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Absolute Reticulocyte Count Calculator

Created by Małgorzata Koperska, MD
Reviewed by Bogna Szyk and Aleksandra Zając, MD
Last updated: Jan 18, 2024


The absolute reticulocyte count calculator estimates the number of reticulocytes in the patient's blood. The values needed for the calculation are the patient's reticulocyte percentage and hematocrit ratio.

In the advanced mode, there is also an option to input a desired normal hematocrit value. If you read on, you can learn what reticulocyte count is and how to estimate it.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. If any health condition bothers you, consult a physician.

What is reticulocyte count?

The absolute reticulocyte count is a quantitative measure of the bone marrow's production of new red blood cells. It's used as a marker of red cell production and helps distinguish hypo- and hyperproliferative anemias. The expected reticulocyte count in a healthy person is 26-130 cells/μL.

  • In an anemic patient, a higher than normal level of reticulocytes can indicate an appropriate elevation of red blood cell production as a reaction to the anemia. A very high number of reticulocytes in the blood can be described as reticulocytosis.

  • A low reticulocyte level informs us about a decreased bone marrow response. It can be induced by chemotherapy, aplastic anemia, pernicious anemia, bone marrow malignancies, problems with erythropoietin production, various vitamin or mineral deficiencies (iron, vitamin B12, folic acid), and chronic disease states (anemia of chronic disease).

In highly anemic patients, the result can be misleading. To better understand the patient's reticulocyte count, we advise you to use our corrected reticulocyte count calculator.

How to calculate the absolute reticulocyte count?

The equation is simple:

ARC = Reticulocytes × Hematocrit / normal_Hematocrit

It uses the percentage of reticulocytes among red blood cells and one's hematocrit (Hct). The normal_Hematocrit is a default value of 45%, but if you wish, change it to the desired value in the advanced mode. The calculated absolute reticulocyte count is expressed in cells per microliter (cells/μL).

🙋 You might also be interested in our other absolute blood count tools, such as the absolute neutrophil count calculator and a ANC calculator without bands. And there is also the absolute lymphocyte count calculator and the absolute eosinophil count calculator.

FAQ

What is absolute reticulocyte count used for?

The absolute reticulocyte count (ARC) test is performed to determine whether red blood cells are being formed in the bone marrow at the correct rate. When you determine the number of reticulocytes in the blood, you will get an indication of how quickly they are being produced and released by the bone marrow. A normal result for a healthy adult should be between 0.5 % and 2.5 % (or 26-130 cells/μL).

What does a high absolute reticulocyte count mean?

A higher than the normal number of reticulocytes (reticulocytosis) in your blood may mean that you have hemolytic anemia (a type of anemia), kidney cysts or tumors or your baby has hemolytic disease of the newborn. A reticulocyte count measures the number of reticulocytes (immature red blood cells) in the blood.

How can I calculate absolute reticulocyte count if reticulocytes are 12%?

Imagine that your dog has severe anemia with hematocrits of 15 % and reticulocytes of 12 %, then its ARC will be 4 cells/μLm.

  1. Use equation: ARC = Reticulocytes × Hematocrit / normal_Hematocrit.
  2. Insert the number of hematocrits (15%), reticulocytes (12 %), and normal (45%):
    ARC = 12% × 15% / 45% = 4 cells/μL.

Note that the hematocrit level is very low and reticulocytes are above interval, but the ARC rate suggests a mild regenerative response.

What is the difference between reticulocyte count and absolute reticulocyte count?

Reticulocyte count is a straight-up percentage of red cells that are reticulocytes. Absolute reticulocyte count will show you whether your body is producing enough reticulocytes in relation to your hematocrit level. When the hematocrit level falls, you should have correspondingly more reticulocytes (for example, you need significantly more reticulocytes at a hematocrit of 10% than at a hematocrit of 20%).

Małgorzata Koperska, MD
Hematocrit (Hct)
%
Reticulocytes
%
Absolute reticulocyte count
cells/μL
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