To help diagnose and manage conditions affecting kidney function; may be used as part of general health screening or to screen someone who is at risk of developing kidney disease, or to follow someone with known kidney disease
A blood sample drawn from a vein in your arm
You may be instructed to fast for 8-12 hours (no food, only water) prior to the test.
A renal panel is a group of tests that may be performed together to evaluate kidney (renal) function. The tests measure levels of various substances, including several minerals, electrolytes, proteins, and glucose (sugar), in the blood to determine the current health of your kidneys.
The kidneys are a pair of bean-shaped organs located at the bottom of the ribcage to the right and left of the spine. They are part of the urinary tract and perform a few essential roles and functions within the body.
- Within the kidneys are about a million tiny blood filtering units called nephrons. In each nephron, blood is continually filtered through a cluster of looping blood vessels, called a glomerulus, which allows the passage of water and small molecules but retains blood cells, proteins such as albumin, and larger molecules.
- Attached to each glomerulus are tubes (tubules) that have a number of sections that collect the fluid and molecules that pass through the glomerulus, reabsorb what can be re-used by the body, add other molecules through a process called secretion and, finally, adjust the amount of water that is eventually eliminated along with the waste as urine.
- Besides eliminating wastes and helping to regulate the amount of water in the body, these activities allow the kidneys to maintain normal chemical balance in the body. Among the important substances the kidneys help to regulate are sodium, potassium, chloride, bicarbonate, calcium, phosphorus, and magnesium. The right balance of these substances is critical. When the kidneys are not working properly, the concentrations of these substances in the blood may be abnormal and waste products and fluid may build up to dangerous levels in the blood, creating a life-threatening situation.
- Kidneys also have a number of other miscellaneous roles in maintaining a healthy body, including the production of a hormone that stimulates red blood cell production (called erythropoietin), production of a hormone that helps maintain a normal blood pressure (called renin), and turning one form of vitamin D into a more active form, which enhances calcium absorption.
If the kidneys are not functioning properly, waste products can accumulate in the blood and fluid levels can increase to dangerous volumes, causing damage to the body or a potentially life-threatening situation. Numerous conditions and diseases can result in damage to the kidneys. The most common causes of and main risk factors for kidney disease are diabetes and hypertension. For more on the types and causes, see the article on Kidney Disease.
The individual tests included in a renal panel can vary by laboratory, but the tests typically performed include:
Electrolytes – electrically charged chemicals that are vital to normal body processes, such as nerve and muscle function; among other things, they help regulate the amount of fluid in the body and maintain the acid-base balance. Electrolytes include:
- Phosphorus – a mineral that is vital for energy production, muscle and nerve function, and bone growth; it also plays an important role as a buffer, helping to maintain the body's acid-base balance.
- Calcium – one of the most important minerals in the body; it essential for the proper functioning of muscles, nerves, and the heart and is required in blood clotting and in the formation of bones.
- Albumin – a protein that makes up about 60% of protein in the blood and has many roles such as keeping fluid from leaking out of blood vessels and transporting hormones, vitamins, drugs, and ions like calcium throughout the body.
- Urea/Blood Urea Nitrogen (BUN) – urea is a nitrogen-containing waste product that forms from the metabolism of protein; it is released by the liver into the blood and is carried to the kidneys, where it is filtered out of the blood and eliminated in the urine.
- Creatinine – another waste product that is produced by the body's muscles; almost all creatinine is eliminated by the kidneys.
- Glucose – supplies energy for the body; a steady amount must be available for use, and a relatively constant level of glucose must be maintained in the blood.
Three calculated values may also be reported with a renal panel:
- Urea (BUN)/Creatinine Ratio – a comparison of urea (nitrogen) to creatinine content in the blood
- Estimated Glomerular Filtration Rate (eGFR) – a calculated estimate of the actual glomerular filtration rate (GFR, the amount of blood filtered by the glomeruli in the kidneys per minute) derived from creatinine levels in the blood; the formula takes into account the person's age, gender, race, and sometimes height and weight.
- Anion Gap – anion gap (AG or AGAP) is a value calculated using the results of an electrolyte panel. It evaluates the difference between measured and unmeasured electrical particles (ions or electrolytes) in the fluid portion of the blood.
How is the test used?
A renal panel may be used to evaluate kidney function, to help diagnose kidney-related disorders, to screen those who may be at risk of developing kidney disease or to monitor someone who has been diagnosed with kidney disease.
When is it ordered?
