A new kidney disease test could alert people with chronic kidney disease that they’re at high risk for kidney disease complications. According to a study from the University of California at San Francisco, a new test called the cystatin c test provides valuable information doctors can use to determine a patient’s risk for developing kidney disease complications.
Conventionally, doctors have looked at measurements of creatinine, a by-product of muscle breakdown, to assess kidney function. When the kidneys aren’t functioning properly, creatinine isn’t filtered as well by the kidneys, and creatinine levels rise in the bloodstream. The new cystatin c test has advantages over the conventional method of measuring creatinine levels, and it may ultimately prove to be a better test for diagnosing and following chronic kidney disease.
What is Cystatin C?
Cystatin c is a protein made by cells that filters through the kidneys into the urine. Like creatinine, levels of cystatin c rise in the bloodstream when the kidneys lose their ability to filter it into the urine. Unlike creatinine, it’s not just found in muscle tissue, but in all cells in the body. This makes it a more reliable test since creatinine levels in the blood are higher in people with more muscle mass, which can skew the results.
Creatinine levels can also be affected by diet and may be slightly higher in people who eat a lot of meat. It may also be less accurate in people who are obese or have severe liver disease. Measuring cystatin c levels circumvents these problems since it doesn’t vary with muscle or mass or diet and is a more reliable indicator of kidney function.
Comparing These Two Kidney Disease Tests
When researchers compared these two kidney tests, only those with abnormal cystatin c levels had a greater risk of kidney disease complications. People with high creatinine c levels but normal cystatin c were not at greater risk of dying of a heart attack, stroke or kidney failure as a result of their kidney disease.
In addition, the cystatin C test was able to identify people with chronic kidney disease who would have been missed using the more conventional creatinine test.
The Bottom Line?
Right now, doctors are only using the cystatin c kidney disease test in cases where creatinine measurements could be inaccurate or when they’re not providing enough information. But cystatin c tests are likely to be used more in the future as studies show it’s a better test for predicting kidney disease complications, and, possibly, a better test for early diagnosis.
Eurekalert.org. “New Test Can Predict Complications From Kidney Disease”