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What Test Measures Kidney Function

Estimated Glomerular Filtration Rate

Kidney Function Tests and Interpretation of Results.

The eGFR kidney test is a test that estimates the total blood filtered through the kidneys every minute. Healthy kidneys filter 90ml to 120ml every minute of every hour. This occurs through the glomerular capillaries of the kidneys, hence the name.

Originally the test was known as the Glomerular Filtration Rate test the calculation required a substance to be injected into the bloodstream, then collection of the urine that passed for a 24hr period, and finally a test to measure how much of the substance found its way in to the urine collected. Thankfully scientists discovered they could easily estimate the kidney function with great accuracy without needing to use this original testing procedure making it a far simpler kidney test.

The results of the eGFR test certainly give some of the most useful information about your kidney health out of all kidney tests. You see, whatever figure comes back as your result , you can in fact replace the ml/min at the end of the result lets use 55ml/min as an example with a % instead. So in this example, 55ml/min will become 55%.

What does this mean? Well, this figure can literally be used to show the total percentage of kidney function you have This person has 55% of their kidney function left. Important number to know, am I right?

Note: eGFR kidney test requires the following information to calculate the result: creatinine serum levels , age, sex, and race.

Nutrition And Low Kidney Function

Food is what our bodies use for growth, homeostasis, and healing. This is why its important for you to consult with a dietician who is knowledgeable about kidney disease. Youll need to find and maintain a balance between the levels of electrolytes, minerals, and fluid in your body.

A modified diet for chronic kidney disease may include adjustments to your intake of the following food items:

Blood Urea Nitrogen Test

The blood urea nitrogen test checks for other waste products in the blood, such as urea nitrogen.

Urea nitrogen occurs as proteins from food break down, and elevated levels may be a sign that the kidney is not filtering these waste products effectively.

A typical BUN level falls between 7 and 20 milligrams per deciliter. Higher values could be a sign of an underlying condition affecting the kidneys.

With that said, many other things can affect BUN levels, such as medications or antibiotics. A diet that is very high in protein diet may also affect levels.

Doctors will typically compare these results to the results of a creatine test to get a better understanding of how well the kidney is filtering this waste.

Imaging tests may help doctors identify any physical changes to the kidneys, such as injuries or kidney stones.

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About Normal Ranges And Interpreting The Numbers

When you look at a printout of your lab results, youll find the normal ranges for each blood test next to your personal results. For example, if your routine blood work includes a test for calcium in the blood, your lab may list the normal range for calcium as 8.3 to 9.9 milligrams per deciliter . If your result is a 9.1 mg/dL, right in the middle, you can feel confident that your calcium level is normal.

But what if a blood test result is at the very low or high end of normal, or even slightly outside the normal range? Is that a red flag? Dont jump to conclusions, warns Dr. Salamon. Blood test results can vary a little bit, depending on the lab. And many people are consistently on one side or the other of the normal range, and for them, thats healthy, says Dr. Salamon.

Take, for example, a routine measure of blood urea nitrogen , a waste product created as your body breaks down the protein in your diet. Excess urea is removed from the blood by the kidneys, so high levels of BUN in the blood can indicate that kidney function is declining. So, what does it mean if your BUN level is at the very high end of the normal range? If I see that its borderline high, I might ignore it, says Dr. Salamon. Its common for BUN to go up if you dont drink enough, and that can happen when someone is fasting before having blood drawn.

Minor fluctuations in test results may also reflect

  • recent infections

What Is A Kidney Function Blood Test

World Kidney Day 2018

The kidney function blood test measures the level of creatinine, urea and certain dissolved salts.

  • Creatinine is a waste product in your body that is made by your muscles. It passes into your bloodstream, and is usually passed out in urine . A high blood level of creatinine indicates that your kidneys may not be working properly.
  • Urea is produced when protein is broken down by your body. Healthy kidneys eliminate more than 90% of the urea your body produces. A high blood level of urea may indicate that you are dehydrated or that your kidneys may not be working properly.
  • Dissolved salts that are routinely measured are sodium, potassium, chloride and bicarbonate. They are sometimes referred to as ‘electrolytes’. Abnormal blood levels of any of these may sometimes be due to a kidney problem.
  • eGFR stands for estimated glomerular filtration rate. Although the level of creatinine in your blood is a useful guide to kidney function, the eGFR is a more accurate measure of how well your kidneys are filtering your blood. Using your blood creatinine, and your age and sex, your eGFR can be calculated by computer and reported with the creatinine blood test.

