Your kidneys work quietly in the background every day, doing jobs that are vital for your health. These two bean-shaped organs filter your blood, remove waste and extra fluid, help control blood pressure, and keep the balance of important minerals like sodium and potassium just right.
Because they are so important, it’s a good idea to keep track of how well they’re working. That’s where kidney function tests come in.
Kidney function tests are simple medical tests that help doctors check if your kidneys are doing their job properly. These tests can show early signs of kidney problems even before you notice any symptoms, which is why they are often part of routine check-ups—especially for people at risk of kidney disease.
One of the common tests is the Blood Urea Nitrogen (BUN) test. Urea is a waste product that your body makes when it breaks down protein from food. Your kidneys filter this waste out through your urine. If the kidneys aren’t working well, urea builds up in the blood.
The BUN test measures how much of this urea nitrogen is in your blood. A normal BUN level is usually between 7 and 20 milligrams per deciliter (mg/dL), but it may vary depending on your age and the lab doing the test.
Another important test is the Serum Creatinine test. Creatinine is a waste product made by your muscles during everyday activities. Healthy kidneys remove creatinine from your blood.
If your kidneys are not filtering properly, the level of creatinine in your blood will rise. For men, normal creatinine levels are around 0.6 to 1.2 mg/dL, and for women, it’s about 0.5 to 1.1 mg/dL. People with more muscle may have slightly higher levels.
To get a fuller picture of kidney health, doctors often look at the Glomerular Filtration Rate (GFR). This is not a direct test but a calculation based on your creatinine levels, age, gender, and body size. It estimates how much blood your kidneys filter each minute.
A GFR of 60 or higher is considered normal. If it drops below 60, it may mean you have kidney disease. If it falls to 15 or lower, it could be a sign of kidney failure, which means your kidneys are struggling to work at all.
Urine tests are also useful in checking kidney function. A Urinalysis looks at the appearance and content of your urine. It can detect things like protein or blood, which shouldn’t normally be there. Protein in the urine, for example, might mean the kidneys’ filters are damaged.
Another helpful urine test is the Albumin-to-Creatinine Ratio (ACR). This test checks how much of a protein called albumin is in your urine compared to the level of creatinine. Even small amounts of albumin can be an early sign of kidney damage, especially in people with conditions like diabetes or high blood pressure.
If you have diabetes, high blood pressure, or a family history of kidney problems, these tests are especially important. You might not feel any different when your kidneys start to struggle, which is why early testing and regular check-ups can make a big difference.
It’s also worth remembering that one unusual test result doesn’t always mean something serious. Sometimes, results can be affected by things like what you’ve eaten or how much water you’ve had. But if test results are not in the normal range, it’s a sign to look more closely and possibly repeat the test or do further checks.
In short, kidney function tests are a smart way to keep track of your health. They help catch problems early—before they become serious—and give you and your doctor the information needed to take action. By staying informed and asking your doctor about these tests, you can take steps to protect your kidneys and your overall health.
If you care about kidney health, please read studies about pesticide linked to chronic kidney disease, and this drug may prevent kidney failure in people with diabetes.
For more health information, please see recent studies about drug duo that may treat kidney failure, and results showing these vegetables may protect against kidney damage.
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