnosing chronic kidney disease requires two measurements of creatinine and two estimations of GFR at 90 days apart.

The below table exemplifies the 5 stages of CKD.


Calculation Of Reabsorption And Secretion Rates

Can you reverse kidney disease? How I improved my kidney function

– The reabsorption or secretion rate is the difference between the amount filtered across the glomerular capillaries and the amount excreted in urine. It is calculated with the following equations:

Filtered load = GFR x Excretion rate = V x Reabsorption rate = Filtered load – Excretion rate Secretion rate = Excretion rate – Filtered load

– If the filtered load is greater than the excretion rate, then net reabsorption of the substance has occurred. If the filtered load is less than the excretion rate, then net secretion of the substance has occurred.

Table 5-3. Effect of Changes in Starling Forces on GFR, RPF, and Filtration Fraction

Effect on GFR

GFR = glomerular filtration rate RPF = renal plasma flow.

GFR = glomerular filtration rate RPF = renal plasma flow.



Figure 5-4. Processes of filtration, reabsorption, and secretion. The sum of the three processes is excretion.

– Example: A woman with untreated diabetes mellitus has a GFR of 120 ml/min, a plasma glucose concentration of 400 mg/dl, a urine glucose concentration of 2500 mg/dl, and a urine flow rate of 4 ml/min. What is the reabsorption rate of glucose?

Filtered load = GFR x Plasma = 120 ml/min x 400 mg/dl = 480 mg/min Excretion = V x Urine

= 4 ml/min x 2500 mg/dl = 100 mg/min Reabsorption = 480 mg/min – 100 mg/min = 380 mg/min

Continue reading here: Reabsorption of glucose

Was this article helpful?

Don’t Miss: Is Wine Good For Kidney Stones

Stages Of Kidney Disease In Children And Adults Ages 2+

Stage 1

Kidney damage with normal or increased GFR

eGFR 90 or above and other signs of kidney damage present

Stage 2

Kidney damage with mild decrease GFR

eGFR 60-89 and other signs of kidney damage present

Stage 3a

Mild to moderate decrease GFR

eGFR – 45-59

Stage 3b

Moderate to severe decrease GFR

eGFR – 45-59

Stage 4

eGFR – 15-24

Stage 5

How Does This Gfr Calculator Work

This health tool will evaluate and retrieve the overall index of kidney function for adults and children in two separate tabs by taking account of the serum creatinine level, age, sex and race.

In order to accomplish this task it returns the GFR value based on a few creatinine equations that will be described below. Once you enter the requested information the GFR calculator will be ready to offer the detailed information.

Recommended Reading: Is Watermelon Bad For Kidneys

How To Calculate Your Gfr

Estimating GFR begins with a simple serum creatinine blood test. If youre using our GFR calculator, your eGFR is calculated using the results of your blood test, along with your age, ethnicity, and gender. When your eGFR is calculated by your doctor, weight and body size may also be factored into your eGFR.

Modification Of Diet In Renal Disease Formula

Renal function kidney

More recently Levey et al introduced a formula derived from data on patients with advanced renal failure in the modification of diet in renal disease study.- This is referred to as the 6-variable MDRD or 6-v MDRD formula. This formula gives an estimate of glomerular filtration rate in millilitres per minute adjusted for body surface area of 1.73 m2 and is based on a patient’s age, sex, race, and levels of serum urea, serum creatinine, and serum albumin. By avoiding inclusion of weight, the formula is less prone to errors from fluid overload and obesity.

In 2000 a simplification of the modification of diet in renal disease formula using only patient’s age, sex, race, and serum creatinine level was derived from the original data. This is referred to as the 4-variable MDRD or 4-v MDRD formula. With the exception of race, the other variables required are normally provided routinely when a sample is submitted to the laboratory. It is therefore much easier for laboratories to report estimated glomerular filtration rate using this formula.

Also Check: Is Red Wine Good For Kidney Stones


Most Popular