Which hormone is primarily produced by the juxtaglomerular cells of the kidney?

The hormone primarily produced by the juxtaglomerular cells of the kidney is erythropoietin. These specialized cells are located in the kidney's juxtaglomerular apparatus, which plays a critical role in regulating blood pressure and the filtration rate. When oxygen levels in the blood are low, the juxtaglomerular cells release erythropoietin. This hormone stimulates the bone marrow to produce more red blood cells, which increases the blood's oxygen-carrying capacity and helps to restore normal oxygen levels.

Aldosterone, while related to kidney function, is produced in the adrenal cortex and is primarily involved in regulating sodium and potassium levels as well as blood pressure. Cortisol, another adrenal hormone, plays a role in metabolism and stress response but is not produced by the kidneys. Insulin, produced by the pancreas, regulates glucose levels in the blood. These hormones, although important, do not originate from the juxtaglomerular cells, rendering them unrelated to the specific activity of erythropoietin production.