More than 37 million Americans are estimated to have kidney disease, with many more at risk of developing kidney disease. Chronic kidney disease (CKD) is a condition characterized by the kidneys no longer being able to filter blood as they should due to damage. Symptoms of kidney damage generally do not present until your kidneys are badly damaged. This late presentation results in many people not knowing they have CKD or end-stage renal disease (ESRD) until it is too late to start preventative measures.
When preventative measures and treatment are started early in kidney disease, the progression of CKD can often be slowed, and other health conditions may be prevented entirely. However, not all people with kidney disease progress to complete kidney failure. Getting your kidney function regularly tested is recommended to help prevent CKD and lower the risk of developing kidney disease.
- Proper kidney function is essential for maintaining good health.
- Testing kidney function is typically the only way to establish how well your kidneys are working.
- Urine and blood tests are the two most common ways kidney function is checked.
Kidney Function Overview
The kidneys are two-bean-shaped organs that makeup part of the urinary system. They are located in the back of the abdomen, one on each part of the spine, just below the ribcage. The kidneys help the body to remove waste materials by filtering, on average, half a cup of blood every minute. This filtration of blood removes extra water and waste, producing urine, which is moved into the bladder through the ureters.
The kidneys also remove an acid that is produced in the process of homeostasis in your blood. Without the balance of water, salts, and minerals, the body’s muscles, nerves, and tissues cannot function correctly. Your kidneys produce hormones that control blood pressure, maintain strong and healthy bones, and make red blood cells.
Each kidney is made up of roughly a million filtering units called nephrons, with each nephron containing a filter called the glomerulus and a tubule. The nephrons work in a two-step process: first, the glomerulus filters the blood, and second, the tubule then returns the essential substances back to your blood, removing the waste products.
When do I need a kidney function test?
Some diseases and conditions, such as hypertension (high blood pressure) or diabetes, negatively affect how well the kidneys are able to function. Your healthcare provider may monitor these conditions by using kidney function tests.
It is important to get your kidney function tested if you have the following:
- A family history of kidney failure
- Heart disease
- Frequent need or urge to urinate
- Dysuria (painful urination)
- Hypertension (high blood pressure)
- Hematuria (blood in your urine)
How Kidney Function is Tested
If your healthcare provider requires your kidney function to be tested, they will either use a blood test to check how well your kidneys are filtering blood or a urine test to check for albumin levels.
When the kidneys are damaged, the protein albumin (that is found in the blood) passes into the urine. This is known as albuminuria. Healthy functioning kidneys do not let albumin pass into the urine, therefore the less albumin that is present in the urine, the better your kidney function. Your healthcare provider can check albumin levels in your urine in two ways.
- Dipstick urine test. A urine sample is collected at your healthcare provider’s office or lab. A dipstick (strip of chemically treated paper) is placed into the container of urine by the healthcare provider. The dipstick will change color if there is albumin present in your urine.
- Urine albumin-to-creatinine ratio (UACR). This urine test measures and compares the amount of creatine with the amount of albumin in the urine sample. This comparison is used to estimate how much albumin is passing into your urine over a 24-hour period. A urine albumin result of more than 30mg/g may be an indication of kidney disease. A result of 30mg/g or less is a normal test result.
If your results show that you have albumin in your urine, your healthcare provider may repeat the urine tests a couple of times to definitively confirm the results. Your healthcare provider will then talk to you about the next steps and what your results mean.
During kidney disease treatment, urine albumin tests may help your provider determine which treatments work best for you. During treatment, if your urine albumin levels remain the same or drop, this indicates that the treatment is working.
Blood tests indicate how well your kidneys work and how quickly they remove waste products. Blood tests that are used to test kidney function include:
- A serum creatinine blood test. This test measures the amount of creatinine present in your blood. The levels of creatinine increase if your kidneys are not functioning correctly. Normal creatinine levels depend on age, sex, and muscle mass of each individual.
- Glomerular filtration rate (GFR). GFR is a measure of how well the kidneys are able to remove toxins, waste, and extra fluid from the blood. GFR is calculated using your serum creatinine level, sex, and age. Your kidney’s function is not what it should be if your GFR is low. As kidney disease progresses, the lower your GFR will be.
- Blood urethra nitrogen (BUN). This test measures the amount of urea nitrogen (a waste product) in your blood. Urea nitrogen is a waste product that is produced when your body breaks down protein food in the food you eat. When your kidneys are healthy and functioning properly, urea nitrogen is filtered out of your blood and passes out the body through your urine. If your levels of BUN are higher than the normal range (based on age and health conditions), it may indicate that your kidneys are not working as they should. As kidney disease progresses, a higher level of BUN is present.
Your healthcare provider may want to conduct other tests, such as monitoring blood pressure, ordering imaging, or scheduling a biopsy to check the functioning of your kidneys.
- Blood pressure. Hypertension or high blood pressure is one of the most common causes of chronic kidney disease and kidney failure. Therefore your healthcare provider will want to monitor your blood pressure to ensure that it is being managed.
- Medical imaging. Healthcare providers use imaging such as CT scans and ultrasounds to get a better image of kidney damage and check if there is a narrowing or blockage in the blood vessels.
- Kidney biopsy. In this procedure, a small piece of the kidney is removed and examined for signs of disease or damage. A kidney biopsy is performed by inserting a thin needle through the skin.
If you have already been diagnosed with kidney disease, both blood tests and urine tests are used to monitor your disease progression and ensure that your treatment plan is working.
How Often Should Kidney Function be Checked?
Getting your kidney function tested is relatively easy, non-invasive, and critical for seeking a diagnosis or monitoring current treatment plans. Many recommended getting your kidneys checked annually if you have diabetes. Consult with your healthcare provider if you have hypertension, a history of kidney failure, or heart disease, as they will recommend how often your kidney function should be tested.
If CKD is suspected, the sooner a diagnosis is confirmed, the earlier effective treatment plans can be implemented to help slow disease progression and preserve kidney function.
How Panoramic Health Supports You Through Your Kidney Care Journey
Patients that have been diagnosed with CKD or ESRD have complex needs and require a holistic care team to support them. Panoramic Health and its Circle of Care team work with nephrologists and patients across the country to develop individualized holistic treatment plans, providing comprehensive care throughout the kidney disease journey.
Led by physicians, Panoramic Health is one of the largest integrated value-based kidney care platforms led by physicians, with a network of 800+ healthcare providers across 19 states. This provides patients with treatment options, such as at-home dialysis and around-the-clock access to a care team.