Reticulocyte Count
About Reticulocyte:
- Reticulocytes are immature red blood cells (RBCs) that are recently released from the bone marrow into the bloodstream.
- They still contain remnants of ribosomal RNA, which appear as a fine, reticular (mesh-like) network when stained with supravital stains like new methylene blue or brilliant cresyl blue.
Why Reticulocyte Count is Important?
- Reticulocyte count helps assess bone marrow function.
- It indicates the rate of RBC production.
- Used to monitor response to anemia treatment or bone marrow recovery.
Normal Reticulocyte Count
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Adults: 0.5 – 2.5% of RBCs
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Infants: 2 – 6%
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Absolute Reticulocyte Count (ARC): 25,000 – 75,000/µL
Clinical Significance or Indication
| Condition | Reticulocyte Count |
|---|---|
| 1. Iron deficiency anemia | Decreased or normal |
| 2. Hemolytic anemia | Increased |
| 3. Aplastic anemia | Decreased |
| 4. After blood loss or therapy | Increased (reticulocytosis) |
Types of Reticulocyte Count
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Relative Reticulocyte Count – % of total RBCs.
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Absolute Reticulocyte Count – Actual number per µL.
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Corrected Reticulocyte Count (CRC) – Adjusted for low hematocrit.
-
Reticulocyte Production Index (RPI) – Assesses bone marrow response in anemia.
Methods of Reticulocyte Count
1. Manual Method (Supravital Staining Method)
Principle:
When blood is mixed with a supravital stain (e.g., new methylene blue), reticulocytes precipitate their residual RNA as dark blue granules or network.
Requirements:
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Fresh EDTA blood sample
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Supravital stain (e.g., new methylene blue) – Brilliant Cresyl Blue Stain
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Microscope
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Slides and cover slips
Reagent Preparation:
Reagents Needed:
- Brilliant Cresyl Blue (BCB) – 1 g
- Sodium Citrate (Na₃C₆H₅O₇) – 0.7 g
- Sodium Chloride (NaCl) – 0.9 g
- Distilled Water – up to 100 mL
Procedure:
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Mix equal parts of blood and stain (usually 2–3 drops).
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Incubate at room temperature for 15–20 minutes.
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Prepare smears from the mixture.
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Allow them to air-dry.
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Examine under oil immersion (100x).
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Count reticulocytes among 1000 RBCs.
Calculation:
