Doctors may be missing early signs of kidney disease, according to a new study from Karolinska Institutet. Researchers found that even small changes in kidney function, falling within what is usually called the "normal" range, can signal future risks. To help, they created charts and an online tool to show how a person’s kidney function compares to others of the same age and sex. The study showed that people whose kidney function was in the bottom 25th percentile for their age group faced a much higher risk of kidney failure. It also pointed out that many of these patients do not get the follow-up tests needed to find early kidney damage.