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Reticulocyte Count

Published: August 1, 2026Updated: August 1, 2026

A test that measures the number of immature red blood cells (reticulocytes) in your blood to evaluate bone marrow function and blood production.

Quick summary

["Measures immature red blood cells called reticulocytes","Helps diagnose and monitor anemia and bone marrow disorders","Evaluates how well your bone marrow is producing new red blood cells","Can differentiate between different types of anemia","Often performed alongside a complete blood count (CBC)"]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 1, 2026Editorial policy

Key facts at a glance

Category
hematology
Sample
whole-blood
Container
lavender-top (EDTA)
Fasting
false

What is a Reticulocyte Count?

A reticulocyte count is a blood test that measures the number of reticulocytes in your blood. Reticulocytes are immature red blood cells that are produced in the bone marrow and released into the bloodstream. They typically mature into fully developed red blood cells within 1-2 days. This test helps healthcare providers understand how well your bone marrow is working to produce new red blood cells, which is essential for transporting oxygen throughout your body.

What tests are included?

  • Reticulocyte count (absolute or percentage)
  • Reticulocyte production index (RPI) - adjusts for anemia severity and bone marrow maturation time
  • Often combined with Complete Blood Count (CBC) for comprehensive evaluation

When is this test needed?

Your healthcare provider may order a reticulocyte count when you have symptoms of anemia such as fatigue, weakness, shortness of breath, or pale skin. It is also used to monitor response to treatment for anemia, evaluate bone marrow function, diagnose conditions affecting red blood cell production, and assess recovery after chemotherapy or bone marrow transplant. Additionally, it helps differentiate between different causes of anemia - whether the bone marrow is producing too few cells (hypoproliferative) or if there is premature destruction of red blood cells (hemolytic).

Frequently asked questions

Is fasting required before a reticulocyte count?
No, fasting is typically not required for this test. You can eat and drink normally before the blood draw unless your healthcare provider instructs otherwise.
What does a high reticulocyte count mean?
A high reticulocyte count (reticulocytosis) indicates your bone marrow is producing more red blood cells than normal. This may occur due to recent blood loss, hemolytic anemia (where red blood cells are being destroyed), recovery from anemia treatment, or response to certain medications like erythropoietin.
What does a low reticulocyte count mean?
A low reticulocyte count (reticulocytopenia) suggests your bone marrow is not producing enough red blood cells. This may indicate bone marrow disorders, nutritional deficiencies (like iron, vitamin B12, or folate deficiency), chronic kidney disease, or certain infections or inflammatory conditions.
How is the reticulocyte count performed?
A healthcare professional will draw a small blood sample from a vein in your arm. The sample is then analyzed in a laboratory using automated blood analyzers or manual microscopic examination to count the reticulocytes.
  1. 1
    MedlinePlus - Reticulocyte CountSource
  2. 2
    Mayo Clinic - Reticulocyte CountSource
  3. 3
    American Family Physician - ReticulocytosisSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 1, 2026. · Read our editorial policy