Final answer:
Erythropoietin (EPO) is a hormone secreted by the kidneys to stimulate red blood cell production in response to low oxygen levels. It plays a key role in regulating the oxygen capacity of the blood but can lead to health risks if used improperly for performance enhancement.
Step-by-step explanation:
The kidneys are vital organs with not only excretory functions but also hormonal roles. Among the hormones they release is erythropoietin (EPO), which is crucial for the production of red blood cells. EPO is secreted in response to low oxygen levels in the blood, signaling the bone marrow to increase erythropoiesis. This process is essential for maintaining the oxygen-carrying capacity of the blood, especially under conditions causing hypoxemia.
Apart from EPO, the kidneys secrete other hormones such as renin, which is involved in regulating blood pressure, and calcitriol, the active form of vitamin D, important in calcium homeostasis. EPO is also noted for its misuse as a performance-enhancing drug in sports, known as blood doping, which can lead to health complications like increased blood viscosity and heightened risk of thrombotic events.
Understanding the role of kidney hormones is significant in the context of diseases like chronic kidney disease (CKD), where their functions may be compromised leading to anemia and bone metabolism disorders among other complications.