Absolute Reticulocyte Count
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Reticulocytes
unit % Fraction
RBC Count ( x 10^12/L)
R e s u l t s
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ARC
 
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Absolute Reticulocyte Count

Reticulocytes are young, immature, nonnucleated red blood cells (RBC) that contain cytoplasmic reticular material (mRNA) and are larger than mature RBCs. Reticulocytes are released into the circulation 1-2 days before reaching full maturity. As the reticulocyte matures during the first 24-48 hour after being released into the peripheral blood, it loses its remaining ribonucleic acid (RNA). The absolute reticulocyte count (ARC) relates to the reticulocyte count (as a % of total RBCs that are reticulocytes) multiplied by the total number of RBCs.

The ARC is a significant index of erythropoietic activity in the bone marrow and assists in the differential diagnosis of anemia.

To calculate ARC, multiply the percentage reticulocytes by the RBC count in units of cells/µL.

ARC (cells/mm 3 ) = Reticulocyte fraction * RBCs (cells/mm 3 )

In cases of anemia, the ARC helps to differentiate between hypoproliferative and hyperproliferative causes. An ARC of 25,000-85,000 cells/mm 3 is normal (in non anemic patients).

ARC>=100,000/mm 3 : Hyperproliferative Anemia

  • Acute blood loss
  • Hemolytic anemia
    • Hemoglobinopathies and sickle cell disease
    • Immune hemolytic anemia
    • Malaria
    • Primary RBC membrane defects
    • RBC enzyme deficits
  • Infiltrative marrow disorders
  • Response to specific therapy as in:
    • Drug-induced anemia
    • Iron-deficiency anemia
    • Megaloblastic anemia (Vitamin B 12 , Folic Acid)
    • Pernicious anemia
  • Drugs
    • Acetanilide
    • Acetylsalicylic acid
    • Amyl nitrate
    • Antimalarials
    • Antipyretics
    • Antipyrine
    • Arsenicals
    • Corticotropin
    • Dimercaprol
    • Furaltadone
    • Furazolidone
    • Levodopa
    • Methyldopa
    • Nitrofurans
    • Penicillin
    • Procainamide
    • Sulfones

ARC<100,000 mm 3 : Hypoproliferative Anemia

  • Alcoholism
  • Anemia of chronic disease
  • Aplastic anemia
  • Disorders of RBC maturation
    • Anemia of chronic disease
    • Iron deficiency anemia
    • Sideroblastic anemias
    • Vitamin deficiency anemia
  • Endocrine problems
  • Infections
  • Myelodysplastic syndromes
  • Pernicious anemia
  • Radiation therapy
  • Renal disease (decreased erythropoetin)
  • Tumor in marrow (bone marrow failure)
  • Drugs and toxins
    • Azathioprine
    • Chemotherapeutic agents (many)
    • Chloramphenicol
    • Dactinomycin
    • Hydroxyurea
    • Methotrexate
    • Zidovudine

References :

Reticulocyte Count. Labs 360. ePublication, Skyscape, Inc.