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Hormones in Urinary System, Role of Hormones in Urinary System

Role of Hormones in Urinary System

Hormones in Urinary system is that the kidneys produce and interact with several hormones that are involved in the control of systems outside of the urinary system.

Role of Hormones in Urinary System


EPO is a 193-amino acid protein which  stimulates the formation of red blood cells in the bone marrow. The kidney produces 85 percent of circulating EPO; and remaining 15 percent in the liver.

Erythropoietin, also known as EPO, is a hormone which is produced by the kidneys to stimulate the production of red blood cells.

The kidneys monitor the condition of the blood that passes through their capillaries, including the oxygen-carrying capacity of the blood. When the blood becomes hypoxic, which mean carrying low level of oxygen, cells lining the capillaries begin producing EPO and release it into the bloodstream.

EPO travels through the blood to the red bone marrow, where it stimulates hematopoietic cells to increase their rate of red blood cell production.

Red blood cells contain hemoglobin, which increases the blood’s oxygen-carrying capacity and which helps to ends the hypoxic conditions.

If you move to a higher altitude, the partial pressure of oxygen is lower, and because of that there is less pressure to push oxygen across the alveolar membrane and into the red blood cell.

If you start an aerobic exercise, your tissues will need more oxygen to cope with situation, and the kidney will produce more EPO. If erythrocytes are lost due to severe or prolonged bleeding, or under produced due to disease or severe malnutrition, the kidneys come to the rescue by producing more EPO.

Renal failure (loss of EPO production) is associated with anemia, which makes it difficult for the body to cope with increased oxygen demands or to supply oxygen adequately even under normal conditions. In this cases EPO supplement to be given to the person.


Calcitriol is the active form of vitamin D in the human body. It is produced by the kidneys from precursor molecules produced by UV radiation striking the skin.

Calcitriol works together with parathyroid hormone (PTH), it helps to raise the level of calcium ions in the bloodstream. When the level of calcium ions in the bloodstream drops below a threshold level, the parathyroid glands release PTH, which in turn stimulates the kidneys to release calcitriol.

Calcitriol promotes the small intestine to absorb calcium from food and deposit it into the bloodstream. It also stimulates the osteoclasts of the skeletal system to break down bone matrix to release calcium ions into the blood.


Renin is not a hormone itself, but an enzyme that the kidneys produce to start the renin-angiotensin system (RAS). The RAS increases blood volume and blood pressure in response to low blood pressure, blood loss, or dehydration.

Renin is released into the blood where it catalyzes angiotensinogen from the liver into angiotensin I. Angiotensin I is further catalyzed by another enzyme into Angiotensin II.

Angiotensin II stimulates several processes, including stimulating the adrenal cortex to produce the hormone aldosterone.

Aldosterone use changes the function of the kidneys to increase the reabsorption of water and sodium ions into the blood, increasing blood volume and raising blood pressure.

Negative feedback from increased blood pressure finally turns off the RAS to maintain healthy blood pressure levels.