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Tests To Measure Kidney Function Damage And Detect Abnormalities

Healthy kidneys remove wastes and excess fluid from the blood. Blood and urine tests show how well the kidneys are doing their job. Urine tests can show how quickly body wastes are being removed and whether the kidneys are leaking abnormal amounts of protein. Here’s a quick guide to the tests used to measure kidney function.

Other Tests Of Kidney Function

The routine kidney blood test is a general marker of kidney function. If the blood test is abnormal it cannot say what is causing the kidney problem. Therefore, if you have an abnormal result you may need further tests to find the cause of a kidney problem. For example: urine tests, other blood tests, scans, X-rays, kidney biopsy, etc.

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How Is A Renal Panel Test Different From A Creatinine Clearance Test

A creatinine clearance test includes both a blood and urine sample. The amount of creatinine is measured in each sample, and then the two figures are compared. This comparison provides a method for estimating the glomerular filtration rate and evaluating kidney function.

In contrast, a renal panel uses only a blood sample. While a standard renal panel measures creatinine in the blood, it does not include a urine collection or comparative measurement.

The renal panel also includes a more diverse set of measurements, including proteins, minerals, and electrolytes, than a creatinine clearance test.

Are All Renal Panel Tests The Same

Kidney Function Tests, Animation

It is common for there to be some variation in the individual components of a renal panel based on the specific laboratory that performs your test. However, some test elements, such as the electrolytes, glucose, calcium, phosphorus, and albumin are found on the most common renal panel tests offered by major laboratories.

In addition, your doctor can request that other specific measurements be included with your renal panel. You will see a line item for each component when you review your test report, and your doctor can explain the significance of each component and the results in the context of your health situation.

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Normal Kidney Function And The Gfr

All the blood in your body flows through your kidneys hundreds of times each day. The kidneys push the liquid part of blood through tiny filters called nephrons and then reabsorb most of the fluid back into the blood. Fluid and waste products that the kidneys don’t reabsorb are sent out of your body in your urine.

The rate of blood flow through your kidneys is the GFR. Your doctor canât measure the GFR itself, so that’s where creatinine and creatinine clearance come in.

What If My Test Results Show Early Kidney Disease

If a test shows irregular results, your healthcare provider will follow up with you about treatment options. You may receive medications to control blood pressure. Or you may follow up with a nephrologist .

If your test results are atypical, your provider will likely order more frequent kidney function tests in the future. Regular testing helps your provider track your health and any underlying conditions.

A note from Cleveland Clinic

Kidney function tests check how well your kidneys are working. Healthy kidneys assist with removing waste from your body. Conditions such as diabetes or high blood pressure can affect your kidney function. You may also need a kidney function test to diagnose or rule out an infection. Kidney function tests include blood tests or urine tests. Typically, your provider gives you your results the same day or within a few days.

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What The Experts Recommend

For people with type 2 diabetes, the guidelines in Canada are clear. Screening for kidney disease should:

  • Start at diagnosis of type 2 diabetes.
  • Be repeated annually .
  • Include both blood and urine tests.

You may think youâre not at risk for kidney disease since you havenât had diabetes for very long. Or maybe you think you have nothing to worry about because you havenât had any symptoms to suggest you have kidney disease.

But the reality is that the kidneys may already be damaged by the time type 2 diabetes is diagnosed. And there are often no symptoms of kidney disease until it has advanced to a more severe stage. Thatâs why Diabetes Canada recommends annual screening starting right away when youâre diagnosed with T2D.

What Do The Results Of My Kidney Function Test Mean

High Reading On Kidney Blood Test

Kidney function test results can tell you whether your kidneys are functioning typically or not. Most function tests look for two measurements:

  • GFR of less than 60 could indicate kidney disease.
  • Urine albumin-to-creatinine ratio of more than 30 milligrams per gram could be a warning sign of kidney disease.

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What Happens If You Have Kidney Disease

Kidney disease can be treated. The sooner you know you have kidney disease, the sooner you can get treatment to help delay or prevent kidney failure. Treating kidney disease may also help prevent heart disease.

Treatment goals are to:

  • If you smoke, take steps to quit.
  • Take medicines the way your provider tells you to.

How Is A Renal Panel Different From A Comprehensive Or Basic Metabolic Panel

There is considerable overlap between the measurements on a renal panel, basic metabolic panel , and comprehensive metabolic panel .

The BMP has 8 components, all of which are included in the CMP, which has a total of 14 measurements. The components of the BMP and CMP are more standardized than the renal panel, which can vary between laboratories.

