Reticulocytes (%)

Your bone marrow constantly creates new red blood cells as your body needs them. A reticulocyte count checks to see if your bone marrow is making the right amount of red blood cells when old ones die off. If you have too few, your tissues may not get enough oxygen. If you have too many, you could be at risk for blood clots or other health concerns. This test can check for certain health conditions or show how well a treatment is working.

If the reticulocyte count is too high or too low, it can be a sign of a serious health condition, including anemia and conditions of the bone marrow, liver, and kidneys.

To understand the results of a reticulocyte count test, your provider will consider your symptoms, medical history, and the results of other blood tests.

A higher-than-normal reticulocyte percentage usually means the bone marrow is making more red blood cells than usual, such as after blood loss, after starting treatment for iron or vitamin deficiency, or in hemolytic anemia (where red cells are being destroyed faster than usual).

A lower-than-normal reticulocyte percentage usually means the bone marrow is not making enough red blood cells. Causes include iron, vitamin B12, or folate deficiency, bone marrow problems, kidney disease, chronic illness, and treatments such as chemotherapy or radiation.

An early rise in reticulocytes (within several days) is one of the first signs that treatment for a nutritional anemia is working.

If your reticulocyte test results were not normal, it doesn't always mean you have anemia or another health condition. Other factors, such as recent treatment, pregnancy, or living at a high altitude, can also affect your results.