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Hematology: reticulocyte count
Overview
- Immature form of RBC normally only present in bone marrow or in peripheral blood in low numbers.
- Released into circulation when increased demand.
- Reticulocytes appear in the blood 2-4 days after sudden blood loss. Therefore repeat sampling may be necessary.
- To determine if anemia is regenerative or non-regenerative.
- Other reticulocyte calculations are the absolute reticulocyte count and the reticulocyte production index (RPI).
- Reticulocytes are best identified on supravital stains, eg new methylene blue stain.
This may not be done routinely unless requested. - Polychromatophilic cells with Romanowsky stains are reticulocytes, but may underestimate response based on polychromasia alone.
Uses
In combination
- Hemolytic Anemia: immune mediated hemolytic or hemorrhagic anemia Anemia: blood loss - in combination with other RBC parameters, eg PCV Hematology: packed cell volume , MCV Hematology: mean corpuscular volume , MCHC Hematology: mean corpuscular hemoglobin concentration.
- Persistent hemorrhage - in combination with thrombocytosis Hematology: platelet count , low plasma protein Blood biochemistry: total protein , hypochromasia and microcytosis.
- Suspected lead poisoning Lead toxicity.
- Hereditary disorders, eg Grey Collie syndrome Cyclic hematopoiesis , pyruvate kinase deficiencies, stomatocytosis. Reticulocytosis seen with a number of other hematological abnormalities.
- Chronic lung disease - poor oxygenation will result in reticulocytosis without anemia (perceived hypoxia).
- Hypoproliferative or non-regenerative anemia - reticulocytosis may be seen but is of insufficient magnitude for the anemia, eg iron deficiency, liver disease.
Other points
- Reticulocytosis is seen in late pregnancy and newborn puppies (adult levels reached at 2-3 months of age).
Sampling
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Tests
Methodologies
- Cytological examination of supravitally stained blood smear.
Availability
- Widely available at commercial laboratories.
Validity
Sensitivity
- Moderate to high.
Specificity
- Low.
Technique intrinsic limitations
- Periodic filtering of NMB stain required to prevent precipitation that may be confused with reticulocytes.
Technician extrinsic limitations
- Requires some experience for accurate identification of all reticulocytes.
Result Data
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Further Reading
Publications
Refereed papers
- Recent references from VetMedResource and PubMed.
- Evans G O et al (1994) Reticulocyte counts in canine and rat blood made by flow cytometry. J Comp Pathol 111 (1), 107-111.
- Onishi T et al (1994) Changes of serum hemolytic activity and the number of reticulocytes in canine Babesia gibsoni infection. J Vet Med Sci 56 (3), 611-612.
Other sources of information
- Cowell R J, Tyler R D & Meinkoth J H (1999) Diagnostic Cytology and Hematology of the Dog and Cat. 2nd edn. Mosby, USA.
- Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, USA.
- Jain N C (1993) Essentials of Veterinary Hematology. Lea & Febiger, USA.