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Absolute Reticulocyte Count & Reticulocyte Index

Calculators  Hematology
The absolute reticulocyte count indicates the rate of erythropoiesis. The reticulocyte index determines if the reticulocyte count is appropriate for the level of anemia.
Reticulocyte count
%
Hematocrit value
%
Normal Hematocrit value
based on age/gender
%
Result:

Background

Measured Factor
Absolute reticulocyte count and Reticulocyte index
Measured Factor Disease
  • Aplastic anemia
  • Megaloblastic anemia
  • Hypoproliferation to anemia
  • Iron deficiency anemia
  • Folic acid deficiency
  • Vitamin B-12 deficiency
  • Polycythemia vera
  • Heart disease
  • Leukemia
  • Lymphoid neoplasms
  • Metastasis
  • Sepsis
  • Malaria
  • Hyperproliferation to anemia
  • Hemolytic anemia
  • Blood loss
Measured Factor Detail
Reticulocytes are immature red blood cells. The reticulocyte count estimates the rate of erythropoiesis without the need for bone marrow aspiration. If anemia is present, the reticulocyte count is high and thus may not reflect true bone marrow responses to anemia. Therefore, in anemia cases, the reticulocyte count is adjusted based on hematocrit and is called absolute reticulocyte count.

The reticulocyte index corrects for the premature release of reticulocytes from bone marrow using maturation time of reticulocytes. Reticulocyte index assess the level of bone marrow response to anemia.
Speciality
Multi-Speciality
Body System
Hematology
Formula
Absolute reticulocyte count = % of reticulocytes x (actual hematocrit/ normal hematocrit) Reticulocyte index = absolute reticulocyte count / maturation factor Maturation factor: Hematocrit ≥ 35%: 1.0 35% > Hematocrit ≥ 25%: 1.5 25% > Hematocrit ≥ 20%: 2.0 20% > Hematocrit: 2.5
Measured Factor Low Impact
  • A reticulocyte index less than 2% indicates hypoproliferation to anemia.
Measured Factor High Impact
  • A reticulocyte index greater than 2% indicates adequate response to anemia.
Preparation
  • A blood test is used to determine % of reticulocytes and hematocrit.

Result Interpretation

Ranges Ranges
  • Critical Low: Absolute reticulocyte count: < 0.5% Reticulocyte index: < 2%
  • Critical High: Absolute reticulocyte count: >1.5% Reticulocyte index: > 3%
  • Normal: Absolute reticulocyte count: 0.5%-1.5% Reticulocyte index: > 2%
  • Normal Adult Male: Absolute reticulocyte count: 0.5%-1.5% Reticulocyte index: > 2%
  • Normal Adult Female: Absolute reticulocyte count: 0.5%-1.5% Reticulocyte index: > 2%
  • Normal Geriatric Male: Absolute reticulocyte count: 0.5%-1.5% Reticulocyte index: > 2%
  • Normal Geriatric Female: Absolute reticulocyte count: 0.5%-1.5% Reticulocyte index: > 2%
Result Low Conditions
  • Aplastic anemia
  • Megaloblastic anemia
  • Hypoproliferation to anemia
  • Iron deficiency anemia
  • Folic acid deficiency
  • Vitamin B-12 deficiency
Result High Conditions
  • Polycythemia vera
  • Heart disease
  • Leukemia
  • Lymphoid neoplasms
  • Metastasis
  • Sepsis
  • Malaria
  • Hyperproliferation to anemia
  • Hemolytic anemia
  • Blood loss
Test Limitations
The study by Kalahasthi demonstrated a positive and significant association between the smoking habit and reticulocyte count indices. However, smoking status is not taken into account in the calculation of Absolute reticulocyte count and Reticulocyte index
References: 2
Study Additional 1
A cross-sectional study looked at the effect of lead exposure on reticulocyte count indices in 391 male workers from lead battery manufacturing plants. Blood lead levels were measured using an Atomic absorption spectrophotometer. The reticulocyte count (%) was estimated by using the supravital staining method. The hematocrit was measured using an ABX Micros ES-60 hematology analyzer. Statistical method included spearmen correlation and linear multiple regression analysis, with significant regression coefficient β when p-value was less than 0.05. There was a significant and positive association between blood lead levels and reticulocyte count indices, with reticulocyte count (β = 0.212, P < 0.001), absolute reticulocyte count (β = 0.217, P < 0.001), reticulocyte index (β = 0.194, P < 0.001), and reticulocyte production index (β = 0.208, P < 0.001). The study concluded that lead exposure may cause an increase of reticulocyte count indices.
References: 2
Study Additional 2
This study evaluated the role of reticulocyte maturation fractions and bone marrow reticulocyte in anemia classification. A total of 243 patients with aplastic, nutritional, and infiltrative anemias and anemia due to excess destruction and blood loss had bone marrow examination for morphologic diagnosis and reticulocyte evaluation. The absolute reticulocyte count and reticulocyte maturation fractions showed significant difference among marrow infiltration, aplastic anemia, and hemolytic anemia. Aplastic patients had lowest absolute reticulocyte count and reticulocyte maturation fractions. The study concluded that automated reticulocyte count with maturation fractions may classify anemias.
References: 3
Study Additional 3
A cross-sectional descriptive study evaluated the role of absolute reticulocyte count in identifying the cause of pancytopenia. A total of 429 patients with pancytopenia were evaluated for peripheral blood picture, complete blood counts, reticulocyte count, serum ferritin, B12, folate and bone marrow aspirate. Absolute reticulocyte counts were less than 25 x 10^9/L for aplastic anaemia, from 25 x 10^9/L to 50 x 10^9/L for nutritional anaemia, and greater than 100 x 10^9/L in marrow infiltrative disorders, sepsis, and malaria. The study concluded that absolute reticulocyte count may differentiate various causes of pancytopenia and might be included in pancytopenia work-up in order to avoid unnecessary bone marrow aspirations.
References: 4

Authors

Robert S. Hillman, MD, MACP, is a professor of Medicine at the University of Washington. His other roles are the Chief of Hematology at the Harborview Hospital, Director of the Health Sciences Learning Resource Center, Chief of Medicine at Maine Medical Center, and Director of the MMC Cancer Center. His research focuses on iron and folate metabolism
https://www.mitemmc.org/speakers-bureau/robert-s-hillman-md-macp/

References

  1. Hillman RS. Characteristics of marrow production and reticulocyte maturation in normal man in response to anemia. J Clin Invest. 1969 Mar;48(3):443-53.
  2. Kalahasthi R, Barman T. Effect of Lead Exposure on the Status of Reticulocyte Count Indices among Workers from Lead Battery Manufacturing Plant. Toxicol Res. 2016 Oct;32(4):281-287. Epub 2016 Oct 30.
  3. Lin CK, Chiu CF, Kuo BI, Lin FM, Jiang ML, Chow MP. Do the reticulocyte maturation fractions and bone marrow reticulocyte count further help the classification of anemias? Zhonghua Yi Xue Za Zhi (Taipei). 1994 May;53(5):270-5.
  4. Priya P P, A R S. Role of absolute reticulocyte count in evaluation of pancytopenia-a hospital based study. J Clin Diagn Res. 2014 Aug;8(8):FC01-3.