Expanded Kidney Function Panel

Test Quick Guide

Renal function tests (or renal panel) are a series of tests that examine how well the kidneys are working in removing waste products (urea, toxins, uric acid) and extra water from the blood (urine) and ensuring proper balance of key chemical elements such as sodium, potassium, calcium, etc. They also are essential in producing certain hormones that are necessary in the production of red blood cells, maintaining blood pressure, and bone development.This panel test is performed using a blood sample and can play a role in the early detection, diagnosis, and monitoring of kidney problems.

About the Test

Purpose of the test

The purpose of a renal panel test, which may be casually referred to as a kidney test or a kidney function test, is to find or rule out potential kidney impairment or disease. Depending on the circumstances, it may be used for diagnosis, screening, or monitoring.

  • Diagnosis is the identification of a health problem after signs or symptoms have started. Your doctor may order a renal panel if the doctor believes your symptoms could be related to an issue affecting the kidneys.
  • Screening is testing with the goal of early detection of a problem. Screening tests are done before any symptoms have occurred. If you are at higher risk of developing kidney disease, a renal panel may be prescribed to try to identify problems at an earlier stage.
  • Monitoring is how your situation can be tracked over time. Repeat testing with a renal panel can show if a condition of the kidneys is getting better or worse. This monitoring may be done after treatment for kidney disease. It can also be used to watch for changes to kidney function when taking medications that can cause kidney impairment.

What does the test measure?

A renal function 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:

  • Glucose: Also known as blood sugar, glucose provides energy for the body. Excess glucose in the blood, though, can be a sign of metabolic problems like diabetes.
  • Phosphorus:: Phosphorus is an essential mineral for your bones, teeth, nervous system, and muscles. Phosphorus comes primarily from the foods and drinks that you consume.
  • Calcium: Calcium is a mineral that is vital for the bones, muscles, cardiovascular system, and nervous system. The main source of calcium is through your diet with the body storing calcium in your bones.
  • Potassium: Potassium is one of several electrolytes. Electrolytes are minerals that enable acid-base balance, healthy fluid levels, and proper functioning of muscles and nerves. Potassium comes from your diet and is found throughout the body.
  • Sodium: Sodium is another electrolyte that comes from your diet, and the amount of sodium in the body is largely controlled by the kidneys.
  • Chloride: Chloride is an electrolyte that works in conjunction with other electrolytes to carry out various functions, including preserving a healthy balance of fluids.
  • Bicarbonate: Bicarbonate is another electrolyte. Levels of bicarbonate help assess the amount of carbon dioxide (CO2) in your blood.
  • Albumin: Albumin is a protein that is produced in the liver and found in the blood. It carries important substances through the body and helps maintain the proper pressure in the blood vessels so that fluids do not leak out of the blood.
  • Creatinine: Creatinine is a waste byproduct that is consistently formed as a result of normal muscle activity. The kidneys remove creatinine from the blood so that it can be carried out of the body in urine.
  • Blood urea nitrogen: (BUN): Urea nitrogen, sometimes just called urea, is a waste product from protein metabolism. This process produces ammonia which is then converted to a less toxic form, urea. Like creatinine, it is removed from the blood by the kidneys and cleared from the body in urine.

Other measurements that may also be included in a renal panel are:

  • Anion gap: The anion gap is a calculation that identifies an imbalance in  electrolytes. Specific electrolytes can be positively charged (e.g., sodium or potassium) or negatively charged (e.g., bicarbonate or chloride).  This test assesses the balance between the two types to determine if you have too much (acidosis) or too little acid (alkalosis) in your blood.
  • Estimated glomerular filtration rate: (eGFR): 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 the kidneys 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 BUN to creatinine can suggest a variety of problems such as a decrease of blood flow to the kidneys, a gastrointestinal bleed (GI bleed), a significant dietary increase of protein, malnutrition, or liver disease. An elevated ratio, normally between 10:1 to 20:1, reflects the possibility of one of these problems.

When should I get a renal panel?

A renal panel test can be used in a range of circumstances, and your doctor may include specific measurements depending on your situation.

As a diagnostic test, a renal panel is most frequently used when you have symptoms that could be explained by a kidney problem. Examples of symptoms that can be tied to kidney impairment or disease include:

  • Urinary changes that may include frequency, quantity, or appearance of your urine
  • Unexplained swelling, especially in your arms, hands, legs, and/or face
  • Itching
  • Loss of concentration
  • Appetite changes
  • Difficulty breathing
  • Nausea and/or vomiting
  • Fatigue
  • Muscle cramps or pain

A test like the renal panel may also be used for diagnosis when you have general symptoms without a clear cause or are being evaluated in an urgent care or emergency setting.

As a screening test, the renal panel or other tests of kidney health are most often prescribed if you have certain risk factors for kidney disease. Some of these risk factors include high blood pressure, diabetes, and a family history of kidney disease.

For people with an elevated risk of kidney problems, screening with a renal panel may be part of normal health checkups. Screening of this type is not standard in people who do not have risk factors.

