Kidney function tests are important for diagnosing and managing kidney diseases. The tests can help determine how well the kidneys filter blood and remove waste, identify kidney problems early on, and guide treatment decisions. This comprehensive guide provides an overview of common kidney function tests, including what they measure, when they are used, and their costs.
Symptoms of Kidney Problems
If you have any of the following symptoms, you may have kidney problems:
- A sudden decrease in urine output
- Swelling in your legs, ankles, or feet
- Pain in your sides or back (under the ribs) that doesn’t go away
- Difficulty urinating
- Urine that smells bad or looks cloudy
- Blood in your urine
Types of Kidney Function Test
There are different kidney function tests, each of which assesses a different aspect of kidney function. The most common kidney function tests are:
- Urinalysis
A urinalysis is a test of your urine. It can show whether your kidneys leak abnormal amounts of protein or red blood cells into your urine. A urinalysis can also detect urinary tract infections, inflammation, and crystals in the urine that may cause kidney stones.
- Blood Urea Nitrogen (BUN) Test
The BUN gauges the amount of urea-derived nitrogen in the blood. Waste is generated from urea in the liver from the breakdown of amino acids. This test can help evaluate kidney function because urea is filtered out of the blood by the kidneys and then excreted in the urine.
- Serum Creatinine Test
The serum creatinine test is used to assess kidney function. The test measures the level of creatinine in your blood. Creatinine is a waste product that’s produced by your muscles and filtered out of your blood by your kidneys. A serum creatinine test is often used as part of a comprehensive metabolic panel (CMP) or basic metabolic panel (BMP) to help diagnose or monitor kidney disease.
- Estimated GFR
The estimated GFR (eGFR) tells you your stage of kidney disease and helps your healthcare professional plan your treatment. An eGFR test measures how well your kidneys work by calculating the creatinine level in your blood. Creatinine is a waste product that’s produced by muscle activity and filtered out of the blood by the kidneys. If your eGFR is low, it may be an early sign of kidney disease. A low eGFR can also be caused by other conditions, such as dehydration or heart failure.
How are the Tests Performed?
There are mainly two ways in which kidney function tests are performed:
Urine test
A urine test can show how well the kidneys are working. The creatinine level in the urine is determined by this test. Creatinine is an unwanted substance produced by muscle activity and filtered out by the kidneys.
Blood test
A blood test can measure levels of creatinine, BUN (blood urea nitrogen), and other substances in the blood that are signs of kidney function. The healthcare provider may also order tests to measure electrolyte levels, which can be affected by kidney problems.
The Bottom Line
Kidney function tests are an important part of keeping your kidneys healthy. By understanding what these tests entail and what they can tell you about your kidney health, you can get the most out of them. We hope this guide was helpful.