Kidneys clean the blood and rid the body of waste products. Healthy kidneys function at 100%, but many medical conditions can lead to a loss of function. Once function drops below 15%, a person may need dialysis (a process to clean the blood) or a kidney transplant. Kidney function is estimated by blood tests.
Whether kidney function can improve depends on how quickly the kidney became damaged and the reasons they were injured.
Some diseases that cause rapid damage can be treated, but in most cases, kidney function will not return to 100%. If the kidney damage occurred over a longer time period (from months to years), the possibility of significantly improving the function of the kidneys is much less likely.