The BMP, CMP, and most renal panels include measurements of glucose, electrolytes, calcium, and the waste products creatinine and urea nitrogen. The CMP and many renal panels also include measurement of albumin.

An important difference for the comprehensive metabolic panel is its inclusion of tests that help assess the condition of the liver. These are tests found on a typical liver panel test.

Because it is not as standardized, a renal panel test may include measurements, such as phosphorus or the anion gap, that are not found on the BMP or CMP.

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What Does The Test Measure

A renal panel includes multiple measurements. However, not all renal panel tests are exactly the same. The components can depend on the laboratory or the measurements requested by the doctor prescribing the test.

The most common components tested in most renal panels include:

Other measurements that may also included in a renal panel include:

  • Anion gap: The anion gap is a comparison of different electrolytes. Specific electrolytes can be positively or negatively charged, and this test assesses the balance between the two types. This measurement helps determine if you have too much or too little acid in your blood.
  • Estimated glomerular filtration rate : The eGFR is an evaluation of kidney function. Glomeruli are tiny filters in the kidneys, and the eGFR is a calculation of how much blood they are filtering every minute. There are different ways to calculate eGFR, but most tests use a special formula based on your creatinine level.
  • Total protein: There are several kinds of proteins that can be found in the blood, and total protein is a count of all of them. These proteins include albumin and multiple types of globulins, which are made by the immune system.
  • BUN-to-creatinine ratio: In some cases, comparing the amounts of the waste products BUN and creatinine can provide information about whether abnormal levels are being caused by problems in the kidneys or another part of the body..

Components Of Kidney Function Test

Kidney function| blood test| malayalam

The components of the Kidney function test could be broadly divided into two categories.

The tests that are part of the Kidney Function test panel are:

  • Urine examination
  • Dilution Test

Urine Examination

This examination consists of a physical examination where the color, odor, quantity, specific gravity etc of the urine is noted. Microscopic examination of urine is done to weed out any pus cells, red blood cells casts, Crystals etc.

Serum Urea

Urea is the end product of the protein catabolism. The urea is produced from the amino group of the amino acids and is produced in the liver by means of the Urea cycle. Urea undergoes filtrations at the glomerulus as well as secretion and reabsorption at the tubular level. The rise in the level of serum urea is generally seen as a marker of renal dysfunction especially glomerular dysfunction. Urea level only rises when the glomerular function is reduced below 50%. The normal serum urea level is between 20-45 mg/dl. But the level might also be affected by diet as well as certain non-kidney related disorders. A high protein diet might increase the blood urea level. Similarly, a low protein diet might decrease blood urea level.

Blood Urea Nitrogen


Normal Results: 8.5 to 10.2 mg/dlC

Serum Creatinine Level

Dilution Test

Stay tuned with BYJUS to know more in detail about the kidney, kidney function test and importance of excretory system.

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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.

Blood Urea Nitrogen Vs Creatinine

Blood urea nitrogen and creatinine are both metabolites, so theyâre 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, itâs usually connected to the low glomerular filtration rate. In this case, both metabolites get filtered poorly due to small flow, but urea âleaks outâ back to the blood which increases the ratio. If the ratio is low, it means that substances just passed the kidney, didnât 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 â e.g., of sodium or urea. If the potassium is our concern, transtubular potassium gradient is more than useful. And if all weâve got is the serum creatinine, we can estimate the GFR with creatinine clearance parameter.

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How Do Physicians Test Your Kidney Function

Jun 6, 2018 | Healthy Tips


By Veeraish Chauhan, MD

A common misconception that people often have is equating urine output to kidney function. Hence, the assumption is that if you are making urine, your kidneys are working just fine. However, nothing is further from the truth, and assessing the function of your kidneys requires lab testing and sometimes radiological imaging.

Most people know that getting a stress test is a way to test your hearts function.

But how do you test your kidney function? You might have heard doctors mention words like creatinine or GFR when checking how good or bad your kidneys are doing. Although there are a lot of methods by which the kidneys performance can be measured, I will explain the ones that are used most often in a clinical setting.

Broadly speaking, you could check kidney function through either:

Radiological imaging

Blood Tests

This is the most common and usually the most reliable method. Doctors will often order tests that could be variously worded like basic metabolic panel ,chem 7,renal function panel,GFR, etc. Essentially, what they are measuring is the levels of electrolytes and two other chemicals called blood urea nitrogen and creatinine.

BUN measures the amount of nitrogen present in your blood in the form of urea, hence the name BUN! In other words, what we are measuring is the urea level in the blood.

BUN: An Imperfect Test

Creatinine Is a Better Alternative


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