Know Your Body: Why do your kidneys make urine — and what else do they do?
No. Your kidneys make urine, but that is only one result of their bigger job: carefully sorting your blood.
Filtering blood, all day
You have two kidneys. Blood flows through them, where wastes and extra water are removed. This leftover fluid becomes urine and travels to the bladder.
Your kidneys do not simply throw away everything that passes through them. They return most of the water and useful substances your body still needs back to the blood.
This helps keep the right balance of water, salts and minerals in your blood. They also help balance acid. These jobs support normal work throughout the body.
More than a urine-making system
Your kidneys also make hormones. These are chemical messengers that help control blood pressure, help the body make red blood cells and help keep bones healthy.
You can think of the kidneys like a careful filtering and sorting system. They separate what needs to leave from what the body should keep. This is only a simple comparison, because the real process is very detailed.
One useful thing to remember
Urine is one result of the kidneys’ work. Their bigger everyday role is sorting the blood and helping keep its contents in balance.
Read more from Your Kidneys & How They Work - NIDDK.
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This article is for general education and does not replace personalised advice from a qualified healthcare professional.