Absolute Reticulocyte Count (ARC) Lab Values

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Included In This Lesson

Outline

Objective:

Determine the significance and clinical use of  Absolute Reticulocyte Count in clinical practice

 

Lab Test Name:

Absolute Reticulocyte Count

 

Description:

Measures the number of reticulocytes per microliter of blood

Reticulocytes (%) x RBC count (millions of cells/microL)

Requires:

Normally functioning bone marrow- 

  • adequate content of iron, folate, coalamin (vitamin B12), and copper

Proper kidney function-

  • Detection of reduced oxygen content
  • Erythropoietin (EPO) produced in response to stimulate bone marrow production of RBCs

 

Indications:

Anemia

  • Therapeutic effect of treatment
    • Determines cause of anemia
      • Deficiency 
        • iron, vitamin B12, folate
        • Rapid recovery expected, within one to two weeks of repletion
      • Malabsorption syndromes 
        • celiac disease, autoimmune gastritis, bariatric surgery
      • Hemolysis 
        • rapid drop in Hgb

Monitoring bone marrow function 

  • Post chemo
  • Post radiation

 

Normal Therapeutic Values:

Normal – a normal result for healthy adults who are not anemic

  • 0.5-2.5%

Collection:

  • CBC
  • Lavender tube

 

What would cause increased levels?

A higher than normal reticulocytes count may indicate:

  • Anemia due to red blood cells being destroyed earlier than normal (hemolytic anemia)
  • Bleeding
  • Blood disorder in a fetus or newborn (erythroblastosis fetalis)
  • Kidney disease, with increased production of a hormone called erythropoietin
  • Reticulocyte count may be higher during pregnancy

 

What would cause decreased levels?

A lower than normal reticulocyte count may indicate:

  • Bone marrow failure (for example, from a certain drug, tumor, radiation therapy, or infection)
  • Cirrhosis of the liver
  • Anemia that is caused by low iron levels, or low levels of vitamin B12 or folate
  • Chronic kidney disease
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Transcript

Hey everyone. Abby here with nursing.com. This lesson will cover the normal increased and decreased values for Absolute reticulocyte count or ARC. Let’s get started.

 

Absolute reticulocyte count is a lab that measures the number or percentage of reticulocytes in a blood sample. This is a peripheral blood smear showing a reticulocyte, which is an immature red blood cell. This lab is used to assess bone marrow function, because that’s where our blood components are produced. How this lab is calculated is the percentage of reticulocytes are multiplied by the number of red blood cells and that gives us our ARC. Now, bone marrow needs nutrients like iron and folate and vitamin B12, even copper to function normally. So, when we are assessing for bone marrow function, this lab helps us to see if the bone marrow is spitting out a whole bunch of reticulocytes trying to become red blood cells? Is it functioning properly, or is there a component missing? Also, we need to have proper kidney function in order to produce red blood cells.

 

The kidney produces erythropoietin, which is a hormone that tells the bone marrow, hey, we need erythrocytes or red blood cells. It detects a dip in oxygen content in the blood. Some clinical indications. What do you think? Do you think this would be someone that has low red blood cells? Uh, what would cause that, what do you think? If you were thinking anemia, you’re totally right. Patients with anemia have deficiencies that cause a dip in the production of red blood cells, or they’re the wrong size, or they keep hemolyzing. This actually helps us, this lab determines the cause of the anemia. It’s also indicated for patients that are receiving cytotoxic treatments, uh, whether that be chemotherapy or radiation. Normal therapeutic value is between 0.5 and 2.5% for healthy adults without anemia. It is collected in a CBC with differential, in a lavender tube, just like this one.

 

When this lab value is increased, when we have an increase of the absolute reticulocyte count, that can tell us about anemia like we talked about and more particularly, the cause whether it’s pernicious anemia, hemolytic anemia, et cetera, et cetera. Also, it will be increased if there’s bleeding or hemolysis. The body senses that red blood cells are missing and calls on the bone marrow to increase red blood cell production and what are red blood cells first?  Reticulocytes, very good. It can also be increased in fetuses or a newborn with a blood disorder. It does also rise in kidney disease, because in kidney disease, it over produces erythropoietin like we talked about on our first slide. Now, it can also be normal for the absolute reticulocyte  count to be elevated during pregnancy. The inverse is when this lab is low. So, when there are fewer reticulocytes in circulation, that indicates bone marrow failure. It can also be in the case of cirrhosis, and like we talked about, deficiencies. And then chronic kidney disease, that poor kidney just trying its hardest to produce the erythropoietin. That brings us to our linchpins. 

 

The absolute reticulocyte count is the percentage of red blood cells that are reticulocytes or immature red blood cells. The normal value for healthy adults that are not anemic is between 0.5 and 2.5%. This value will increase in cases of blood loss or lysis, particularly hemolytic anemia and kidney disease. The value will be decreased if bone marrow function is suffering or there are nutrient deficiencies. You all did so great on this lesson. We know you can do this and we love you guys, now go out and be your best self today and as always, happy nursing!

References:

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