A healthcare practitioner may order a renal panel when someone has risk factors for kidney dysfunction such as high blood pressure (hypertension), diabetes, cardiovascular disease, obesity, elevated cholesterol, or a family history of kidney disease.
A healthcare practitioner may order a renal panel when someone has signs and symptoms of kidney disease, though early kidney disease often does not cause any noticeable symptoms. It may be initially detected through routine blood or urine testing. Examples of some signs and symptoms include:
- Swelling or puffiness, especially around the eyes or in the face, wrists, stomach, thighs or ankles
- Urine that is foamy, bloody, or coffee-colored
- A decrease in the amount of urine
- Problems urinating, such as a burning feeling or abnormal discharge during urination, or a change in the frequency of urination, especially at night
- Mid-back pain, below the ribs, near where the kidneys are located
A renal panel may also be ordered at regular intervals when someone is being treated for kidney disease for monitoring purposes.
What does the test result mean?
Renal panel test results are not diagnostic but rather indicate that there may be a problem with the kidneys and that further testing is required to make a diagnosis and determine the cause. Results of the panel are usually considered together, rather than separately. Individual test result can be abnormal due to causes other than kidney disease, but taken together with risks and/or signs and symptoms, they may give an indication of whether kidney disease is present.
See the articles on the individual tests for more detailed information about each one:
One of the results from my renal panel is slightly out of range. What does this mean?
The results of your renal panel are interpreted by your healthcare provider within the context of other tests that you have had done as well as other factors, such as your medical history. A single result that is slightly high or low may or may not have medical significance. There are several reasons why a test result may differ on different days and why it may fall outside a designated reference range.
- Biological variability (different results in the same person at different times): If a healthcare practitioner runs the same test on you on several different occasions, there's a good chance that one result will fall outside a reference range even though you are in good health. For biological reasons, your values can vary from day to day.
- Individual variability (differences in results between different people): Reference ranges are usually established by collecting results from a large population and determining from the data an expected average (mean) result and expected differences from that average (standard deviation). There are individuals who are healthy but whose tests results, which are normal for them, do not always fall within the expected range of the overall population.
Thus, a test value that falls outside of the established reference range supplied by the laboratory may mean nothing significant. Generally, this is the case when the test value is only slightly higher or lower than the reference range and this is why a healthcare practitioner may repeat a test on you and may look at results from prior times when you had the same test performed.
However, a result outside the range may indicate a problem and warrant further investigation. Your healthcare provider will evaluate your test results in the context of your medical history, physical examination, and other relevant factors to determine whether a result that falls outside of the reference range means something significant for you.
Will these tests always be run as a panel?
No, each test that is usually included in a renal panel may be run independently or along with different tests, depending on the purpose of the testing. For example, the electrolytes (sodium, potassium, chloride, and bicarbonate) may be run as an electrolyte panel as part of a routine health screen or to detect a potential problem with someone's fluid or acid-base balance, which could be caused by heart disease, for example. The glucose test is also commonly performed to screen for, diagnose, and monitor diabetes.
What other tests besides those included in a renal panel might be ordered to assess kidney function?
Other laboratory tests that can be used to assess kidney function include:
For people with diabetes or high blood pressure (hypertension), a urine albumin (microalbumin) test, which measures small amounts of albumin leakage from the blood into the urine, may also be used to detect early kidney damage. When both albumin and creatinine are measured in a random urine sample, an albumin/creatinine ratio (ACR) can be calculated. This may be done to more accurately determine how much albumin is escaping from the kidneys into the urine.
The National Kidney Foundation (NKF) and the National Kidney Disease Education Program (NKEDP) recommend two tests, in addition to blood pressure measurement, to screen for kidney disease in people with increased risk: urine protein (either urine albumin, urinalysis or urine total protein) and estimated glomerular filtration rate (eGFR).
When a structural problem is suspected, a variety of imaging tests can be used to evaluate the kidneys. A sample of kidney tissue, a biopsy, is sometimes helpful in diagnosing the specific cause of the problem. For more information, see the article on Kidney Disease.
Can I have kidney disease if I feel fine?
Yes. Kidney disease often does not cause noticeable symptoms until late in the disease. That is why it is important, especially for those with risk factors for kidney disease, to have regular health exams so that any disorders or diseases that may affect the kidneys can be promptly addressed.
Can I have abnormal test results and not have kidney disease?
Yes. Since the tests included in the renal panel can have broad applications, abnormal results on one or more of the tests could indicate a problem other than kidney disease. Your healthcare provider will interpret the results of your renal panel tests by looking at all of your results, along with the results of any other tests you had performed as well as your symptoms, exam findings, and medical and family history.