What hormones are produced by the kidneys?

The kidneys are best known for filtering blood and making urine, but they also serve as important hormone-producing organs. These hormones are chemical messengers that help control essential body functions beyond the urinary system.

One of the most important hormones made by the kidneys is erythropoietin (often shortened to EPO). This hormone tells your bone marrow to produce red blood cells. When oxygen levels in your blood drop—such as at high altitude or due to illness—your kidneys release more erythropoietin to help increase the number of red blood cells and improve oxygen delivery throughout the body.

Another key hormone is renin, which helps regulate blood pressure. When blood pressure drops too low, the kidneys release renin into the bloodstream. This triggers a chain reaction called the renin-angiotensin-aldosterone system (RAAS). It causes blood vessels to narrow and helps the body retain salt and water, both of which raise blood pressure to a safer level.

The kidneys are also involved in producing calcitriol, the active form of vitamin D. This hormone plays a major role in maintaining healthy bones by helping your body absorb calcium from food. Without enough calcitriol, even a calcium-rich diet will not benefit your bones the way it should.

These kidney-produced hormones are essential for maintaining balance in the body. They support red blood cell production, stabilize blood pressure, and ensure that bones remain strong and healthy.

When the kidneys are not functioning well, hormone production can be affected, leading to anemia, bone problems, and blood pressure issues. This shows just how important the kidneys are—not just for removing waste, but for overall health.

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