A renal panel can be used to monitor a past kidney problem or as follow-up if you have already had an abnormal renal panel test. If you are receiving treatment for kidney injury or disease, a renal panel may be used to gauge your response to that therapy.

If you are going to have a medical procedure or take any drugs that can impair kidney function, your doctor may prescribe a renal panel before and/or after to monitor for possible kidney-related side effects.

Finding a Renal Panel

How can I get a renal panel?

In general, a renal panel is ordered by a doctor, and the blood sample is drawn in a medical office, laboratory, or hospital. Renal panels also go by a variety of different names including expanded kidney function panel and comprehensive kidney function panel.

Can I take the test at home?

Few options exist for complete renal panel testing that can be taken with an at-home test kit. Some at-home kidney tests involve taking a fingerstick blood sample at home and sending it to a lab for analysis, but these tests do not include all of the same measurements that are included in a typical renal panel test. However, you can order these tests online and take them locally at a participating laboratory.

How much does the test cost?

There is no universal fixed price for a renal panel test.

Different charges that can figure into the total price include office visits, fees related to the blood draw procedure, and costs of laboratory analysis. How much is billed for these charges can depend on several factors including:

  • Where the blood draw is performed
  • The laboratory that performs the testing
  • The specific measurements included in the renal panel
  • Whether you have health insurance

Many health insurance plans will cover some or all of the costs of a renal panel if the test is prescribed by your doctor and appropriate documentation as to why the test was ordered, but some costs, such as a deductible or copays, may still have to be paid out of pocket.

For more detailed information about what will be covered and your expected costs, talk directly with your doctor’s office and your health insurance company. Tests that can be ordered from home range from $39 to $99 depending on what they measure.

Taking a Renal Panel

A blood sample is necessary for a renal panel test and can be taken with a routine blood draw at a doctor’s office, hospital, or medical laboratory.

Before the test

For many renal panel tests, you will need to fast for 8 to 12 hours before your blood draw. During this time, you can only drink water. You cannot eat any food or drink other beverages.

However, because the exact components of a renal panel test can vary, you should ask your doctor whether you need to fast beforehand.

You should also tell your doctor about any prescriptions, over-the-counter medications, or supplements that you take. If any of these can affect the test, your doctor may ask you to temporarily stop taking them before the test.

During the test

When it’s time for your test, you will be seated while a phlebotomist or nurse prepares to draw your blood. They will tie a band around your upper arm to enhance blood flow to the vein in your arm. An antiseptic wipe will be used to clean the skin around your vein, allowed to dry, and then a needle will be inserted into the vein. The needle is used to withdraw an appropriate amount of blood and placed in a special test tube, and then removed from your arm.

This type of blood draw is a routine procedure that normally lasts only a few minutes. You may experience some brief pain or a stinging as the needle is placed in your arm.

After the test

When the needle is removed from your arm, a cotton swab will be used to stop any further bleeding, and a bandage placed over the puncture site to minimize any further bleeding or bruising. You may experience some soreness or bruising, but these effects are rarely long-lasting.

If you are required to fast, you may want to bring a snack to eat immediately after the test. Once your blood draw is finished, you can return to most normal activities, including driving.

Renal Panel Test Results

Receiving test results

The results from a renal panel test typically become available in a few business days. The full test report may be sent to you by mail or made accessible electronically. Your doctor may also call or email to review the results with you directly.

Interpreting test results

The test report from a renal panel will show separate line items for each component of the test. Every line item will show the measurement in your sample as well as the reference interval for the laboratory that did the testing.

For many components of the test, each lab is required to set the range for each test based on its analytic methods that may include differences in gender, age, and race. Accordingly, interpretation of your test result must be done in relation to the laboratory ranges listed on your test report and other clinical factors that can be discussed with your health care practitioner.

Examples of reference ranges for adults are listed in the table below. While your test values may be slightly different and fall outside the ranges noted below, each report contains the performing laboratory’s established reference ranges that should be used.

The exact components of the renal panel can vary, so you may not see all of these line items on your test. You may also see other measurements that were included by the laboratory or that were requested by your doctor. For each component, though, you should see the laboratory’s reference interval clearly displayed.

Interpretation of your test is always done within the context of your particular situation. This means considering your health history, current health and symptoms, and the results from any other medical tests you’ve taken.

Abnormal test results may be an indication of a health problem or an issue affecting the kidneys. However, doctors rarely rely on one single test result alone. Instead, they may look for patterns in which measurements are abnormal and how high or low those levels are compared to the corresponding reference ranges.

It is important to take these diverse factors into account in order to understand the significance of your renal panel test. For that reason, the test result should always be reviewed with your doctor who can best explain what the test shows and what it means for your health and wellness.

When your test results are ready, you can learn more about their significance by discussing them with your doctor. Some questions that you can ask include:

  • Were there any abnormal findings on my renal panel test? If so, what were they?
  • For any abnormal findings, can you explain what might be the cause?
  • Are there any follow-up tests that are warranted based on my renal panel test?
  • Should I take this test again? If so, when?

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