Your kidneys have the very important job of filtering your blood and helping your body rid itself of waste. They usually come in pairs of two, but people sometimes end up with only one that functions properly. Why? Well, it depends. You can end up living with one kidney if:

You donated a kidney.

You had one removed because of chronic kidney disease (CKD), injury or cancer.

You were born with two, but only one was functional at birth.

You were born with two, but one stopped functioning later in life because of damage resulting from conditions like a ureteral obstruction or renal artery stenosis (lack of blood flow).

Can you survive with one kidney? If so, what will life be like once you’ve lost such an important organ?

Nephrologist and kidney medicine specialist James Simon, MD, answers these questions and provides advice for how to protect the kidney you have left.

If you have one kidney, you can live a long, healthy life depending on a variety of factors like age, any underlying conditions and the overall health of your kidneys at the time one is lost.

“The healthier and younger the kidney is, the more it can grow and take up a lot of the slack,” says Dr. Simon. “Typically, someone’s kidney function may drop a little bit, but still stay within the normal range, and those people can live fine for the rest of their lives with just one kidney.”