What is the name of the blood test that counts the number of red blood cells?

The blood test that specifically counts the number of red blood cells is known as the erythrocyte count. This test provides essential information about a person's health, as red blood cells (erythrocytes) are crucial for transporting oxygen throughout the body and removing carbon dioxide.

The erythrocyte count can help diagnose conditions such as anemia, polycythemia, and other disorders affecting red blood cell production. While hematocrit measures the proportion of blood volume occupied by red blood cells, it does not directly count them; it reflects the concentration of red blood cells rather than the total number. The platelet count is unrelated to red blood cells, focusing instead on the number of platelets, which play a role in blood clotting. Red cell mass is a broader term that encompasses the total quantity of red blood cells but is not the specific test that counts them, making erythrocyte count the precise answer for measuring the number of red blood cells.