ATI TEAS (Test of Essential Academic Skills) Version 7ScienceHard

A patient is diagnosed with a condition affecting the production of red blood cells. The physician explains that a hormone produced primarily by the kidneys plays a crucial role in stimulating this process. Which hormone is being referred to?

  1. AAldosterone
  2. BErythropoietin
  3. CRenin
  4. DCalcitriol
Show answer & explanation

Correct answer: B. Erythropoietin

Erythropoietin (EPO) is a hormone primarily produced by the kidneys in response to hypoxia (low oxygen levels). It stimulates the bone marrow to produce red blood cells (erythropoiesis), thus increasing the oxygen-carrying capacity of the blood.

Why the other options are wrong

  • A. Aldosterone is a hormone produced by the adrenal glands that regulates sodium and potassium balance, not red blood cell production.
  • C. Renin is an enzyme produced by the kidneys that regulates blood pressure, not red blood cell production.
  • D. Calcitriol (active vitamin D) is involved in calcium and phosphate absorption, influenced by the kidneys but not directly stimulating RBC production.

Erythropoietin (EPO)

A hormone produced primarily by the kidneys that stimulates the production of red blood cells (erythropoiesis) in the bone marrow.

  • Released in response to hypoxia.
  • Increases oxygen-carrying capacity of blood.
  • Used clinically to treat anemia.

Memory trick: EPO makes 'red' cells 'grow'.

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