Certified Dialysis Nurse Practice Test 2025 - Free Dialysis Nurse Practice Questions and Study Guide

The hormone produced by the kidney in response to low oxygen levels is erythropoietin. This hormone plays a crucial role in the regulation of red blood cell production in the bone marrow. When there is a decrease in oxygen levels, such as during anemia or at high altitudes, the kidneys detect this change and release erythropoietin to stimulate the production of more red blood cells, thus improving the oxygen-carrying capacity of the blood.

Calcitriol, though important for calcium and phosphate metabolism, is primarily produced in response to low levels of calcium and does not directly respond to oxygen levels. Aldosterone is involved in the regulation of sodium and potassium levels and is primarily influenced by the renin-angiotensin-aldosterone system rather than oxygen levels. Parathyroid hormone is secreted by the parathyroid glands in response to low blood calcium levels, making it unrelated to oxygen sensing.

In summary, erythropoietin is specifically linked to oxygen levels and is essential for ensuring adequate oxygen delivery in the body, which is why it is the correct answer.